chapter 5 technologies for assessing human reproductive

Chapter 5

Technologies for AssessingHuman Reproductive Function

CONTENTSPage

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......129

Tests of Male Reproductive Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......,131The Fertility Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . .+....... . ..,.......,131Semen Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...135Sperm Function . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........................138

Tests of Female Reproductive Health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ....140Personal History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..., . ......141Physical Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......141Ovarian Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~Cervical Mucus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Endometrial Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Tubal Patency/Uterine Structure . . . . . . . . . . . . . . . . . . . . . . . .Implantation/Establishment of Pregnancy . . . . . . . . . . . . . . . .Embryonic Differentiation and Fetal Development . . . . . . . . .Delivery and Lactation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Technical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 5 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

List of TablesTable No.5-l. Patient History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2. Circumstances for Which Amniocentesis is Recommended5-3. Use of Ultrasound in Fetal Monitoring . . . . . . . . . . . . . . . . .

List ofFi@resFigure No.

5-1. Chronology of Fertility Evaluation. . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . 141

. . . . . . . . . . . . . . . 145

. . . . . . . . . . . . . . . 145

. . . . . . . . . . . . . . . 146

. . . . . . . . . . . . . . . 146

. . . . . . . . . . . . . . . 146

. . . . . .,,.,. . . . . 150

. . . . . . . . . . . . . . . 151

. . . . . . . . . . . . . . 152

. . . . . . . . . . . . . . 155

Page. . . . . . . . . . . . . . . 132. . . . . . . . . . . . . . . 148. . . . . . . . . . . . . . . 150

. . . .Page

. . . . . . . . . . . 1305-2.Diagnostic Techniques in Fertility Assessment . . . . . . . . . . . . . . . . . . . . . . . ,1335-3. A Gauge Used to Measure the Occurrence of Erection During5-4.5-5.5-6.5-7.5-8.5-9.

5-1o.5-11.5-12.5-13.

Sperm Agglutination . . . . . . . . . . . . . . . . . . . . .Sperm Movement Patterns. . . . . . . . . . . . . . . .Sperm Morphology: Some Categories . . . . . . .The Morphology Overlay . . . . . . . . . . . . . . . . .The Menstrual Cycle . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

Sleep . . . . .135. . . . . . . . . . . 136. . . . . . . . . . . 137. . . . . . . . . . . 138. . . . . . . . . . . 139. . . . . . . . . . . 143

Basal Body Temperature Patterns Throughout the Menstrual Cycle .. ....144Cervical Mucus Ferning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ~.. ... ... ..l45Mean Human Chorionic Gonadotropin (hCG) During Pregnancy. . ........147Amniotic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ...147Chorionic Villus Biopsy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., ...149

Chapter 5

Technologies for AssessingHuman Reproductive Function

INTRODUCTION

One of the clearest indicators of reproductivehealth in a population is the incidence of healthyoffspring. Birth statistics can be misleading, how-ever, in their failure to indicate the number ofcouples who are not engaging in procreation orare unable to reproduce. Although individualswho wish to have children often take for grantedtheir physical ability to do so, exposure to cer-tain chemical, physical, or biological agents cancompromise reproductive health and sexual func-tioning (chapter 4 describes the effects of indi-vidual agents).

Because of the structural and functional differ-ences between the sexes, exposure to one of theseagents may impair the reproductive capacity ofone sex and not the other. Individual character-istics and lifestyle differences (e.g., smoking, age,nutrition) also alter sensitivity to some agents.Monitoring the reproductive health of individualsexposed to known or suspected reproductive haz-ards is thus an important step.

The following section describes the diagnosticprocedures available to patients experiencing re-productive health problems. Although the em-phasis is on infertility, it must be stressed thata thorough assessment of reproductive healthincludes factors not directly related to conception and fetal development (e.g., pubertal de-velopment, libido). Reproductive health refersto the entire composite of human reproductiveand sexual functions and their integration withother organ systems (see chapter 3).

It is critical to note that an individual’s repro-ductive competence cannot be verified in isola-tion. Fertility is the product of the specific inter-action of a couple. Physical examination andlaboratory analyses may determine that a manor woman is potentially fertile (i.e., sound repro-ductive organs, normal hormone levels, presenceof reproductive cells), but fertility is verified only

after the couple has given birth to a healthy in-fant. Evaluation and treatment of infertility musttherefore consider the couple as a unit. Ideal man-agement is best achieved when the couple is seentogether by a team of physicians (e.g., the manby a urologist, the woman by a gynecologist) (61).

Three features form the basis of a fertility evalu-ation in both men and women:

1. personal history (including medical, familial,occupational, and reproductive background);

2. physical examination; and3. laboratory analyses (e.g., hormone studies,

semen analysis, cervical mucus assays) (seefigure 5-l).

Biological and practical considerations, however,demand that the parameters measured and themethods used be quite different for the two sexes.Whereas the male reproductive organs and germcells (sperm) are readily accessible, the femalecorrelates are not.

Physical examination of the male is simplifiedby the fact that his reproductive organs are ex-ternal. Moreover, laboratory analysis of semenis a routine component of the male fertility evalu-ation. A man’s ability to produce a semen sam-ple and the analysis of various physical and func-tional properties of the sample provide animportant indication of his reproductive health.These assays are safe, rapid, and easily performedwith equipment standard to most hospitals andfertility clinics,

Unlike the male, the female reproductive organsare internal and her germ cells (eggs) do not leaveher body. Direct observation of a woman’s repro-ductive organs and germ cells, therefore, requiresan invasive procedure or the use of special imag-ing equipment. The assessment of female repro-ductive competence thus relies heavily on indirectindicators. [An indirect indicator is defined here

129

— —

130 . Reproductive Health Hazards in the Workplace

Figure 5=1.—Chronology of Fertility Evaluation

Key:

?

= Female procedure

f l= Male procedure

?

SOURCE: Adapted from M. M, Seibel, “Infertility,” in Gyneco/ogic Decision Making, Emanuel A, Friedman (cd.) (Philadelphia: B. C. Decker Inc., 1983), pp. 68-69.

Ch. 5—Technologies for Assessing Human Reproductive Function ● 131

as one in which the reproductive endpoint un-der study is not observed, but its function is as-sumed based on the occurrence of related events.For example, while ovulation—the release of anegg cell from the female ovary—is not readily ob-servable, there are associated changes in hormonelevels and in body temperature that indicate whenovulation has occurred,] (A discussion of male andfemale reproductive function appears in chapter3.)

Fertilization is but one of several events thatare critical to successful reproduction. Others in-clude transport of the fertilized egg to the uterus,implantation in the uterine wall, growth and de-velopment of the embroyo/fetus, and delivery. Be-.cause each of the events subsequent to fertiliza-tion occurs within the female, the ability toaccommodate and maintain a pregnancy is a com-ponent of female reproductive function.

As with other aspects of fertility, there is noabsolute verification that can be made of a wom-an’s ability to conceive and sustain a pregnancy,short of her actually doing so. However, several

clinical techniques enable the physician to moni-tor these events as they occur. These may proveuseful in isolating the effects of various agentson the reproductive health of exposed individualsor on their offspring. In-utero monitoring of em-bryo/fetal development, for example, may detectthe effects of agents that do not impede concep-tion, but that elicit structural or functional ab-normalities in the offspring of those exposed.

The following discussion examines methods forassessing human reproductive health, includingevents preceding, following, and independent offertilization. These are the diagnostic techniquesused with patients experiencing reproductivehealth problems. While diagnosis of the physio-logical basis of a reproductive disorder does notnecessarily identify its source (e.g., workplace ex-posure, lifestyle characteristic), tracing patternsin the incidence of reproductive problems (e.g.,infertility, deformed offspring) may make thesecorrelations possible. The use of epidemiology andanimal toxicology studies to identify reproductivehazards is discussed in chapter 6.

TESTS OF MALE REPRODUCTIVE HEALTH

The Fertility Evaluation

Personal His tory

Obtaining a thorough personal history is thefirst and one of the most important steps in a fer-tility evaluation. Information about the individ-ual’s personal and familial health background andthe couple’s sexual interaction can provide impor-tant insights into the cause of infertility. Certaindrugs, medical procedures, and diseases, for ex-ample, can compromise reproductive function.Coital method (e.g., use of certain vaginal lubri-cants, timing, position) can also contribute to fer-tility problems, as can certain personal practices(e.g., frequent exposure to excessive heat as fromsaunas and hot baths). It is also important for thephysician to ascertain whether the patient has ex-perienced any form of sexual dysfunction (e.g.,impotence or decreased libido), whether the cou-ple engages in intercourse during the woman’sovulatory period, at which time she is most likely

to conceive, and whether the male has success-fully fathered healthy children with his presentor any previous mate. Table 5-1 outlines the com-ponents of a thorough personal history question-naire. In addition, a sample personal history ques-tionnaire is shown in appendix A.

Phys ica l Examinat ion

A careful physical examination is critical to thefertility evaluation. This includes examination ofthe secondary sex characteristics (e.g., hair dis-tribution, breast development), and of cardiovas-cular and necrologic function (e.g., strength ofpulse in lower extremities, reflexes, pelvic sen-sation), as well as of the genitals. The presenceand structural adequacy of the various compo-nents of the genital tract (e.g., vas deferens, pros-tate, epididymides) must be verified. Particularstructural abnormalities associated with impairedfertility are sought (e.g., hernia, varicocele–

—


Table 5-1 .—Patient History

Sexual historyDuration of sexual relations with and without birth control.

Methods of birth control.Sexual technique: penetration, ejaculation, use of lubricants

(some are spermicidal).Frequency and timing of coitus. Does it coincide with ovu-

lation?Past marital history of both partners, including pregnancies

and miscarriages.

Past history: ma/eDevelopmental: age of testicular descent, age of puberty, his-

tory of prepubertal obesity, gynecomastia (excessivebreast development), congenital abnormalities of urinarytract or central nervous system.

Surgical: orchiopexy (surgical placement in the scrotum ofan undescended testis), pelvic or retroperitoneal (behindthe abdomen) surgery, herniorrhaphy (surgical repair ofa hernia), sympathectomy (interruption of sympathetic ner-vous system pathways), vasectomy, injury to genitals, spi-nal cord injury.

Medical: urinary infections, venereal disease (including non-specific urethritis), mumps, renal disease, diabetes, radi-otherapy, recent allergic febrile (fever-inducing) or viralillness (may affect semen quality), epididymis, tubercu-losis, smallpox (causes obstructive azoospermia) or otherchronic diseases, anosmia (absence of sense of smell),midline defects.

Drugs: complete list of all past and present medications.Many drugs may interfere with spermatogenesis, erection,ejaculation.

Occupation and habits: exposure to chemicals and heat, hotbaths, steam baths, radiation, biological agents, physicalexertion, cigarettes, alcohol, diet, other habits.

Sexual: libido, erectile capacity, ejaculatory capacity, posi-tion during coitus.

Past marital history of both partners: any offspring with otherpartners.

Previous infertility evaluations and treatments.

Past history: femaleDevelopmental: age at onset of menstruation, age at develop-

ment of secondary sex characteristics (e.g., breast devel-opment), congenital abnormalities of central nervoussystem.

Surgical: pelvic operations, appendectomy,Medical: tuberculosis, venereal disease, endometriosis (aber-

rant appearance of uterine-like tissue in various locationsin the pelvic region), tumors, menstrual irregularities, di-abetes, other chronic diseases.

Menstrual: regularity of menstruation, length of menstrualcycle, number of days of menstrual bleed per cycle, pre-menstrual symptoms (e.g., pain, water retention).

Contraception: present and past methods.Obstetrics: full-term deliveries, pregnancy complications,

abortions, premature deliveries, previous infertility.Drugs: complete list of all past and present medications.Occupation and habits: exposure to chemicals, radiation, bi-

ological agents, physical exertion, cigarettes, alcohol, diet,other habits.

Sexual: libido, orgasm capacity, position during and aftercoitus.

Family historyBlood diseaseCancerCongenital defectsEndocrine disorderGenetic diseaseHeart conditionImpaired offspringKidney diseaseNecrologic disorderReproductive disorder

SOURCE: Adapted from: R. J. Sherins and S. S. Howards, “Male Infertility,” Campbell’s Urology, J. Hartwell Harrison, Reuben F. Gittes, Alan D. Perlmutter, ThomasA. Stanley. and Patrick C Walsh (eds.) (Philadelphia: W. B. Saunders Co., 1978), pp. 715-776; and J R Wilson, “infertility,” Obstetrics and Gynecology William-.J. Ledger (cd.) (St. Louis, MO: C. V. Mosby Co., 1983), pp. 160.174.

varicose veins in the testes, hypospadias-openingof the penis on the underside.) In addition, thesize and volume of the testes are measured, astesticular atrophy is an indication of reducedsperm supply (3,22,59). (See figure 5-2.)

Physical examination of a patient who describesproblems with impotence may include an assess-ment of erectile capacity. Determining the occur-rence of erections during sleep (nocturnal peniletumescence—NPT) is considered one of the bestmeans for distinguishing between physiologic andpsychogenic causes of sexual dysfunction (64).NPT monitoring may be done in a laboratory orat home. The principle of the monitoring deviceis the same in either case: a strain gauge wornaround the penis indicates changes in penile cir-

cumference during sleep. * (See figure 5-3.) Whilemonitoring devices used at home are less preciseand cannot measure certain other relevant fac-tors (e.g., duration of erection, correlation withREM sleep cycles), some physicians find that theyprovide a sufficient indication of nocturnal erec -tile function for most patients. The cost of thehome monitoring device is significantly lowerthan that of laboratory monitoring (i.e., $15 asopposed to $1,500) (64).

● One simple home monitoring method uses postage stamps tomeasure NPT. Torn perforations in a ring of stamps worn duringsleep indicate nocturnal erection.

—

Ch. 5—Techno/ogies for Assessing Human Reproductive Function ● 133

Figure 502.- Diagnostic Techniques in Fertility Assessment

Parameter Test

134 “ Reproductive Health Hazards in the Workplace

Test

t 1

Body temperature:Woman’s body temperature

‘ “- taken on waking every day.A rise in temperature mayindicate ovulation,

Hormone assays: Normalovarian activity isreflected by timed shiftsin blood/urine hormoneconcentrations throughoutthe menstrual cycle.

Endometrial biopsy:Tissue scraped from liningof uterus can reveal the—influence of ovarianhormones, ver i fy ing

—

tubal obstruction oruterine irregularity.

,Laparoscopy: Fiberoptic

: . 4 scope, inserted into

H y s t e r o s a t p i n gogram:

X-ray traces iodine dye

S 1

through cervix and fallopiantubes to uterus to detect 1

lrllecIlon or enaometrtosis,an ahnnrmcal m.,-.,., +h A4 L

‘1 reproductive organs onvideo screen. I

t

SOURScience.


Figure 5-3.—A Gauge Used to Measure the Occurrenceof Erection During Sleep

Diameter of gauge is approximately 1.5 inches

SOURCE Medica/ World News 25:47-52, 19&

Laboratory Evaluation

Examination of the male experiencing reproduc-tive difficulties may include one or more of thefollowing laboratory procedures:

●

●

●

Semen analysis Evaluation of semen is oneof the cornerstones of the infertility exami-nation. A variety of procedures can be usedto assess the structural and functional char-acteristics of the patient’s sperm and semi-nal fluid.Hormone assay. Where semen analysis re-peatedly shows abnormalities, hormone as-says may inform the physician about thesource of the difficulties. (See Tech. Note 1.)The proper balance of hormones in the bloodis critical to the entire range of reproductivefunctions.Urinalysis and urine culture. These screenfor urinary tract infections or disorders thatmight hamper reproductive function.

Because of the prominence of semen analysisin examination of the male fertility patient, thefollowing discussion examines the components ofa standard semen analysis and their relevance toreproductive and sexual function.

Semen Quality

Several physical characteristics of semen havebeen associated with male reproductive compe-tence. These include:

● ejaculate appearance,. ejaculate pH,● ejaculate volume,● sperm density,● sperm motility,. sperm vitality, and● sperm morphology.

Researchers in the field disagree as to whichof these endpoints most significantly effects makfertility, There is presently no definitive indication that any single factor is the most importantRather, it appears that they operate together indetermining the reproductive competence of eachindividual (15,18,19).

In addition, there is no broadly accepted defi-nition of what constitutes “normal semen. ” Lab-oratories differ in what they designate as the crit-ical level for each semen characteristic (e.g., thenumber of motile or morphologically normaIsperm, the rate of forward progression). Severalfactors contribute to these disparities:

●

●

●

●

The quality and quantity of semen vary sig-nificantly among all men, even among fertilemen.Each individual is subject to normal fluctua-tions in semen quality and quantity. Age, sea-sonal change, illness, and ejaculation fre-quency are among the factors known t o

induce these shifts. *Many of the measurements included in a se-men analysis are subjective, qualitative judg-ments. This makes comparison of data fromdifferent laboratories and/or different clini-cians difficult.Proper collection and diagnostic techniquesare critical. Accuracy of findings may be com-promised if the specimen is collected incor-rectly, not analyzed promptly, or mishandledin any way.

“Because of (he fluctuations in semen c~ualit~r and the potential

for laboratory error, a minimum of three semen samples is usuall)rrfxxmmx+nfled. An interxal of at least 10 dajs t)etwfxm samples, withsexual atx+tinfmcf’ for 2 to 4 da)’s prfwxding sample collf’rtiorl, isoptimal (61 ).

136 ● Reproductive Health Hazards in the Workplace

● The methods and standards for statisticalanalysis of semen quality data vary, makingcomparison of results from different studiesdifficult.

Although efforts are being made to develop meth-ods that will standardize and objectively measurethese parameters, the time, expense, and amountof equipment they require are as yet beyond themeans of many laboratories and clinics. Thus,while semen analysis remains an important aspectof a fertility examination, there are no absolutevalues associated with any of the physical char-acteristics that are assessed.

Ejaculate Appearance

Several physical properties of healthy semenmake evaluation of ejaculate appearance an im-portant step in the assessment of semen quality:

●

●

●

Freshly ejaculated semen is a white, yellow,or gray fluid that coagulates at the time ofejaculation.Enzymes produced by the prostate glandcause the semen to liquify 3 to 25 minuteslater. Semen viscosity is, therefore, a meas-ure of secretory activity and enzymatic func-tion of the prostate and seminal vesicles (61).A high incidence of agglutination (head-to-head, head-to-tail, or tail-to-tail clumping)among the spermatozoa in a sample may in-dicate the presence of infection or of anti-sperm antibodies in the seminal fluid. (SeeTech. Note 2.) An observation of greater than10 percent agglutination in a sample is con-sidered abnormal (19,23). (See figure 5-4.)

Ejaculate pH

Normal semen pH is 7 to 8. A low pH may bethe result of a contaminated sample or may indi-cate obstruction of the ejaculatory ducts (61).

Ejaculate Volume

The amount of semen in an ejaculate normallyranges from 2.5 to 5 milliliters (19).

● Smaller volumes may indicate functional defi-ciencies of the prostate and/or seminal vesi-cles, or incomplete collection (19,23).

Figure 5-4.—Sperm Agglutination

Sperm clumping head to head (agglutination)

● Excessive ejaculate volumes may be the re-sult of a long period of abstinence prior tothe test procedure.

Where abnormal ejaculate volumes are obtained,the test should be repeated to differentiate faultycollection technique from physiological impairment.

Sperm Dens i ty

Sperm density refers to the number of spermper milliliter of semen. Microscopic observationenables these counts to be made. Automated tech-niques are also available (7 I).

Despite the relative ease and objectivity withwhich sperm density can be measured, there re-mains no uniformly accepted specification of thenumber of sperm per milliliter of semen neces-sary to establish fertility (23,71). (See Tech. Note3.) Two factors contribute to this uncertainty:

1. Total semen volume and number of spermper ejaculate differ among all men, evenamong fertile men. There is no sperm con-

Ch. 5—Technologies for Assessing Human Reproductive Function . 137

centration threshold-except zero—belowwhich a man is absolutely infertile.

2. Each male is subject to natural fluctuationsin sperm concentration (71). Age, seasonalchange, illness, and ejaculation frequency areamong the factors known to induce shifts inthis parameter (23).

Because of sperm density variability, at leastthree semen samples must be analyzed beforeconcluding that a man is azoospermic, * oligosper-mic, * * or normal (61). Where few or no spermare ejaculated and normal hormone levels havebeen confirmed, the physician must determinewhether the absence of sperm is due to impairedsperm production or to obstruction of the ejacu-latory ducts. Testicular biopsy (extraction andmicroscopic observation of testicular tissue) andlasography (X-ray of the seminal transport sys-tem) are the two diagnostic procedures used forthese purposes (59). (See Tech. Note 4.)

Sperm Motility

The importance of sperm motility in establish-ing male fertility is well documented (15)18,23,33,50,70). There is a strong correlation betweenmotile sperm and successful fertilization (7,46).No precise data on the levels of motility neces-sary to establish fertility are available, however,because this parameter is difficult to measure ac-curately and objectively (23,71).

Several factors contribute to the difficulties indefining specific levels of sperm motility neces-sary to establish fertility:

● The sensitivity of sperm motility to temper-ature and to time between collection andmeasurement limits the comparability of datafrom different laboratories, where collectionprocedures may vary (71),

The extreme subjectivity of the visual ratingsystem commonly used in motility assessmentmakes comparison of motility data fromdifferent laboratories problematic. (See Tech.Note 5.)

● Azoospermia is the complete ahsence of sperm.* ‘oligospermia refers to extremel~ Imt’ lelels of spf?rm prO-

(lLJ(Y ion

Despite these difficulties, recognition of the sig-nificance of sperm motility in relation to fertilityhas inspired efforts to develop precise, objectivemeasures of this parameter (23). These encom-pass a range of photographic and automated tech-niques through which overall sample motility andindividual sperm velocities may be determined.(See Tech. Notes 6-8 and figure s-5.)

While each of these techniques offers increasedobjectivity and accuracy in the measurement ofsperm motility, the equipment, time, and expensethey require limit their clinical applicability (50),and standard clinical tests of sperm motility re-main of limited predictive value with regard tofertility (71).

Figure 5.5.—Sperm Movement Patterns

A) Immotile spermatozoon; B) stationary spermatozoon with activeflagellum; C) roiling spermatozoon; D) yawing spermatozoon; E)straight-swimming spermatozoon exhibiting neither rolling noryawing.

SOURCE: J. W. Overstreet, D, F, Katz, F. W. Hanson, et al., “A Simple inexpen-sive Method for Objective Assessment of Human Sperm MovementCharacteristics,” Ferti/ity & Sterility 31:162-172, 1979. Reproduced withpermission of the publisher, The American Fertility Society.


Sperm Vitality

A dye that selectively stains dead cells permitsthe ratio of live to dead spermatozoa in a sampleto be determined. This technique is particularlyuseful in semen samples showing low levels ofmotility because it enables differentiation betweenimmotile and dead sperm (19,23).

Sperm Morphology

The natural diversity of sperm shape and sizeamong both fertile and infertile men makes it dif-ficult to define “normal sperm morphology.”while the prototypical human sperm is char-acterized as having an oval head, estimates of itsdimensions and of the percentage of sperm thatmust be of this ideal morphology in order toachieve fertility are disputed by fertility experts.

The subtlety of the structural variations amongsperm further complicates efforts to categorizethe cells. Judgments are qualitative and subjec-tive, limiting comparisons of morphology datafrom different laboratories, and making it diffi-cult to determine the precise relationship ofsperm morphology to fertility (15,18,23).

Recent efforts to standardize these measure-ments include the use of:

●

●

●

reference slides (70);morphology overlays (36); anddirect morphometric measurement (i.e.,length, width, area, circumference) (35,58).(See Tech. Note 9 and figures 5-6 and 5-7.)

However, no morphology assessment techniquecompletely eliminates the role of human decisionand human error in evaluating this parameter.It remains difficult to define specific criteria forthe shape, size, and percentage of “normal” spermnecessary to establish male fertility.

Despite these difficulties, there is substantial evi-dence for the importance of sperm morphologyin establishing male reproductive capacity (36,70), * Although subjective, evaluation of spermmorphology remains an important component ofsemen analysis.

Sperm Function

Sperm Funct ion

Because tests of semen quality have failed toprovide specific, reliable criteria by which to as-sess male reproductive capacity, researchers are

● Studies show that morphologically abnormal sperm are poorlyor nonmotile, making these misshapen cells less viable (17,36,43,52).

Figure 5-6.-Sperm Morphology: Some Categories

Abnormal Cytoplasmic Shapeless Large Small Tapered Double Immature Coiled Double

Normal midpiece droplets head head head head head form tail tail

SOURCE: Reprintad from You Can Have a Baby. Illustrations by Delia Malone. Copyright @ 1985 by Joseph H. Bellina, M. D., and Josleen Wilson. Used by permissionof Crown Publishers, Inc.

Ch. 5—Techno/ogies for Assessing Human Reproductive Function . 139

Figure 5.7.—The Morphology Overlay

OVALLength 3-5~mWidth 2-3Pm

MEGALOCEPHALICLength >5PmWidth >3Pm

MICROCEPHALIC TAPERING TAPERING AMORPHOUSLength <3Pm Length >5Pm Length 3-5Pm Length 3-5PmWidth <2pm Width <3pm Width <2Pm Width >3~m

Base of sperm is aligned with the bottom of the overlay. If the length and width lie between the two boxes, the classification is oval or “normal”morphology.

SOURCE: D. G. Katz. L. Diel, and J. W. Overstreet, ‘rDifferences in the Movement of Mor~holoaicallv Normal and Abnormal Human Seminal Spermatozoa,” Bio/oov- . -.of Reproduction 26:566-570, 1982.

seeking alternative methods. These emphasize thefunctional ability rather than the physical char-acteristics of the sperm ceIls (1,23). While the ul-timate evidence of normal sperm function is con-ception, the following section describes two teststhat may be of predictive value.

Cervical Mucus Penetration

In order to reach and fertilize an egg cell, asperm must migrate from the vagina through thefemale endocervical canal (the pathway from thevagina to the uterus). Its ability to penetrate thecervical mucus that fills this area is an importantdeterminant in its successfully accessing the egg.

There are several laboratory techniques for theevaluation of sperm-cervical mucus interaction.(See Tech. Note 10.) Each examines the ability ofthe sperm to penetrate the mucus and the vitalityof the sperm after penetration (i.e., some spermmay penetrate but thereafter become immobi-lized) (12,38,39,65),

A significant caveatof cervical mucus:

● Normal changes

of the test is the variability

in mucus quality occurthroughout the menstrual cycle (23). As a re-sult, a woman’s mucus may resist her hus-band’s sperm in one test, and be easily pene-trated in a subsequent study (5).

● The mucus of different women, even womenat the same stage of their cycle, varies in its

receptivity to sperm, making it difficult toestablish specific, broadly applicable criteriafor mucus penetration in relation to fertility(19)23).

In order to account for these differences, it isuseful to do a cross-study of both the semen andthe cervical mucus with control samples. (SeeTech. Note 11.) This enables the physician to de-termine whether the couple’s fertility problem isattributable to one of the two partners or is theresult of a compatibility problem.

Where a compatibility problem is suspected, itmay be useful to check for the presence of anti-sperm antibodies. Antibodies can occur in themale—autoimmunity --or in the female—sperm al-lergy. They may be present in the blood serumand/or the reproductive tract of either individ-ual and can cause varying degrees of reproduc-tive impairment, from reduced fertility to infer-tility. Various techniques enable the detection ofantisperm antibodies in the blood, semen, andcervical mucus. The latter presents the most dif-ficulty, making confirmation of antisperm anti-bodies in the female reproductive tract problem-atic (9). (See Tech. Note 12.)

Sperm-Oocyte In terac t ion

For fertilization to occur, a single sperm cellmust succeed in penetrating a female egg cell.Ethical considerations bar laboratory experimen-


tation with human sperm penetration of live hu- living human egg~ This technique is notman eggs (1). Two alternative techniques have yet widely available because of logistical dif-been developed: ficulties in obtaining a supply of human eggs. *

1$

2.

The more common of the two techniques— Difficulty in interpreting sperm-egg interactionthe zona-free hamster egg penetration tests persists because the percentage of spermtest—monitors the interaction of human that successfully penetrate a test egg varies sig-sperm with hamster eggs (72). Its reliability nificantly, even among fertile men. There is noas a definitive measure of male fertility, how- universally accepted definition of what constitutesever, remains uncertain. (See Tech. Note 13.) “normal sperm penetration.” (See Tech. Note 13.)Recognizing the weaknesses of the hamsteregg test, an alternative approach observes *The eggs are obtained from the ovaries of women undergoingthe interaction of human sperm with non- elective surgery (8,20,49).

TESTS OF FEMALE REPRODUCTIVE HEALTH

Because of the relative inaccessibility of the fe-male reproductive organs and their contents,assessment of female reproductive function re-lies heavily on inferential and indirect observa-tions. An indirect indicator is defined here as onein which the reproductive endpoint under studyis not observed, but its function is implied by theoccurrence of related events. Menstrual regular-ity is an example. It signifies the presence ofoocytes (egg cells) and the ability of the hypo-thalamic-pituitary -gonadal axis (the hormonalfeedback system) to coordinate ovulation (the re-lease of an egg cell from the ovary to the uterus),while none of these events is actually observed.(A discussion of female reproductive function ap-pears in chapter 3.)

This section describes direct and indirect meas-ures of the parameters that are assessed in a fe-male fertility evaluation. These include:

● Personal history Obtaining comprehensiveinformation about a patient’s medical,familial, occupational, and reproductive his-tory is the first step in a fertility evaluation.

● Secondary sex characteristics: The attain-ment of pubertal milestones and normal de-velopment of secondary sex characteristics(e.g., breast development, hair distribution)are an indication of hormone secretion andresponse.

● Ovarian function: The female ovary be-comes functional at the time of reproductive

●

●

●

maturity. Events that are associated with themonthly menstrual cycle denote ovarian ac-tivity and are important indications of femalereproductive health.Cervical mucus: Secretion of cervical mu-cus is fundamental to the female reproduc-tive cycle. The receptivity of a woman’s mu-cus to sperm is an important determinant ofher ability to become pregnant.Endometrial cells: Accommodation of preg-nancy necessitates thickening of the uterinewall. The appropriate growth response of thecells lining the uterus (endometrial cells) tomonthly hormonal secretions is an importantdeterminant of fertility.Tubal patency/uterine structure The struc-tural health of the fallopian tubes and uterusis necessary for the establishment of preg-nancy as a fertilized egg must travel throughthe tubes before implanting in the uterinewall. While no methods currently enablemonitoring of gamete transport, fertilization,zygote transport, or implantation, verifyingthe structural health of the fallopian tubesand uterus indicates the potential for theseevents to occur.

Assessment of these factors provides an indi-cation of a woman’s capacity to conceive. How-ever, because the events that succeed fertiliza-tion in the reproductive process occur within thefemale, there are additional aspects of female re-


productive competence that must be considered.These include:

● Implantation/establishment of pregnancy.Pregnancy is established when a fertilizedegg implants in the uterine wall. While nei-ther fertilization nor implantation are observ-able events, hormonal secretions provide anindication of their occurrence.

● Embryonic diffenntiation and fetal devel-opment The ability of the female reproduc-tive system to sustain a pregnancy and thenormal development of the fetus in utero canbe assessed through a variety of techniques.

● Delivery and lactation These are signifi-cant aspects of female reproductive functionthat may be assessed to determine effects oftoxic exposure.

Personal History

Obtaining information about a woman’s medi-cal, occupational, familial, and reproductive his-tory is the critical first step in a fertility evalua-tion. Information obtained in this initial stage ofthe examination can provide important insightsinto the source of fertility problems. A history ofmenstrual irregularity, pelvic inflammatory dis-ease, or surgery, for example, indicates a possi-ble physiological or anatomical basis for infertil-ity, while questions about coital frequency andtechnique may indicate that these are the sourceof the couple’s inability to reproduce.

Table 5-1 lists aspects of medical, occupational,personal, and familial history that are importantto a fertility assessment. The table reflects the im-portance of considering the infertile couple as aunit. A more detailed description of pertinent in-formation to be obtained from the infertile cou-ple is provided by the sample history question-naire in appendix A.

Physical Examination

Physical examination of the fertility patientseeks evidence of physiological and/or anatomi-cal bases for infertility. Standard health parame-ters (e.g., height, weight, blood pressure) andnecrologic function (e.g., reflexes, pelvic sensa-tion) are measured, and particular attention ispaid to any anatomical abnormalities.

While the gonads are not external in the femaleas they are in the male, secondary sex character-istics (i.e., breast development, hair and fat dis-tribution) are observable and provide an importantindication of hormonal secretion and response.Excessive facial and/or body hair, for instance,may be the result of androgenization (an excessof male hormones in a female).

A standard pelvic examination, including inspec-tion and palpation of structures throughout thegenital tract, may isolate infection, tumors, adhe-sions, or other abnormalities contributing to re-productive difficulties.

If this initial examination fails to isolate thesource of infertility, the physician undertakes amore detailed evaluation of the patient’s repro-ductive capacity. The foIlowing section describesthe specific parameters measured and the meth-ods used. (For a summary of the diagnostic tech-niques used, see figure 5-2.)

Ovarian Function

Although the female genital tract and the pri-mordial germ cells (the cells that develop into eggcells) are developed prenatally, ovarian activityfirst becomes apparent with the onset of menstru-ation at puberty. Consequently, damage sustainedas a result of prenatal toxic insult may go unno-ticed for the first 12 to 16 years of a girl’s life(44,45).

The specifics of oocyte (egg cell) developmentare described in chapter 3, but it is important tonote that there are fundamental differences be-tween the production of female germ cells (eggs)and the production of male germ cells (sperm).Because of these differences, exposure to agentsthat are toxic to reproductive cells has differentconsequences for women than for men.

In a female fetus, all primordial germ cellsprogress to the oocyte stage before birth.There is no further generation of oocytes. Anagent that is toxic to oocytes thus depletes a fi-nite supply. A male, by contrast, continues to gen-erate spermatogonia—the analog of the femaleoocyte—after he reaches reproductive maturity.From puberty onward, sperm cells are continu-ously produced from spermatogonia in a proc-ess that takes between 64 and 74 days. Contami-


nated spermatogonia are thus effectively “washed”from the system and replaced by fresh cells. This“cleansing” is obviously ineffective if exposure tothe toxin continues or if there is chromosomalor hormonal damage that prevents the genera-tion of healthy sperm (44).

Proper function of the developed ovary re-quires coordination of the hypothalamic-pituitary-gonadal axis; i.e., the correct balance of hormonesmust be present and the reproductive organsmust have the capacity to respond to hormonalactivity. The system relies on continual feedbackmechanisms that signal increases and decreasesin the production of particular hormones. Fluc-tuations in the concentration of these substances,in turn, cue the events of the menstrual cycle.Successful coordination of the hormonal andgrowth activities results in ovulation, the matu-ration and release of one egg cell approximatelyvry .28 davs (4,44). (See Tech. Note 14.).

Indi rec t Indica tors

Regular Menstruation.-A regular menstrualcycle is one of the best indicators that the hypo-thalamic-pituitary -gonadal axis is functioningproperly. Correct shifts in hormone concentra-tion, the formation of the follicle complex (con-taining the oocyte to be released), the growth ofthis complex, and the ultimate release of the ma-ture egg cell for passage to the uterus are all im-plied by the occurrence of menstruation (45). (SeeTech. Note 14.)

Hormone Levels.–Hormonal feedback mech-anisms are critical to ovarian function. Hormonesproduced outside of the ovary serve to stimulatethe organ’s production of additional hormonalsubstances. Each is necessary in order for theevents in the monthly cycle (e.g., maturation andrelease of an egg, uterine tissue growth) to oc-cur. Verifying the proper balance of and shiftsin the levels of these substances, therefore, servesas a strong indicator of ovarian function. Bloodserum and/or urine may be assayed for informa-tion on each of the relevant hormones. In addi-tion, a new method permits levels of one key hor-mone, progesterone, to be monitored in saliva(74). (See Tech. Note 15 and figure 5-8.)

Basal Body Temperature. -Normal fluctua-tions occur in a woman’s resting body tempera-ture throughout her 28-day cycle. Basal body tem-perature is thus a valuable indirect measure ofovarian activity. The temperature shifts can bemeasured and recorded by the woman herselfwith a standard oral or rectal thermometer. (SeeTech. Note 16, figures 5-8 and 5-9.)

Cervical Mucus. -Cervical mucus fills the cer-vical canal, the pathway from the vagina to theuterus. Samples can be collected quickly and eas-ily from the cervical opening. The quality andquantity of this mucus change over the courseof the menstrual cycle in accordance with estro-gen fluctuations. As a result, assessment of mu-cus quality and quantity indicates a woman’s men-strual phase. (See Tech. Note 17, figures 5-8 and5-lo.)

The changes that occur in conjunction with ovu-lation make it the only time of the menstrual cy-cle during which the mucus is penetrable bysperm. Observation of cervical mucus quality,particularly preovulatory mucus, is thus impor-tant in assessing female fertility (32,68).

Timed Endometrial Biopsy Adequacy of Lu-teal Phase.—Endometrial samples (tissue fromthe uterine wall) provide good evidence of ovar-ian activity and of the adequacy (length) of theluteal phase. The luteal phase, the portion of themenstrual cycle that occurs between ovulationand menses, is characterized by a thickening ofthe uterine wall tissue. A typical Iuteal phase isprecisely 14 days long. Deviation indicates a lu-teal phase deficiency (32,56,67). (See Tech. Note18, figures 5-8 and 5-9.)

Timed endometrial biopsy is the standard meansof identifying a luteal phase deficiency. * The pro-cedure examines tissue from the endometrium(uterine wall). Because thickening of the endome-trium is a regular occurrence of the menstrualcycle, a woman’s menstrual stage may be deter-mined based on the development of her endome-

● Progesterone levels also indicate luteal adequacy. This hormone,secreted after ovulation, stimulates endometrial cell growth dur-ing the luteal phase. Progesterone concentrations may be monitoredin blood serum and urine assays. An alternative method measuresprogesterone concentrations in saliva. (See Tech. Note 15a.)

Ch. 5—Technologies for Assessing Human Reproductive Function ● 1 4 3

Figure 5-8.—The Menstrual Cycle

Day 1 Day 14

FSHlevels

13

Estrogenlevels

LHlevels

Progesteronelevels

Fol l ic led e v e l o p i n gi n s i d eovary

Change incervicalmucus

Change inendometrium

Basaltemperature

I

II

SOURCE Reprinted from You Can Have a Baby. Illustrations by Della Malone Copyright1985 by Joseph H Bellina, M D., and Josleen

Wilson. Used by permission of Crown Publishers. Inc


Figure 5-9.—Basal Body Temperature Patterns Throughout the Menstrual Cycle

SOURCE: Reprinted from You Can Have a Baby. Illustrations by Delia Malone. Copyright O 1985 by Joseph H. Bellina, M. D., and Josleen Wilson. Used by permissionof Crown Publishers, Inc.

trial cells, and the date of her next menses maybe predicted. If menses occurs sooner or laterthan the expected date, a luteal phase deficiencyis identified (56,67). (See Tech. Note 19.)

Direc t Indica tors

Laparoscopy.—Direct observation of an ovaryto determine whether it has sustained structuraldamage or is deficient in oocytes requires an in-vasive procedure. The laparoscope is the opticalinstrument used to detect gross defects in ovar-ian structure (e.g., cysts, lesions). With the instru-ment inserted through a small incision in the ab-dominal wall, the ovaries are visible. Because itis an invasive procedure, laparoscopy is usuallyundertaken as a measure of last resort, when re-productive organ damage is suspected but hasbeen unidentifiable with standard clinical diag-nostic techniques. (See figure 5-I.)

Laparoscopic Ovarian Biopsy.—Observationof egg cells within the ovaries requires removaland microscopic observation of ovarian tissue.Tissue samples are taken with the laparoscopein place. While laparoscopic ovarian biopsy is a

surgical procedure, it is the only means by whichthe contents of the ovaries can be directly ob-served, By viewing the tissue sample under amicroscope, the presence of oocytes and of grow-ing follicles as well as the health of the ovariancells themselves can be verified (45). (See Tech.Note 20.)

Ultrasonography. -Ultrasonography is an im-aging technique by which ovarian activity can bemonitored. The projection of sonic waves into theabdominal region and the diagnosis of the wavereflections allows “visualization” of the underlyingorgans.

No adverse effects of ultrasonography havebeen demonstrated in humans. Moreover, mosthospitals and many physicians have the equip-ment necessary for the procedure. Ultrasound im-aging thus appears a safe and convenient meansto monitor ovarian activity, including folliculargrowth and ovulation (4,12). While clinical use ofultrasound for ovarian imaging is limited, thetechnique is widely used as a means of fetal im-aging during pregnancy. (See Embryonic Differen-tiation and Fetal Development. )

Ch, 5—Techno/ogjes for Assessing Human Reproductive Function . 145

Figure S-lO.—Cervical MUCUS Feming

Just prior to ovulation, cervical mucus dries in a ferning pattern.

SOURCE: L. Speroff, R. H. Glass, and N. G. Kase, Clinical Gyneco/ogic Endocrinology and /nferti/ify (Baltimore: Williams &Wilkins Co., 1978), p. 433,

Cervical Mucus

The receptivity of cervical mucus to sperm isa critical determinant of female fertility:

●

●

Cervical mucus quality varies in response tothe hormonal shifts of the menstrual cycle,making a woman’s mucus more receptive tosperm on some days than others. (See Ovar-ian Function: Indirect Indicators. )Certain agents may stimulate a woman’s pro-duction of sperm antibodies or change theconsistency or pH of her cervical mucus,making her reproductive tract unreceptiveto sperm.

Evaluating the compatibility of a woman’s cervi-cal mucus with her partner’s semen is thus animportant measure of a couple’s fertility (13).

Sperm-Cerv ica l MU C U S In terac t ion

Tests of sperm-cervical mucus interaction aredescribed earlier in this chapter (see Sperm Func-tion). Each examines the ability of the sperm topenetrate the mucus and sperm vitality after pen-etration (13,38)39). (See Tech. Note 10.)

Because of the fluctuations of both semen andcervical mucus quality, repetition of the test maybe necessary to confirm results. Cross-testing ofthe fluids with control samples—i.e., testing the

male’s semen against a standard cervical mucussample and the female’s cervical mucus againsta standard semen sample—is also useful. (SeeTech. Note 11.)

Limited sperm motility in cervical mucus mayindicate the presence of antisperm antibodies, ei-ther within the donor semen (autoimmunity) orin the reproductive tract of the female. Screen-ing for antisperm antibodies is particularly use-ful where sperm motility appears poor in cervi-cal mucus while semen analysis results arenormal, (See Tech. Note 2 and Tech. Note 12.)

Endometrial Cells

The capacity of the endometrial cells (cells lin-ing the uterus) to respond to monthly hormonalsecretions is an important component of femalefertility. Cyclic changes in hormone levels stimu-late endometrial cell proliferation each month,preparing the uterus for pregnancy.

Endometr ia l B iopsy

Appropriate endometrial growth is verifiedthrough microscopic observation of endometrialtissue. Tissue is extracted by endometrial biopsy,a procedure described earlier, (See Tests of Ovar-ian Function, and Tech. Note 19. ) observation ofendometrial cells also permits diagnosis of endo-


metrial infection or disease (e.g., endometritis)that could impair fertility.

Tubal Patency/Uterine Structure

The passage of a fertilized egg through the fal-lopian tubes and its implantation in the uterinewall are necessary for the establishment of preg-nancy. Verification of tubal patency and uterinestructure are, therefore, important aspects of afemale fertility evaluation.

Hysterosalpinggogram

Imaging of the uterus and fallopian tubes is pos-sible by injection of dye into the cervix and film-ing its spread through the peritoneal cavity. Theprocedure is safe and relatively painless. X-rayphotography of the dye dispersion indicates anyocclusion or convolution of the fallopian tubesthat might prevent passage of a fertilized egg tothe uterus. In addition, the size, shape, and posi-tion of the uterus and the presence of any abnor-malities in the uterine wall are discernible withthis technique (11,62,67).

Laparoscopy

If hysterosalpingography indicates normal tubaland uterine structure, laparoscopy may be use-ful. It affords the physician the opportunity fordirect observation of the peritoneal cavity. Theprocedure is described in the discussion of directmeasures of ovarian function (62).

Ul t rasound

Imaging of the peritoneal cavity using ultra-sound equipment may prove to be the preferredmethod of observation. The method is painlessand, to date, does not appear to be detrimentalin any way (12).

Implantation/Establishment ofPregnancy

There are no direct measures of gamete or zy-gote transport in humans. Consequently, theoccurrence of pregnancy is the only indicationthat fertilization, transport, and implantation havebeen successfully achieved (45).

Human Chorionic Gonadotropin (hCG)

Human chorionic gonadotropin (hCG) is a sub-stance that is secreted only during pregnancy.Blood and urine hCG assays are used to determinewhether pregnancy has occurred (25,67):

●

●

Presence of hCG in the blood serum is theearliest indication of pregnancy; i.e., it occursbefore a woman misses her menstrual period(25).Home pregnancy detection kits screen forhCG in the urine. While the tests claim a highdegree of accuracy and cost less than labora-tory blood serum assays ($10 as opposed to$30), pregnancy cannot be detected as earlyin urine assays as it can when blood serumis used. *

Because the amount of hCG in the blood followsa specific pattern over the course of the pregnan-cy (see figure 5-11), monitoring hCG is also use-ful in detecting pregnancy loss. Sudden drasticdecreases in hCG indicate that pregnancy loss hasoccurred. (See Tech. Note 21.)

Embryonic Differentiation andFetal Development

In-utero monitoring of embryo/fetal develop-ment is made possible by several clinical tech-niques, both invasive and noninvasive. Invasiveprocedures sample tissue and/or fluid in attemptsto diagnose systemic diseases or disorders in thedeveloping fetus. Noninvasive fetal monitoringcovers a broad range of procedures, includingseveral imaging techniques, designed to detectstructural abnormalities and/or physical manifes-tations of disease in the fetus or in the maternalreproductive tract. Damage to the mother or con-ceptus may be the result of any number of fac-tors (e.g., exposure to one or more reproductivehazards, injury, nutritional inadequacy). By af-fording prenatal diagnosis of damage and/or dis-ease, these methods contribute information thatmay be critical to appropriate management ofpregnancy.

*Human chorionic gonadotropin (hCG) is apparent in the bloodserum about 15 days after conception (i.e., about the time the men-strual period is expected), while it is not apparent in the urine un-til 4 to 6 weeks after conception.


Figure 5.11 .—Mean Human Chorionic Gonadotropin(hCG) During Pregnancy

n I-4

I

u4 8 12 16 20 24 28 32 36 40

Weeks after last menstrual period

SOURCE: A.C. Wentz, J.R. Givens, R.N. Anderson, et al., &farrua/ ofGyrreco/ogic Endocrinology and /nfert///ty (Baltimore: Williams &Wllklns Co., 1979).

A m n i o c e n t e s i s

The amniotic sac is the fluid-filled cavity thatsurrounds the developing fetus. (See figure 5-12.)Amniocentesis is the extraction of amniotic fluidfor diagnostic purposes. * The fluid contains somelive cells shed by the fetus. Both the fluid itselfand the cells within it provide important infor-mation about the fetus.

Amniotic cells are used primarily to diagnosechromosomal anomalies and genetic disorders:

●

●

Disorders caused by aberrant chromosomestructure or number (e.g., Down syndrome,Turner syndrome, Klinefelter syndrome)may be diagnosed by karyotyping’ * amnioticcells. (See Tech. Note 22.) Fetal sex is alsoapparent in the karyotyped cells.Several genetically based diseases—diseasescaused by errors ‘in the genetic informationin a particular chromosome—(e.g., Tay Sachs,sickle-cell anemia, hemophilia) may be diag-nosed using newly developed techniques.(See Tech. Note 23.) These are not routinelyincluded in the analysis of amniotic cells, butare useful where specific genetic diseases are

*The fluid is extracted by means of a needle that is insertedthrough the abdomen into the amniotic cat’it~’.

* ● KarYotYping is a technique bjr which chromosomes are pre-pared for microscopic observation. It is a standard part of am-niocentesis, [See Tech. Note 21. )

Figure 5-12.—Amniotic Cavity

I

Amniocentesis at 16 to 17 weeks.SOURCE: Adapted from J T Queenan, “In Uterine Diagnosis of Down Svndrome,”

Annals of NY Academy of Sciences 171 :6?7, 1970.

likely (e.g., one or both parents suffer froma particular hereditary disorder). * * *Enzyme and protein assays of amniotic cellsmay identify certain other physiological dis-orders in the developing fetus. (See Tech.Note 24.) These assays are generally reservedfor instances in which the presence of oneof these disorders is suspected.

Amniotic fluid provides additional informationabout fetal health:

● The fluid is most commonly assayed for thesubstance alpha-fetoprotein (AFP). Abnormal-ly high levels of AFP are associated with dis-orders of the central nervous system, particu-larly neural tube defects (e.g., anencephaly,spina bifida). Elevated AFP may also reflectother systemic disorders. (See Tech. Note 25.)

* * *Amniocentesis is considered a far safer diagnostic techniquethan those previously used to detect genetic disorders (e.g., fetaltJ]OOd sampling to detect hemophilia, sickle-cell anemia, and otherhereditary blood diseases).

38-748 0 - 85 - 6


● Hormone assays of the amniotic fluid are nota routine part of amniocentesis, but may beuseful in diagnosing certain hormonal disor-ders in the fetus. (See Tech. Note 26.)

Amniocentesis is usually performed about mid-pregnancy (see Tech. Note 27) and is believed toinvolve a risk to the fetus of less than os per-cent (31). It has become relatively standard in theunited States to offer the procedure to pregnantwomen over age 35* and to those at risk for cer-tain fetal abnormalities. Table 5-2 outlines the sit-uations for which amniocentesis is recommended.

F e t o s c o p y

The fetoscope is an optical instrument that al-lows direct observation of the fetus. Fetoscopyis an invasive procedure, like amniocentesis, butit presents a higher level of risk to both the preg-nant woman and the fetus because the instrument

*,4mniocentesis is advised for women who become pregnant dur-ing or after their mid-30s because there is an increased risk of Downsyndrome associated with advanced maternal age.

Table 5-2.—Circumstances for Which Amniocentesisis Recommended

1,2,

3,

4.

5.6.

7.

8.

9.

10.

Pregnancies in women 35 years of age or older.A previous pregnancy resulting in the birth of a chro-mosomally abnormal offspring.Chromosomal abnormality in either parent, including:a. balanced translocationa carrier stateb. aneupoloidyb

c. mosaicismc

Down syndrome or other chromosomal abnormality ina close family member.Pregnancy after three or more spontaneous abortions.A previous infant born with multiple major malforma-tions on whom no cytogenetic study was performed.Fetal sex determination in pregnancies at risk of a se-rious X-linked hereditary disorder.Biochemical studies in pregnancies at risk of a seri-ous autosomal or X-linked recessive disorder.A previous child or a parent with a neural tube defector routine screening finds maternal serum aipha-feto-protein level to be abnormally high.Confirmation of certain abnormalities noted in asonogram.

aTh e shifting of a segment of one chromosome into another chromosome that

does not result in any excess or lost genetic material.bAn y deviation from the correct number of chromosomes.cThe presence in an individual of two distinct cell lines fOr a Single characteris-tic (e.g., two blood types).

SOURCE: Adapted from: J. A. Pritchard, P. C. MacDonald, and N. F. Grant, “Tech-niques to Evaluate Fetal Health, ” kVi//iarns Obstetrics (Norwalk, CT:Appleton-Century-Crofts, 1965), pp. 267-293.

is much larger and remains inserted for 15 to 45minutes (42). The procedure is associated with arisk to the fetus of approximately 20 percent. Con-sequently, clinical use of this technique is ex-tremely rare,

Nonetheless, fetoscopy can provide some infor-mation that amniocentesis and other diagnosticprocedures cannot. Several congenital disordersthat are not detectable through analysis of amni-otic fluid and cells, for example, can be identifiedthrough fetoscopy, which allows direct samplingof fetal blood and/or tissue (24). Tissue samplesmay identify the presence of disease in the biop-sied organ, while analysis of fetal blood may de-tect hemophilia or various hemoglobinopathies(deficiencies of the hemoglobin) (42).

The three uses for fetoscopy include:

1. viewing the fetus,2. sampling fetal blood and/or tissue, and3. in-utero therapy.

Because noninvasive imaging techniques (e.g.,ultrasound) exist and appear to be safer, fetoscopyis rarely used where observation of the fetus isthe sole aim. (See Tech. Note 28.)

Chorionic Villus Biopsy

Chorionic villus biopsy is a method of prenatalmonitoring that permits early identification of var-ious disorders, particularly genetically based dis-eases (e.g., hemophilia, sickle-cell anemia). Thechorion (the membrane that encases the amnioticsac containing the developing fetus) is comprisedof cells derived from, and thus genetically iden-tical to, the fetal cells (57). (See figure 5-13.)

Analysis of chorionic tissue provides the sameinformation as amniotic fluid and cells (53). Theimportant advantage of chorionic sampling is thatit can be done much earlier in pregnancy thanamniocentesis or biopsy of other fetal tissues.Chorionic villus biopsy is, in fact, the only methodfor diagnosis of genetic disorders that can be per-formed in the first trimester of pregnancy. Bothamniocentesis and fetoscopy require that the fe-tus be in at least the second trimester of gesta-tion (57).

The degree of risk posed by the procedure isuncertain. Preliminary data indicate a high rate

Ch. 5—Technologies for Assessing Human Reproductive Function 149

Figure 5-13.–Chorionic Villus Biopsy

Cv

(I2 percent) of fetal loss following chorionic villusbiopsy (27). However, because the procedure isperformed during the first trimester, duringwhich time a high incidence of spontaneous abor-tion is normal, the post-biopsy losses may be at-tributable to normal early fetal loss rather thanto the procedure itself (27)57). Since the actualdegree of risk associated with chorionic biopsyhas not been established, those who choose to un-dergo the test must weigh the limited informa-tion about its dangers against the advantage ofhaving a first-trimester prenatal diagnosis (54).

Ul t rasonography

Ultrasound, described earlier in conjunctionwith assessment of ovarian and uterine activity,is an extremely useful method of analyzing em-bryo/fetal development. The procedure relies ondifferences in acoustic densities for informationabout the status of the uterus and its contents.To date, no adverse effects in humans have beenfound to be caused by ultrasonography (12). Con-sequently, it has largely replaced the use of X-rayin obstetrics (53).

Sonographic Imaging. -Over the course ofpregnancy, ultrasound imaging affords a vastrange of diagnostic possibilities:

●

●

●

●

●

●

Early use of ultrasound can detect ectopicpregnancies and assess gestational age. (SeeTech. Note 29.)Beginning the seventh week of gestation, ul-trasound imaging enables the embryonalheartbeat to be “visualized.”In the second trimester, ultrasound allows de-tection of gross fetal malformations (e.g.,anencephalies), multiple pregnancies, placen-tal localization, progression of fetal growth(26,31,55).In the late stages of pregnancy, ultrasonog-raphy is useful for monitoring fetal breath-ing, trunk and limb movement, filling andemptying of the bladder, and quantity of am-niotic fluid (53).Ultrasound imaging equipment may be usedin conjunction with other fetal diagnosticmethods; e.g., to ensure proper placement ofthe needle in amniocentesis.Ultrasound imaging facilitates delivery of afetus whose presenting part cannot be ade-quately determined during labor.

Table 5-3 provides a more detailed descriptionof the range of uses for ultrasound in obstetrics.

Its safety and potential for identifying fetal ab-normalities and for providing reassurance of fe-tal well-being make ultrasonography an attractivediagnostic technique. In parts of Western Europeand Scandinavia, ultrasonic surveillance is con-sidered a standard component of obstetric care.The procedure is not, as yet, routine in the UnitedStates, however, partly because of its cost (approx-imately $125).

Monitoring the Fetal Heart Rate.—-[n additionto the use of diagnostic ultrasound, ultrasoundequipment is routinely used to monitor fetal heartrate. (See Tech. Note 30.) Response of the fetalheart to uterine contractions and to fetal move-ment has been identified as an indication of fetalwell-being. The hand-held ultrasound device isalso used to monitor fetal heart rate during la-bor and delivery.


Table 5-3.-Use of Ultrasound in Fetal Monitoring

1. Very early identification of intrauterine pregnancy.2. Determination of gestational age: permits proper timing

and management of delivery.3. Identification of multiple fetuses, including conjoined

twins.4. Demonstration of the size and the rate of growth of the

amniotic sac and the embryo, and, at times, resorptionor expulsion of the embryo.

5. Measurements of the fetal head, abdominal circum-ference, and femur (the bone that extends from the pel-vis to the knee), to help identify the duration of gestationfor the normal fetus or, when measured sequentially, tohelp identify the growth-retarded fetus.

6. Comparison of fetal head and chest or abdominal cir-cumference to identify hydrocephaly (accumulation offluid in the cranium), microcephaly (abnormal smallnessof the head), or anencephaly (congenital absence of thecranial vault, with brain missing or drastically reduced insize).

7. Detection of fetal anomalies such as abnormal distentionof the fetal bladder, ascites (accumulation of serum in theabdominal cavity), polycystic kidneys, renal agenesis (fail-ure of kidney to form), ovarian cyst, intestinal obstruction,diaphragmatic hernia, meningomyelocele (protrusion ofbrain membranes and part of the spinal cord through adefect in the vertebral column), or limb defects.

8. Demonstration of hydramnios (excess amniotic fluid), oroligohydramnios (inadequate levels of amniotic fluid) bycomparing the size of the fetus to the amniotic fluid sur-rounding the fetus.

9. Identification of the location, size, and “maturity” of theplacenta.

10. Demonstration of placental abnormalities such as hydati-diform mole (pregnancy abnormality resulting in a massof cysts resembling a bunch of grapes), and anomaliessuch as chorioangioma (tumor of the chorion).

11. Identification of uterine tumors or anomalous devel-opment.

12. Detection of a foreign body such as an intrauterine device,blood clot, or retained placental fragment.

13. Monitoring fetal movement, including fetal heartbeat,breathing, trunk and limb movement, bladder function.

14. Adjunct to amniocentesis: guidance of the needle to avoiddamage to placenta and/or fetus.

15. Adjunct to special procedures such as fetoscopy, intra-uterine transfusion, and chorionic villus biopsy.

16. Follow-up observation of fetal anomaly identified by someother method; e.g., screening for anencephaly where am-niocentesis indicates elevated alpha-f etoprotein levels.

17. Determination of fetal presentation to facilitate delivery,particularly when the presenting part cannot be adequate-ly determined in labor or the fetal presentation is varia-ble in late Precmancy.

SOURCE: Adapted from: J. A. Pritchard, P. C. MacDonald, and N. F. Grant, “Tech.niques to Evaluate Fetal Health, ” bV///iarns Obstetdcs (Norwalk, CT:Appleton-Century-Crofts, 1965), pp. 267-293; and Consensus Confer-ence, “The Use of Diagnostic Ultrasound Imaging During Pregnancy,”Journal of the American Medical Association 252:669-672, 1964.

x-nay Radiography

Use of diagnostic radiography in obstetrics hasbecome limited for several reasons:

●

●

●

Some evidence suggests a correlation be-tween prenatal exposure to ionizing radiationand fetal defects (e.g., chromosomal damage,childhood cancer).Uncertainty regarding the effects of the radi-opaque dyes used to enhance fetal imaginghas raised concern (10). *Most of the measurements made radiographi-cally (e.g., skeletal malformations, neural tubedefects, gastrointestinal obstructions, fetal tu-m ors) can also be made using ultrasound, amethod for which no correlation with fetaldamage has been identified (12,53).

Despite these concerns, limited use is still madeof radiography in obstetrics, particularly in thethird trimester of pregnancy, when evidence sug-gests the fetus may be least susceptible to radio-logically induced defects (10,66). Pelvimetry (X-ray of the pelvic region), for example, may helpto determine the need for cesarean section whena breech (bottom-first) presentation of the fetusis discovered during labor.

Nuclear Magnetic Resonance

Nuclear magnetic resonance is a method of or-gan and body imaging that may become an im-portant obstetric tool once its safety during preg-nancy can be established (53). Its utility for inutero observation of structure and function hasalready been documented (60,63).

Delivery and Lactation

Several toxic agents can affect the ease and tim-ing of parturition. Techniques for monitoring thestatus of the fetus during labor and delivery,

*Visibility of the fetus is often enhanced through instillation ofwater-soluble (amniography) or lipid-soluble (fetography) dyes intothe amniotic fluid that surrounds the fetus (10,40).


aimed at early identification and relief of fetal dis-tress, may provide important insights into the im-pact of various exposures on these aspects of re-production (45).

In most pregnancies, basic clinical monitoringof the fetal heart rate, frequency of uterine con-tractions, and rates of cervical dilation and de-scent of the fetus is adequate. The fetal heart rateis monitored using either a specialized stetho-scope or a hand-held ultrasound device. The heartrate is measured either intermittently or continu-ously, with emphasis on the rate during and im-mediately following uterine contractions (53).

Continuous electronic monitoring of fetal heartrate and/or uterine pressure is indicated for cer-tain conditions; e.g., maternal diabetes, previousunexplained stillbirth, induction of labor. Theelectronic equipment used for these procedures,however, requires invasion of the uterus and maypose some risk to the fetus (e.g., trauma, infec-tion) (53).

Measuring fetal blood pH at regular intervalsduring labor and delivery also provides an indi-cation of fetal well-being. Like electronic moni-toring, however, it is reserved for specific in-stances because the taking of the sample maycause trauma, infection, or damage to the fetus(53).

Lac ta t ion

A woman’s ability to produce and secrete milkmay be adversely affected by certain toxic ex-posures. Competence of lactation is an importantindicator of such damage (45). In addition, sev-eral substances have been found to contaminatethe milk produced by women exposed to them.In such instances, chemical analysis of milk con-tent may be necessary to verify its suitability forconsumption.

Chemical Content of Milk. --Chemical analysisof milk content provides information on the pres-ence of toxins that may pass to the infant duringmaternal feeding. Various chemical assay meth-ods (e.g., gas chromatography and high pressureliquid chromatography) are available. Dependingon the compounds involved, different techniquesare appropriate (69). Procedure costs vary by sev-eral orders of magnitude (i.e., from $5 to $5,000)depending on the substance for which the screen-ing is done. To date, chemical analysis of mater-nal milk is undertaken only when there is rea-son to believe that the milk source may becontaminated at levels sufficient to affect thenursing infant.

CONCLUSION

While there are several methods by which toestimate individual reproductive capacity, phys-ical examination and laboratory analyses can onlydetermine that a manor woman is potentially fer-tile. Fertility is a product of the specific interac-tion of a particular couple. Evaluation and treat-ment of infertility, therefore, must consider thecouple as a unit.

Furthermore, a thorough assessment of repro-ductive capacity cannot be limited to an evalua-tion of reproductive organs and reproductive cells(sperm and eggs). The multitude of parametersthat comprise reproductive health are inextrica-bly related to other physiological systems. Physi-cal examination of the fertility patient, for exam-ple, must include assessment of circulatory, endo-

crine, and necrologic function. Oral or writtenhistory-taking must consider a broad range ofmedical factors and lifestyle characteristics thatmay influence reproductive health. In conjunc-tion with the appropriate laboratory analyses,these may contribute critical insights into thecause, diagnosis, and appropriate treatment of re-productive impairment.

Examination of the male fertility patient is sim-plified by the fact that his reproductive organsand germ cells (sperm) are readily accessible. Thefemale correlates are not. However, while semenanalysis”does permit evaluation of several aspectsof male reproductive function (e.g., ejaculatorycapacity)) and of semen quality and quantity)there remains no positive method by which to dif-


ferentiate fertile and infertile sperm. Female re-productive health can be estimated through avariety of indirect indicators (e.g., menstrual regu-larity, hormone levels, cervical mucus properties)and direct methods (e.g., tissue biopsy, laparo-scopy, ultrasound imaging). None of these, how-ever, constitutes absolute evidence of a woman’sability to conceive or to maintain a pregnancy.

No diagnostic method, in fact, provides positiveverification of individual reproductive capacity.Even techniques that consider the interaction andcompatibility of a couple as a unit (e.g., sperm-cervical mucus interaction) cannot confirm theirability to generate healthy offspring. Successful

reproduction is the only absolute verification ofa couple’s reproductive potential.

The development of additional clinical methodsmay advance the evaluation of infertility and thein-utero diagnosis of fetal abnormalities, but mon-itoring their incidence in the population will con-tinue to be important. Changes in frequency ofreproductive difficulties (e.g., infertility, frequentmiscarriage, premature birth, structurally and/orfunctionally impaired offspring) can provide in-sights into their causes, thus helping to identifythose factors (i.e., workplace exposures, lifestylecharacteristics) that impair human reproductivecapacity.

TECHNICAL NOTES

1. Leutinizing hormone (LH), follicle stimulating hor-mone (FSH), and testosterone are the hormones mostfrequently measured in the male. The proper balanceof these substances in the bloodstream is critical tothe entire range of reproductive functions. (See chap-ter 3.)

2. Antisperm antibodies in the male seminal fluid orblood serum (autoimmunity) can result in reduced fer-tility or infertility. Where sperm agglutination occurswith no evidence of bacterial infection, antibody test-ing may reveal autoimmunity. Various illnesses andsurgical procedures (e.g., vasectomy, hernia repair,testicular infection, mumps, prostatitis) alert the phy-sician to the possibility of antisperm antibodies. A sim-ple test, combining semen, antibody-treated blood se-rum, and antibody compounds, detects the presenceof antisperm antibodies in the semen (i.e., if it carriesantisperm antibodies, sperm will adhere to the anti-body-treated blood serum) (28). An alternative methoduses immunobeads, compounds to which antispermantibodies adhere. By suspending sperm in a solutionof immunobeads, sperm to which antibodies havebeen bound are identifiable (9). (See Tech. Note 11.)

Antisperm antibodies can also occur in the female,causing impaired fertility. Where sperm of good qual-ity show poor interaction with cervical mucus in thepost+oital test, it is important to screen both the maleand female for antisperm antibodies.

3. The first study to correlate sperm density withfertility cited 20 million sperm per milliliter of semenas the lower limit of a “normal sperm count .“ This find-ing was based on a comparison of sperm density in

1,000 fertile and 1,000 infertile men. The researchernoted that those identified as infertile frequently hadsperm counts below the 20 million level (41).

Subsequent studies, however, demonstrate thatpregnancy can occur even when the sperm densityis well below that level. There remains no uniformlyaccepted specification of the number of sperm per mil-liliter of semen necessary to establish fertility (23,71).

4. Testicular biopsy is the surgical removal of awedge of testicular tissue for analysis. Where normalspermatogenesis (sperm production) is occurring, mi-croscopic observation of the tissue should disclose allstages of growth-from immature spermatocytes tomature sperm.

Lasography describes X-ray imaging of the ejacula-tory tract following instillation of radio-opaque dye inorder to locate any obstruction of the ejaculatory ducts(59).

5. In the visual rating system commonly used in lab-oratory motility assessment, semen is examined micro-scopically and the number of motile sperm in severalareas of the microscopic slide is used to estimate theoverall percentage of motile sperm in the semen. In-dividual sperm are often scored according to the fol-lowing scale (23):

O =No progression1 =Weak forward progression2 =Moderate forward progression3 =Active forward progression

The extreme subjectivity of these ratings makes com-parison of motility data from different laboratoriesproblematic.


6. Videomicrography. Videomicrography is a re-.cently developed technique that improves objectivityin assessing sperm motility. A video camera mountedon a microscope is used to record sperm activity. Thedistance traveled per second (swimming speed) by in-dividual sperm is determined using a metered view-ing screen. The percentage of motile sperm in the to-tal sample can also be estimated by this method (37).

7. Single Image Photomicrography/High Speed Cin -emicrographey. Single image photography permits ob-servation of sperm movement. Forwardly progress-ing sperm appear as streaks in the time-exposed photo-graph. (See figure s-4.) The swimming speed of thesecells is determined by the length of the “streak” in re-lation to the time of the photographic exposure (e.g.,25 micrometers per second) (29,43,50).

8. Automated Analysis. To further reduce humanerror and subjectivity in analysis of sperm movement,automated techniques have been introduced. Theserely on computerized scanning and evaluation of photo-graphic images to determine individual sperm veloci-ties and the percentage of motile sperm in a sample(2,34).

9. Reference slides (70) and morphology` overlays (36)are two recently developed methods that attempt tostandardize morphology assessment. These establishcategories (e.g., narrow head, large head, pear-shapedhead) and provide standards against which to meas-ure sperm (36,70). (See figure 5-7. )

An alternative approach is to perform direct mor-phometric measurement (i.e., length, width, area, cir-cumference) of at least 50 sperm from a sample. Ini-tial studies suggest that morphologic consistency ofthe sperm in a sample may correlate with fertility(35,58).

10. In the post-coital test, sperm are observed in acervical mucus sample taken shortly after intercourse.An alternative method obtains separate samples ofsemen and cervical mucus and combines them in thelaboratory to observe their interaction. Results of thepost-coital sperm-cervical mucus interaction test docorrelate with fertility (21).

11. The semen of the male partner can be testedagainst a standardized cervical mucus sample (e.g., bo-vine and synthetic mucus are under study); while thewoman’s cervical mucus can be tested for its recep-tivity to a semen sample of good quality. This enablesthe physician to determine whether the couple’s fer-tility problem is attributable to one of the two part-ners or is the result of a compatibility problem.

Semen: male patient Cervical mucus: female

x patient

Semen: control specimen Cervical mucus: controlspecimen

12. Studies indicate that antisperm antibodies canbe categorized according to their binding point onsperm. Those that bind to the head region appear tobe most obstructive to sperm penetration of cervicalmucus and/or zona pellucida of the egg cell, while tail-binding antibodies may impair sperm motility. One re-cently developed method enables the site of sperm-antibody binding to be identified. The technique usesimmunobeads, compounds that adhere to antispermantibodies. By suspending sperm in a solution of im-munobeads, sperm to which antibodies have beenbound are identifiable (9).

13. The zona-free hamster egg penetration test ex-amines the ability of human sperm to penetrate ham-ster eggs from which the outer layer—the zona pel-lucida—has been removed. The zona pellucida is themajor barrier to fertilization between animals ofdifferent species (1).

A substantial weakness of the testis that sperm thatare able to penetrate a zona-free hamster egg may beunable to fertilize a human egg with its zona pellucidaintact. The result is that men who have demonstratedfertility problems may appear normal in the zona-freehamster egg test. Studies note the occurrence of such“false positive” results (51). The test may also show“false negative” results, indicating infertility in maleswho have recently fathered children (19).

Studies show that penetration rates of sperm fromfertile men range from 11 percent to 100 percent insperm-egg penetration tests (l). Researchers disagreeas to what constitutes “normal sperm penetration. ”Some identify a male as fertile if 90 percent of hissperm successfully penetrate the test egg, while othersconsider a single penetration an indication of repro-ductive competence (19).

14. There are exceptional cases, such as the eventof an anovulatory cycle—menstruation occurring with-out an egg passing to the uterus. In most instances,however, regularity of menstruation is an indicatorof reproductive health.

15. Assay of salivary fluids for progesterone hasbeen suggested as an alternative to blood serum as-says for this hormone. The method is particularly ad-vantageous where serial sampling is required to mon-itor daily fluctuations in progesterone levels. Becauseadequate Iuteal function is reflected by ovarian secre-


tion of progesterone, the technique may also be use-ful in identifying Iuteal phase deficiency (74).

16. The increase in progesterone production that fol-lows ovulation causes a rise of 0.5 to 1.OO in basal bodytemperature. These temperature shifts can be meas-ured and recorded by the woman herself with a stand-ard oral or rectal thermometer. Because the basal tem-perature reflects the lowest or resting temperature,she must take the reading immediately on waking inthe morning, before arising from bed (56,67).

Although problems with the reliability of this meth-od have been identified, many laboratories believebasal body temperature to be an extremely sensitiveand accurate indicator of ovulation. They base the tim-ing of subsequent fertility assays on the occurrenceof these temperature shifts.

17. The large quantity of estrogen present immedi-ately before ovulation stimulates increased productionof cervical mucus (from 20 to 60 mg/day to 200 to 700mg/day) (73). This mucus has particular characteris-tics that identify it as “preovulatory mucus.” It is morewatery, less viscous, and displays a “fern” drying pat-tern due to the crystallization of salt on the mucus fila-ments (see figure 5-10) (6,56,67).

18. A typical luteal phase is precisely 14 days long.Variation among women in length of menstrual cyclesis usually due to differences in the number of dayspreceding ovulation while the luteal phase remains 14days in most women. Deviation indicates a Iuteal phasedeficiency (56,67).

19. In endometrial biopsy, uterine tissue samples areobtained by scraping the uterine wall with a small in-strument inserted in the endocervical canal. Micro-scopic observation of the endometrial cells verifies cellproliferation in response to monthly hormonal se-cretions.

The degree of endometrial cell development indi-cates a woman’s menstrual stage and allows the dateof her next menses to be predicted. For example, ifthe endornetrial tissue obtained in the biopsy showsdevelopment characteristic of the 22nd day of the cy-cle, menstruation should occur 6 days later (i.e., onthe 28th day). If menses occurs sooner or later thanthis expected date, a luteal phase deficiency is identi-fied (56,67).

20. The tissue samples taken in a laparoscopic ovar-ian biopsy represent only a minute area (0.5 centime-ters) of the ovary. Other regions of the organ may varyconsiderably. Thus, even ovarian biopsy cannot pro-vide a complete image of the ovary and the numberof oocuytes it contains.

21. Identification of pregnancy through hCG moni-toring is most useful in the case of early pregnancylosses, which are otherwise difficult to detect (i.e., lossbefore pregnancy is visibly apparent). Some findingsindicate that as many as 70 percent of all pregnanciesare lost before the pregnancy itself is recognized. Thisis due, in part, to the amount of time that may elapsebefore a woman realizes that she is pregnant. BecausehCG monitoring provides earlier indication of preg-nancy, it could prove useful in establishing more ac-curate estimates of early pregnancy loss rates (16,25).

22. In karyotyped amniotic cells, numerical aberra-tions (more or less than the standard 46 chromosomes)as well as structural abnormalities (deleted or mis-placed regions of the chromosomes) that result in ab-normal formations (e.g., rings, fragments, chromo-somes with obvious lesions) are detected (31). Severalhuman disorders (e.g., Down syndrome, Turner syn-drome, and Klinefelter syndrome) are known to re-sult from these chromosomal anomalies.

23. Recently developed techniques enable a numberof genetically based diseases (i.e., diseases caused byerrors in the genetic information in a particular chro-mosome) to be diagnosed using amniotic cell chromo-somes. The most common of these is a genetic map-ping technique that uses enzymes (restriction endo-nucleases) known to cleave DNA in specific code loca-tions. Chromosomes bearing properly coded genesyield a particular pattern of fragments when cleavedby the enzymes, while chromosomes with alternateforms of these genes are cleaved differently (14,47,48).Some diseases that are the result of a faulty gene (e.g.,Tay Sachs, sicklesell anemia, hemophilia) are identifi-able with this method.

24. Enzyme and protein assays of amniotic cells areanother means of diagnosing certain disorders in thedeveloping fetus. Presence of one protein (the glial pro-tein S-1OO), for example, indicates the likelihood of acentral nervous system defect, while enzyme assayscan detect certain metabolic disorders, such as the in-ability to digest specific amino acids, lipids, or sugars(31). These assays are generally reserved for instancesin which the presence of one of these disorders is sus-pected.

25. Alpha-fetoprotein (AFP) is a protein synthesizedby the fetus and present in the amniotic fluid in con-centrations that decrease with gestational age. Deter-mination of AFP levels is a standard part of amniocen-tesis. Abnormally high levels of AFP are associatedwith disorders of the central nervous system, particu-larly with neural tube defects (e.g., anencephaly, spina

Ch. 5—Technologies for Assessing Human Reproductive Function 155

bifida). Elevated AFP levels (greater than 20 milligramsper milliliter) may reflect other disorders, such as atre-sias (abnormal closures) of the digestive tube, polycys-tic kidneys, annular (ringlike) pancreas, hydrocepha-IUS (accumulation of fluid in the cranium), and Fallot’stetralogy (congenital cardiac defects).

26. Proper gonadal development in the fetus re-quires the appropriate balance of gonadotropins andsteroid hormones. The levels of these substances maybe determined by analyzing the amniotic fluid (31).

27. Amniocentesis performed earlier than the 16thweek often fails because of difficulties in obtaining anadequate amount of amniotic fluid and in successfullyculturing the amniotic cells during the first trimesterof pregnancy (24).

28. Uses of fetoscopy include:● Viewing the Fetus:-The small lens of the fetoscope

allows detailed observation of approximately 2 to4 square centimeters of the fetus at one time (42).This facilitates prenatal diagnosis of major exter-nal morphological malformations including facialclefts, deformed ears, limbs, and genitalia. Be-cause noninvasive imaging techniques (e.g., ultra-sound) exist and appear to be safer, fetoscopy israrely used where observation of the fetus is thesole aim. The limited size of the fetoscope fieldprevents visualization of the fetus as a whole. Itcannot be used to assess such things as limb size,thoracic volume, and overall anatomical sym-metry (42).

Sampling Fetal Tissue: The most substantial ben-efit that fetoscopy provides is that it permits ac-cess to fetal blood and tissue (24). Samples of theblood, skin, and/or liver tissue are taken with thefetoscope in place. Tissue samples may identifythe presence of disease in the biopsied organ,while analysis of fetal blood may detect hemophiliaor various hemoglobinopathies (deficiencies of thehemoglobin) (42). Further development of fetalblood assays may permit prenatal diagnosis of en-zyme deficiencies, nutritional and metabolic dis-orders, and blood cell diseases (24).Therapeutic Uses: Development of therapeuticuses of fetoscopy, such as blood transfusions toimmunodeficient fetuses, may make it a valuablemethod for early diagnosis and correction of fe-tal disorders (24). Present use of fetoscopy, how-ever, remains limited by the level of risk posedto the developing fetus (42).

29. A delivery that is too early or too late may jeop-ardize the fetus. Accurate estimations of gestationalage made with ultrasound are useful in determiningproper timing and management of delivery (i.e., in de-termining the need to suppress or to induce labor).

30. In the Contraction Stress Test, uterine contrac-tions are stimulated (e.g., by injection of oxytocin) andthe fetal heart response monitored with ultrasoundequipment. The Nonstress Test uses ultrasound to re-flect the fetal heart response to fetal movement asidentified by the mother (53).

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