8/18/2019 toag.5.1.50

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Answers t o Questions for Volume

4,

Number 3

Numbered references correspond

with

th e citations

in

th e original articles and

so

are

not

listed here.

References in roman numerals are

not

listed

in

th e origina l article; instead they can be found at the end

of

each set

of

answers.

Complications

of

assisted reproductio n

Ovarian hyperstimulation syndrome

(OHSS)

1 is commonly associated with the use of oral ovulation

induction agents.................................................. FALSE

2 increases in incidence with age. .........................

FALSE

3

in

i t s

mild form, occurs in more than

50

of

in

vitro

fertilisation (IVF) treatment cycles

...................... FALSE

4 i s

more likely to increase in severity

if

pregnancy

ensues. ................................................................... TRUE

5 in association with IVF can be reduced by using

progesterone for luteal support.

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

TRUE

Discussion

OHSS is

a

potentially life-threatening complication

classically associated with ovarian stimulation using

gonadotrophins.

It

rarely occurs with the administration of

oral ovulation induction agents such as clomiphene citrate.

Risk factors for the development of OHSS include: young

age, low body weight, polycystic ovaries, high dose of

gonadotrophins, large number of oocytes retrieved, high

oestradiol level on the day of human chorionic

gonadotrophin (hCG) administration, use of hCG for luteal

support, and ensuing pregnancy.2 OHSS may be classified as

mild, moderate or severe according to the Golan

classification.6Mild OHSS occurs in

23-33

of treatment

cycles, moderate in 3 6 of cycles and severe in 0.3-0.5 .'

Using progesterone for luteal-phase support rather than

hCG reduces the incidence of OHSS withou t having a

negative effect on pregnancy rates.'*

Regarding the management of

OHSS,

6 biochemical consequences include hypokalaemic

acidosis

.................................................................. FALSE

7 paracentesis i s contraindicated for symptomatic relief

of ascites. ..............................................................

FALSE

8 intravenous diuretics are indicated if the urinary

output is less than 30 ml/hr. ................................

FALSE

9

thromboprophylactic measures should be employed

for patients admitted to hospital.

....................... TRUE

10

physical exercise may increase the risk of ovarian

torsion

.................................................................... TRUE

Discussion

OHSS is associated with increased capillary permeability

and leakage of protein-rich fluid from the intravascular

space, which results in haemoconcentration and ascites.

Haematological and biochemical consequences include an

increase in haematocrit, leukocytosis, hyponatraemia and

hyperkalaemic acidosis. Correction of the hypovolaemia by

intravenous infusion will restore renal perfusion and,

hence, urine production. Diuretics are contraindicated.

They induce

a

diuresis by removing fluids from the

intravascular compartment and have no effect on the

ascites or the course of the disease.

Heparin (either conventional or low molecular weight)

and antiembolic stockings should be prescribed as

prophylaxis against deep venous thrombosis. Paracentesis,

carried out either transabdominally or transvaginally, is

indicated for symptomatic relief of large volumes of ascites.

In addition to symptomatic relief, this also results in

improved renal function, improved blood osmolarity,

reduced haemoconcentration and reduced pulmonary

compromise. Patients should be advised to avoid strenuous

activity, which increases the risk of ovarian torsion.

However, complete bed-rest should be avoided

as

it

increases the risk of thromboembolism.

With re ard to early pregnancy loss associated with

assistec reproduction,

11

there is an increased rate compared to natural

conception. ............................................................ TRUE

12

embryo transfer techniques may contribute to an

increased risk of ectopic pregnancies. .................

RUE

13 heterotopic pregnancy rates are in the region of 5 .

.............................................................................. FALSE

14 bilateral salpingectomy

is

recommended to reduce

the risk of ectopic pregnancy in patients undergoing

IVFACSI..................................................................

FALSE

Discussion

The apparent increase in miscarriage associated with IVF

appears t o be multifactorial, wi th infert ilit y itself,

regardless of cause, being of major significance.

Miscarriage rates as high as

28

have been reported in

infertile women who conceive spontaneously.

The ectopic pregnancy rate varies between

2-11

in

reported series of IVF pregnancies. The aetiology of

ectopic pregnancy after IVF-embryo transfer

i s

multifactorial, wi th tubal disease being the main factor. The

technique of embryo transfer may also contribute to the

increased risk of ectopic pregnancy, for example through

forcing the embryos into the tubal ostia by hydrostatic

pressure. Laparoscopic clipping

of

the proximal end of a

hydrosalpinx or salpingectomy would prevent the

occurrence of tubal pregnancies in patients with

hydrosalpinges and has, at the same time, been shown to

increase their chance of a successful outcome with IVF.*

Heterotopic pregnancy

is

estimated to occur in 1 of IVF

pregnancie~.'~

t

s

likely, however, that a significant number

are undetected in the presence of an ongoing intrauterine

gestation.

Concerning the obstetric outcome

of

assisted

reproduction,

15

the perinatal mortality rate associated wi th singleton

pregnancies is similar to that of an age-matched

the Human Fertilisation and Embryology Authority

(HFEA) prohibits the transfer o f more than two

embryos. FALSE

17 blastocyst transfer does not increase the rate of

multiple pregnancy as long as only three blastocysts

are transferred.

.................................................... FALSE

spontaneous conception control group. ............

ALSE

16

Discussion

The perinatal mortality rate in assisted reproduction

singleton pregnancies, even when matched for age, parity

and fetal sex,

is

greater than in spontaneously conceived

pregnancies. Perinatal mortali ty is increased seven-fold

50 003

Royal College

of

Obstetricians and Gynaecologists

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Answers to Questions for Volume 4, Number 3

among triplets and five-fold among twitxu Therefore,

reducing the proportion of multiple pregnancies among

IVF conceptions should contribute to a significant overall

reduction in perinatal mortal ity and morbidity. Currently, in

the

UK,

HFEA guidelines allow for the transfer of no more

than three embryos. The RCOG guidelines recommend that

no more than two embryos be transferred. In the future a

move towards transfer o f single blastocysts in women with

high reproductive potential and two blastocysts in others

should help to reduce the increase in perinatal mortality

due to multiple pregnancy.

According t o the 'Golan' classification for O S S

18 maximum ovarian diameters of >10cm may be

associated with mild OHSS.

.................................. TRUE

19 clinical ascites indicates grade 3

OHSS. ..............ALSE

20 an isolated hydrothorax does not indicate severe

disease.

................................................................. FALSE

Discussion

Table 1. Golan Classification of ovarian hyperstimulation

syndrome

Mild

Moderate

Severe

Grade 1: abdominal distension and

discomfort.

Grade 2: grade 1 plus nausea, vomiting,

and/or diarrhoea; ovaries en arged

5-12 crn.

Grade 3: features of mild

OHSS

plus

ultrasonic evidence of ascites.

Grade 4: features of moderate OHSS

plus clinical ascites and/or hydrothorax

with dyspnoea.

Grade

5:

grade 4 plus decreased blood

volume, increased blood viscosity,

hypercoagulability, diminished renal

perfusion and function.

Additional reference

i

Schenker JG, Weinstein

D

Ovarian hyperstimulation

syndrome:

a

current survey. Fertil

Steril

1978;30:255-68.

Unsafe abortion: a preventable problem

The following statements are true:

21 The induced abortion rate per 1000 women

i s

significantly higher in developed than developing

countries.

.............................................................. FALSE

22 A

rise

in contraceptive practice

is

initially associated

wi th a rise in abortion rate.

................................. TRUE

23 On average, one woman in ten wi ll have one induced

abortion before reaching the menopause.........

ALSE

Discussion

The abortion rate, per 1000 women of fertile age,

is

similar

in developed and developing countries (39 and 34

respectively). Contraceptive prevalence and induced

abortion rates sometimes rise in parallel in communities

where couples are beginning to try t o have fewer children.

Later,

as

fert i l i ty falls, high contraceptive use is associated

with lower abortion rates. On average, every woman now

entering her fertile years will have one abortion before

reaching the menopause.

Concern ng mo rta

ity

and morbidity,

24 the mortal ity associated wi th some tradit ional

abortion techniques

is

up to 500-times higher than

vacuum aspiration abortion performed by a trained

individual.

.............................................................. TRUE

25

in Africa the risk of death from induced abortion

is a t

least 500 times greater than in a developed country.

................................................................................ TRUE

26 about 13% of maternal deaths worldwide are

associated with abortion.

..................................... TRUE

27 despite restrictive laws regarding abortion in India,

malaria

st i l l

remains

a

greater cause of death than

unsafe abortion....................................................

FALSE

Discussion

The risk of death from first-trimester unsafe abortion using

traditional techniques i s up to 500 times higher than

abortion using vacuum aspiration.' The World Health

Organization estimates that, of the 515 000-585000

maternal deaths that occur across the world each year, 13%

are abortion related.gData have shown that in Africa there

are 680 deaths for every 100000 abortions whereas in

developed countries, where most abortions performed are

safe, the death rate is between 0.2-1.2 (per 100000

abortions).' In India between 15 000-25

000

women die

each year

as

a result of unsafe abortion; it

is,

therefore,

responsible for more deaths than malaria.

Regarding solutions for unsafe abortion,

28

29

30

in India safe abortion

i s

limited by the availability of

university-trained doctors

.................................... TRUE

vacuum aspiration enables most incomplete abortions

to be treated as day cases.

................................... TRUE

when post-abortion contraceptive advice was given,

the number of women using contraception in Bolivia

rose eight-fold.......................................................

TRUE

Discussion

Although India liberalised

i t s

abortion law in 1970, access

to safe abortion

is st i l l

limited as only university-trained

doctors can legally carry out abortions. Following manual

vacuum aspiration for incomplete abortion, most women

can be discharged from the hospital or clinic within a few

hours.

As part of post-abortion care, women should be

counselled and given contraceptive advice. A study on

contraceptive use before and after counselling revealed hat

in Bolivia contraceptive use before such intervention was

only 10%. Following intervention this figure rose to 88%.

Regarding manual vacuum aspiration (MVA),

31

32

33

34

Discussion

In Bangladesh abortion, or menstrual regulation,

i s

considered a legal family planning method. There

is

an

estimated 10000 individuals trained to perform MVA,

approximately half of which are doctors and the others are

health workers. MVA equipment can cost

as

little as

USS5.00, a weighted cost o f 87% less than D&C. The

equipment can be reused many times, but it is important

that the syringe is kept clean and the cannulae are

sterilised. This method can be used to perform abortions up

to a menstrual age of 12 weeks.

Concerning

the

use of rnisoprostol,

35

36

in Bangladesh approximately half of the trained MVA

practitioners are not doctors ...............................

TRUE

the equipment can be reused many times .........

RUE

this method can only be used up to

a

menstrual age

of 10 weeks.

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

FALSE

the weighted cost is more than 50% cheaper than

D&C.

....................................................................... TRUE

it

is effective as an abortifacient only when used

orally.

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

FALSE

when used as an abortifacient in countries where the

procedure remains illegal there has been no change

in the incidence of septic abortions

ALSE

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Answers t o Questions for Volume 4, Number 3

37 there have been reports of an increased risk of

ectopia vesicae (exstrophy of the bladder) following

the unsuccessful use of misoprostol. ...................TRUE

38 the American manufacturers of misoprostol do not

recommend it for use as an abortifacient...........TRUE

Discussion

Misoprostol can be used to terminate pregnancy when

used either orally or vaginally. Where women have access

to misoprostol, even in areas where abortion is illegal, the

number of hospital admissions for septic abortions

i s

falling. Misoprostol

i s

manufactured by Searle and

marketed under the tradename Cytotec , fo r the

treatment of gastric and duodenal ulcers. Misoprostol

is

not licensed for use

as

an abortifacient and the

manufactures do not support i t s use for this purpose.

There have been reports of abnormalities in children

born following the unsuccessful use of misoprostol as an

abortifacient, including ectopia vesicae (exstrophy of the

bladder), Moebius syndrome (paralysis of the facial

muscles),

I

mb defects, hyd ocephaIus and

a

rth og yposis.

Regarding the politics

of

abortion,

39

40

f i f t y percent of the world's women of reproductive

age live in countries with restrictive laws..........ALSE

overseas aid provided by Britain forbids the use of

taxpayers' money to support safe abortion.......FALSE

Discussion

There are 1.4 billion women of reproductive age in the

world, 26% of these women live in countries wi th highly

restrictive abortion laws. Only the United States permits safe

abortion inside the country while forbidding the use of

overseas aid t o help women obtain safe abortions

elsewhere.

Management of urge urinary incontinence

Urge urinary incontinence s

41 most commonly due to idiopathic detrusor

overactivi y.............................................................

TRUE

42 often associated wi th frequency and nocturia.

.TRUE

43 rarely caused by factors extrinsic to the bladder.

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

FALSE

Discussion

Urge incontinence is most frequently caused by idiopathic

detrusor overactivity but has many other potential causes.

Causes that are extrinsic to the bladder include external

pressure (e.g. pregnancy), psychosocial factors (e.g.

dementia) and iatrogenic causes (e.g. diuretics and other

drugs);

it

can also arise due to other medical conditions

(e.g. diabetes). The most common symptoms are frequency,

urgency and nocturia.

Idiopathic detrusor overactivity

44

45

46

47

i s cured by pharmacotherapeutic treatments in over

50% of cases......................................................... FALSE

can reliably be diagnosed on a history of frequency,

urgency and nocturia. ......................................... FALSE

i s

often caused by excessive fluid intake.

..........FALSE

is

usually due to intrinsic disease of the detrusor

muscle .................................................................. FALSE

Discussion

While symptoms of idiopathic detrusor overactivity can

usually be ameliorated with behavioural and pharma-

cotherapeutic treatments

it is

rarely cured. Urodynamic

assessment

is

the only way of obtaining a clear diagnosis of

the cause of urinary incontinence

as

symptomatology

is

often misleading.

Frequency of voiding is often caused by excessive fluid

intake but concentrated urine i s known to worsen the

symptoms of detrusor instability, as is excessive caffeine

intake. It i s as yet unclear whether the cause of detrusor

overactivity is myogenic or neurogenic.

Urodynamic assessment (UDA)

48

49

50

may be more accurate if ambulatory techniques are

employed.

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

TRUE

findings usually correlate well with the severity and

types of symptoms experienced......................... FALSE

is being superseded by ultrasound of the bladder in

the diagnosis of detrusor instability. .................

FALSE

Discussion

UDA

is

mandatory

if

surgery, particularly repeat surgery, for

incontinence s to be undertaken. UDA is required to make

the diagnosis of idiopathic detrusor overactivity, however,

empirical treatment of urge incontinence also has a

recognised role. Often there is no significant relationship

between the reported severity and type of symptoms and

the actual urodynamic variables. Ambulatory urodynamics

are currently only being used in the research setting but are

thought to be more physiological and perhaps more

accurate. Ultrasound evaluation of bladder wall thickness

is

useful

if

outflow obstruction

is

suspected.

In the treatment

of

idiopathic detrusor overactivity,

51

52

53

54

55

56

bladder dril l

i s

unlikely to be successful in the younger

patient.

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

FALSE

routine cystodistension does not provide good long-

term benefit. TRUE

slow release preparations have fewer side effects than

immediate release equivalents. ...........................

TRUE

anticholinergic drugs are generally well tolerated.

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

FALSE

imipramine should be used as

a

first-line treatment.

FALSE

surgery

i s

reserved for intractable symptoms.

TRUE

Discussion

Bladder drill, although requiring good motivation,

is

much

more successful in the younger patient. Alternative

therapies such as acupuncture, hypnotherapy, and

transcutaneous electrical nerve stimulation have shown

promise in the treatment of idiopathic detrusor overactivity

but have not yet been rigorously evaluated. Controlled-

release preparations of oxybutynin are just as effective as

immediate-release preparations but are associated wi th

a

lower incidence of dry mouth (68% versus 87%).

Anticholinergic drugs lack specificity for the muscarinic

receptor subtypes and as a result have an extensive adverse

effect profiles. Evidence for the value of imipramine as a

treatment

is

conflicting and, therefore, this should not be

used as a first-line treatment. Cystodistension was formerly

routinely used to treat idiopathic detrusor overactivity but

has been shown to be of l i t t le long-term benefit. More

radical surgical procedures are reserved for the most

refractory cases.

Regarding muscarinic receptors,

57 M3 receptors are found in the bladder.

..............RUE

58 M2 receptors are found in the salivary glands..FALSE

59 oxybutynin is a nonselective muscarinic receptor

antagonist.

........................................................... FALSE

60 darifenacin i s an M3 receptor antagonist.

..........

TRUE

Discussion

There are five types of muscarinic receptor within the body

(Ml-M5). The M2 and M3 receptors are found within the

bladder; M2 receptors predominate but the M3 receptor

seems to mediate he main part of bladder contraction. M3

receptors are also found in the salivary glands, the

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Answers to Questions for Volume

4,

Number 3

lachrymal glands and the bowel, which explains the adverse

effect profiles of many drug treatments for idiopathic

detrusor overactivity. Oxybutynin,

a

tertiary amine,

is

a

highly selective M1 and M3 muscarinic receptor antagonist.

Darifenacin s a highly selective M3 receptor antagonist.

Impact

of

contraception on subsequent fertility

Following cessation

of

the combined oral contraceptive

pill (COC)

61

62

63

less than 30 of women wil l ovulate in the first cycle.

.............................................................................. FALSE

there

is

an increased risk of miscarriage

...........

ALSE

women should be advised to use a barrier method of

contraception for three months before they attempt

to conceive.

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

FALSE

Discussion

The return of ovulation following cessation of the

combined oral contraceptive pill i s rapid and around 70

of women will ovulate in the first cycle. Women who

conceive immediately following cessation of the combined

pi ll can be reassured that there

is

no evidence of increased

risk of miscarriage or fetal abnormality. There

is

no

scientific evidence that women need to use an alternative

method of contraception on cessation of the combined pill

prior t o attempting t o conceive.

With regard

t o

'post-pill amenorrhoea',

64

65

66

more than 5 of women remain amenorrhoeic after

six months ............................................................ FALSE

it i s more common in women who lose weight when

using COC. ............................................................. TRUE

if

it

lasts longer than six months, then investigation is

warranted. ............................................................. TRUE

Discussion

'Post-pill amenorrhoea' affects around 1 of women six

months after stopping the combined pill.

It

may signify the

unmasking of an underlying gynaecological abnormality

such

as

polycystic ovary syndrome, hyperprolactinaemia or

a premature ovarian failure

so

these conditions should be

excluded. Loss of weight while taking the combined pill i s

associated with 'post-pill amenorrhoea' although the exact

mechanism of this is not understood.

After discontinuing depot medroxyprogesteroneacetate

67

ovulation does not return on average until after

12

months ................................................................. FALSE

68

around

90

of women will have conceived by

24

months................................................................... TRUE

69

the delay in return to fer t i l i ty is thought t o be due to

delayed metabolism of crystalline deposits.

.......

TRUE

Discussion

Ovulation returns on average four to five months following

the last injection of depot medroxyprogesterone acetate.

Although there is a small delay in the return of fertility, over

90

of women wil l have conceived by

24

months, which

i s

equivalent to women discontinuing other methods of

contraception. The delay in return of ferti lity is thought to

be due to slow metabolism of microcrystalline deposits in

muscle tissue.

E

t

onorgest eI re asing subd

e

r maI implant (Imp anon@)

70

71

72

reliably inhibits ovulation..................................... TRUE

has a Pearl Index of zero. TRUE

is

associated with an immediate return of fertility on

removal.................................................................. TRUE

Discussion

lmplanon is a highly effective method of contraception

and, a t the time of writing, there have been no

documented failures. It is the only form of contraception o

have a Pearl Index of zero. lmplanon i s associated wi th an

immediate return of fertility on removal.

Concerning intrauterine devices (IUDs),

73

a young nulliparous woman should be screened for

sexually transmitted infections prior to IUD insertion.

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

TRUE

74

they increase the likelihood of ectopic pregnancy.

.............................................................................. FALSE

75

there is a peak incidence of pelvic infection in the first

few weeks after insertion

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

TRUE

76 Levonorgestrel releasing

intrauterine system

(Mirenaq

is

associated with a higher risk of pelvic

infection than a copper IUD. .............................. FALSE

Discussion

An IUD is not associated with a significantly increased risk of

pelvic infection when used by women in monogamous

relationships wi th no risk factors for sexually transmitted

diseases. IUDs protect against all types of pregnancy,

including ectopic pregnancy. Although in the event of

failure of an IUD, the risk of ectopic pregnancy

is

higher

than in the normal population. Higher risk women such

as

young nulliparous women and those requesting a post-

coital IUD should be screened bacteriologically prior t o

insertion. There is a peak incidence of pelvic infection in the

first few weeks following insertion due to introduction of

organisms into the uterine cavity. Mirena may offer

additional protective benefit against the risk of pelvic

infection compared with copper IUDs, as a result of i ts

hormonal action.

A woman using a diaphragm and spermicide for

contraception

77

78 has an increased risk of having an infant with cleft

palate if the method fails.

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

FALSE

Discussion

Women using barrier methods of contraception have a

lower risk of pelvic infection. Although there was some

concern in the past about possible teratogenesis n women

using spermicide at the time of conception, recent scientific

data have been reassuring. There

i s

no evidence of

increased risk of congenital abnormality and use of

spermicide in the periconceptional period would not

represent grounds for therapeutic abortion.

The following statements are correct:

79 Inadvertent use of COC during early pregnancy

increases the risk of masculinsation of the female

fetus.

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

FALSE

80 There i s no evidence to support the use of routine

antibiotic prophylaxis on insertion of IUDs

........

RUE

Discussion

Inadvertent use of COC during early pregnancy does not

increase the risk of masculinsation of female fetuses,

especially with modern low-dose preparations. There is no

evidence to support the use of routine antibiotic

prophylaxis on insertion of IUDs, although preinsertion

bacteriological screening may be appropriate in some

cases.

Fetal resuscitation in labour

With regard to caesarean section,

81 when performed for a cord prolapse

it

would be

classified as a grade three procedure ................ALSE

82

regional anaesthesia compared with a general

has a reduced risk of pelvic infection..................RUE

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Answers to Questions for Volume 4, Number 3

anaesthetic

is

associated wi th improved one-minute

Apgar scores.

......................................................... TRUE

there is strong evidence that a decision to delivery

interval of 30 minutes i s a critical threshold in

intrapartum fetal hypoxia

.................................. FALSE

Discussion

A caesarean performed for

a

cord prolapse

is

a

grade

1

caesarean as there i s an immediate threat to the l i fe of the

fetus. A regional anaesthetic

is

associated with

a

reduced

incidence of postoperative morbidity in the mother and

i s

also beneficial to the fetus, as it improves one-minute

Apgar scores.M However, in certain circumstances, such

as

during a persistent fetal bradycardia, there may not be

sufficient time to

site

a regional block. Evidence concerning

the 30-minute decision to delivery interval for emergency

caesarean sections

is

lacking.

Concerning maternal oxygen therapy,

84

83

a reservoir bag attached to a Hudson mask reduces

the fraction of effective inspired oxygen (FiO,).

.............................................................................. FALSE

85

the use of prolonged prophylactic oxygen in the

second stage of labour increases arterial cord blood

pH. ........................................................................

FALSE

86 fe ta l

brain tissue oxygenation

is

increased during

fifteen minutes

of

maternal oxygen therapy .....TRUE

Discussion

A reservoir bag increases the oxygen concentration the

mother inspires, as a t the middle of normal inspiration the

flow of air can be as high as 30 Vminute, which will not be

met by the flow of oxygen alone. Therefore, the patient

will breathe in the surrounding air. When prophylactic

oxygen was used in the second stage of labour, prolonged

use was associated with a significantly lower cord blood

P H . ~However, when oxygen therapy i s used for short

phases fetal brain tissue oxygenation

is

seen to increase

when measured by near-infrared spectroscopy.6

Concerning cord prolapse,

87 distending the bladder with saline has been

successfully used as part of the management of cord

prolapse................................................................. TRUE

88 in complete cord prolapse, funic replacement and

delayed delivery has been described wi th good fetal

outcomes.

.............................................................. TRUE

89 management regimes are guided by randomised

controlled clinical trials.

...................................... FALSE

Discussion

Although the traditional management for cord prolapse s

knee-chest position and immediate caesarean, both funic

replacementz8and distending the bladder have been

described.'6 There have been no randomised controlled

trials comparing different management regimens.

Concerning maternal position in labour,

90 measurement of maternal systemic blood pressure is

useful when assessing aortocaval compression.FALSE

91

a left-lateral position compared with

a

supine

position can improve

f e ta l

oxygen saturation by over

5 . ........................................................................

TRUE

Discussion

Kinsella et a/. demonstrated that aortic compression was

relieved by increasing the amount of tilt 12 This was

measured with toe pulse pressure. However, during the

compression there was no systemic hypotension. Fetal

oxygen saturation measured by oximetry shows a significant

decrease in mean fetal oxygen saturation from

53.2

in the

left-lateral position to 46.7 the supine p0siti0n.l~

With regard t o cardiotocographic (CTG) abnormalities and

the use

of

tocolytics in labour,

92

amniotic infusion may be used in selected cases in

labour t o treat some CTG abnormalities.............

TRUE

93 magnesium sulphate

i s a

less effective tocolytic in

labour than terbutaline.

....................................... TRUE

94 intravenous glyceryl trinitrate

is

a long-acting

tocolytic.

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

FALSE

95

intravenous terbutaline reduces uterine activity by

over

75

in

15

minutes .......................................

TRUE

96 adverse effects o f terbutaline include vomiting.TRUE

Discussion

Amniotic infusion has been shown to improve CTG

abnormalities and reduce the incidence of caesarean

sections, however, in these studies, fetal distress was not

confirmed by fetal blood ~arnpli ng.~agnesium sulphate

s

significantly less effective than terbutaline a t reducing

uterine activity. Glyceryl trinitrate has a short half life;

whereas terbutaline, as well

as

effectively reducing uterine

contractions, has

a

more prolonged action.lg Terbutaline

is

fast acting and can reduce uterine activity by up to 87.3 in

15

minutes. However, it can have significant adverse effects

including maternal tachycardia, palpitations, vomiting and

tremors.

With regard t o uterine activity in labour,

97

a uterine contraction of

1

kPa causes cessation of

placental bloodflow ............................................

FALSE

98 a

contraction interval of less than

two

minutes results

in a fal l of cerebral oxygenation. ........................ TRUE

99

the effects of a rapid infusion of normal saline on

uterine activity will last for

a t

least one hour. ..FALSE

100 fifteen minutes after ceasing an oxytocin infusion

there is approximately a 20 reduction in uterine

activity. ...................................................................

TRUE

.

Discussion

Uterine contraction above 4-6 kPa causes a cessation of

maternal intervillous placental bloodflow.16This produces

a

relative fetal hypoxia; recovery takes 60-90 seconds. A

short contraction interval of

less

than

two

minutes results

in a fall of cerebral oxygenation. The effects of a rapid

infusion

last

only

last 20

minutes. Stopping an oxytocin

infusion will not cause an immediate cessation of uterine

activity. After

15

minutes there

is

only a

22

reduction in

activity, by 30 minutes a 39 reduction and by 45 minutes

a 48 reducti~n.'~

A

clinical approach to heart disease in pregnancy

Part

1:

general considerations in man agem ent

Pregnancy is contraindicated in the following cardiac

conditions:

101 Eisenmenger's syndrome. .....................................

TRUE

102 severe asymptomatic aortic stenosis. TRUE

103 previous peripartum cardiomyopathy with residual

mild lef t ventricular dysfunction

......................... TRUE

104 mitral valve prolapse with severe mitral valve

Discussion

There are some common contraindications to pregnancy,

which have been well documented. These include severe

pulmonary hypertension, either primary or secondary, of

which Eisenmenger's syndrome is associated with up to

50 maternal mortality.' Any severe obstructive lesions,

whether they are symptomatic or not, are contraindicated

to pregnancy. Severe aortic stenosis

is

associated wi th

17

maternal mortality. Any minor decrease in preload or

increase in vascular volume

i s

detrimental. Surgical

regurgitation. FALSE

54

8/18/2019 toag.5.1.50

6/7

Answers

to

Questions for Volume

4,

Number

3

management

is,

therefore, advisable before pregnancy. '

Previous peripartum cardiomyopathy

i s

another

contraindication because of the high risk of recurrence and

overall poor prognosis.iv Regurgitant valve disease

is

well

tolerated in pregnancy because the systemic vasodilatation

favours

a

forward flow with an unimpeded lef t ventricular

filling.

Regarding heart disease in pregnancy,

105 evidence confirms that antibiotic regimens during

labour reduce the frequency of endocarditis.

...FALSE

106 valvular regurgitation carries a greater risk for the

mother than valvular stenosis.............................

FALSE

107 urinary tract infection

is a

significant risk factor for

the development of heart failure.

....................... TRUE

Discussion

There

is

no evidence to suggest that prophylactic antibiotic

regimens have an effect on the frequency of endocarditis.

Valvular stenosis carries

a

moderate to high risk of

mortality

(1-1

5 ) whereas mild t o moderate valvular

regurgitation carries

a

low risk (el

%).

Risk factors for heart

failure include anaemia, hypertension, multiple pregnancy

and infections, especially urinary tract infections.

The following statements

are

correct:

108 The use of angiotensin-converting enzyme (ACE)

inhibitors i s safe during pregnancy.

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

FALSE

109 Paroxysmal nocturnal dyspnoea may be

a

normal

symptom of pregnancy....................................... FALSE

110 Cardiac output a t 24 weeks gestation is 45 greater

than in the non-pregnant state. .......................... TRUE

Discussion

ACE inhibitors should be avoided during pregnancy,

as

they are associated with

f e ta l

and neonatal renal failure

and death. While some symptoms such as palpitations can

be normal during pregnancy paroxysmal nocturnal

dyspnoea, synscope, haemoptysis and chest pain are not

and should be evaluated. Cardiac output increases in

pregnancy and by 24 weeks of gestation it rises to 45

above the baseline.

Additional references

i

Gleicher

N,

Midwall

J,

Hochberger D, Jaffin

H.

Eisenmenger's syndrome and pregnancy. Obstet

Gynecol Sun/ 1979;34:721-41.

ii Arias F Pineda J. Aortic stenosis and pregnancy. I

Reprod Med 1978;4:229-32.

iii

Oakley CM. Valvular disease in pregnancy.

Curr

Opin

Cardiol 1996;11:155-9.

iv. DeMarkis

JG,

Rahimtoola

SH.

Peripartum cardiomyo-

pathy. Circulation

1971;44:964-8.

v. Tang

LCH,

Chan S Y W Wong VCW, Ma HK. Pregnancy in

patients with mitral valve prolapse. lnt I Gynaecol

Obstet 1985;23:217-21.

Inte rpret ing statistics with confidence

A

95 confidence interval for the mean estimated from a

large random sample of observations

is

a set of values within which, in the long run, 95

of observations fall.

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

FALSE

112

i s a

way of measuring the precision of the estimate of

the mean TRUE

113

is

an interval within which the sample mean falls with

probability 0.95................................................... FALSE

114 i s chosen so that 95 of such intervals will include the

population mean ..................................................

TRUE

115 can be calculated from mean minus 1.96 standard

errors to mean plus 1.96standard errors............

RUE

Discussion

The confidence interval for the mean does not te l l us

anything about the distribution or variability of the

observations. The sample mean

i s

always in the middle of

the limits. In large samples, sample estimate k1.96 tandard

errors

is

the usual way of calculating confidence intervals.

A

study

of

maternal depression was carried out in

Victoria,

Australia, in September 1993. he point

prevalence of depressiona t six t o seven months

postpartum was 16.9 (22511331; 5 C I 14.9 o 18.9 ).'

116 Another sample of the same

size

from this population

would have shown a rate of depression between

14.9 and 18.9

................................................. FALSE

117 95 of such women have a probability of between

14.9 and 18.9 of reporting depression........FALSE

118

It

is likely that between 14.9 and 18.9 of women

in the area would report depression

a t s ix

to seven

months postpartum.

............................................. TRUE

119 If the sample were increased to 2662 mothers, the

95

confidence interval would be narrower.

....TRUE

120

It

would be impossible o get these data if the rate for

all mothers in South Australia was

14 .

...........

FALSE

Discussion

The confidence interval i s an estimate of the overall

proportion, which applies to all women. It is the probability

that a woman chosena t random will have depression. We are

not estimating the distribution of risk. Ninety-five percent of

possible samples will have confidence intervals that contain

the population proportion, but this particular confidence

interval will not include95 of possible sample proportions.

A larger sample would result in a reduced standard error and

a narrower interval. A population proportion outside the

confidence interval

is

not impossible, as

5

of confidence

intervals do not include he population value.

In

a

randomised tr ial

of

vaginal clindamycin versus

placebo for early pregnancy bacterial vaginosis, the odds

ratio of preterm birth was

2 5

(95yo

C I

0.6

o

10.O).z

121 The odds ratio would be zero if the two treatments

had the same effect

............................................. FALSE

122 The treatments are not significantly different a t the

5

level. ................................................................ TRUE

Discussion

The odds ratio would be 1

O if

the treatment had no effect.

An odds ratio of zero would indicate

a

very large effect. As

the 95 confidence interval includes 1.0, he data are

consistent with the null hypothesis and the difference

is

not

significant.

In

a

trial of prednisolone versus placebo in children with

acute asthma, 2 of the

73

patients in the placebo group

were discharged

a t

first examination (3 ; 95

CI

1 t o

6 ).)Reported by Altn~an.~

123 This confidence interval i s plausible. FALSE

124 The exact binomial method should have been used

here........................................................................

TRUE

Discussion

The confidence interval should not include a negative

number, because the number of children discharged cannot

be negative. The large sample normal approximation t o the

binomial distribution has been used, but the sample is too

small. The exact binomial method would be much better,

giving 0.3 to 9.5 .

Children born during tw o randomised controlled trials of

routine ultrasound screening during pregnancy were

followed up

a t

ages eight to nine ears.A sample of

children underwent specific tes ts or dyslexia. The

t es t

55

8/18/2019 toag.5.1.50

7/7

Answers to Questions

for

Volume

4,

Number 3

results classified 21

of

the 309 screened children (7 ;

95

C I

3

o

10 )

and

26

of the

294

controls

(9 ; 95 C I

4

o

12 )

as dyslexic.'

125

A confidence interval for the difference between the

percentages would be more useful than those given.

................................................................................ TRUE

126 A confidence interval for the ratio of the percentages

would be more useful than those given.

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

RUE

Discussion

Confidence intervals are always calculated regarding the

data as a sample. A sample of a sample is still a sample.

Much more useful would be

a

confidence interval which

compares the two groups directly. For the difference

between prevalences

it

would be 6.3 o +2.2 percentage

points, for the ratio

it

would be

0.44

o 1.34.

In a study of mitomycin in the treatment of non-small-cell

lung cancer, subjective response was reported complete in

two of 20 patients, reported as 10 ; 95 C I 0 o 21.6

127 The confidence interval should not include zero.

................................................................................ TRUE

Discussion

As we have observed a complete response in two patients,

it

i s impossible for the proportion in the population of

patients that includes them t o be zero.

Danish women having undergone h sterectomy with

from 1977 o 1981 (n

=

22 135)were compared with all

Danish women who had not undergone hysterectomy. The

extrapolated lifetime risk of developing ovarian cancer

was 2.1 after hysterectomy and 2.7 in the general

population

RR

0.78; 5

C I

0.60 o 0.96).'

128 If there were no difference, the expected relative risk

would be 1.0......................................................... TRUE

129

The difference

i s

statistically significant

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

TRUE

Discussion

The null hypothesis value for a ratio is usually 1.0.As the

confidence interval does not include this, the difference

is

significant a t the 0.05 evel.

Salpingectomy and conservative tuba1 surgery as

treatments for ectopic pregnancy were compared

economically In the short term, costs per patient were

f1,554 (95 C I f1,501 o f1.656) or salpingectomy and

f1,787 (95 C I f1,683 o f1,930)or conservative

surgery.8

130 The different in cost between the two regimens is

statistically significant...........................................

TRUE

Discussion

The 95 confidence intervals do not overlap,

so

the

difference

i s

statistically significant. The authors also

correctly presented an estimate and confidence interval for

the difference in mean cost, f233 (95 CI f80 o 371).

conservation of a t least one ovary or a benign indication

The Obstetrician & Gynaecologist

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Obsferricinn G C y m e d q i s r

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For reference citations to these answers, please refer to

those in the original questions, not those in the article (The

Obstetrician iynaecologist2002;4: 50)

Greentop Guideline 30: Managem ent

of

genital

herpes in pregnancy

The following statements are correct:

131

Most maternal herpes simplex virus (HSV) infections

are asymptomatic.................................................. TRUE

132 Lower segment caesarean section (LSCS) is

recommended for

al l

women presenting with

first-

episode genital herpes lesions during the second

trimester. .............................................................. FALSE

133

Antenatal swabbing accurately predicts the shedding

of virus a t the onset of labour ........................... FALSE

134 Almost all cases of neonatal herpes occur

as

a result of

postnatal transmission ........................................ FALSE

135 The incidence of neonatal herpes is less than two per

100000 live births annually in the

UK

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

TRUE

136 Serological testing for HSV in late pregnancy i s cost

effective in preventing herpes related morbidity.

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

FALSE

137 There i s no clinical evidence of fetal toxicity when

aciclovir i s administered t o the mother in late

pregnancy.

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

TRUE

138 Obtaining a history of genital herpes in the partner of

a woman i s not an accurate way of determining the

risk of acquiring primary HSV infection during

pregnancy. TRUE

139 Where genital herpes is present for the first time a t

the time of delivery, the risk of transmission to the

fetus

i s

dependant upon the time that the

membranes have been ruptured. ........................

TRUE

140

Routine performance of

LSCS

in cases of maternal

recurrent genital herpes lesions has led t o a

significant decline in the incidence of neonatal

herpes.

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

FALSE

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for

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56