back to basics! the essence of obstetrics in two hours susan aubin, md, frcsc assistant professor...
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Back to Basics!
The essence ofOBSTETRICSin two hours
Susan Aubin, MD, FRCSCAssistant ProfessorDepartment of Ob/GynThe Ottawa Hospital/University of Ottawa
Special Thanks to:Karine J. Lortie , MD, FRCSC
OVERVIEW
•Introduction•Early pregnancy•Antenatal care•Teratogens •Fetal growth and wellbeing•Medical complications•Breech•Multiple pregnancy •Labour
INTRODUCTION
RISK SPECTRUM IN PREGNANCY
LOW RISK (75%): normal obstetrics
MEDIUM RISK (20%): pre-post dates breech
twins maternal age, etc..
HIGH RISK (5%): genetic disease serious obstetric maternal complications
RISK IN PREGNANCY
Definition of Outcome Measures
1.Perinatal mortality rate• all stillbirths (intrauterine deaths) > 500 grams plus
all neonatal deaths per 1,000 total births2.Neonatal death
• death of a live-born infant less than • 7 days after birth (early) or less than 28 days (late)
3.Live birth• an infant weighing 500 grams or more exhibiting any
sign of life after full expulsion, whether or not the cord has been cut and whether or not the placenta is still in place
PERINATAL MORTALITY RATE
•ONTARIO: 5/1000
•Developing: 100/1000
PERINATAL MORTALITY
•Prematurity•Congenital anomaly•Sepsis•Abruption•Placental insuffienciency•Unexplained stillbirth•Birth asphyxia•Cord accident•Other ie. isoimmunization
MATERNAL MORTALITY RATE
•ONTARIO: 5/100 000
•Developing: 1000/100 000
MATERNAL MORTALITY
•Direct Deaths•Indirect deaths: < 42 days from delivery
Causes:•Hypertensive disorders•Pulmonary embolism•Anesthesia•Ectopic pregnancy•Amniotic fluid embolus•Hemorrhage•Sepsis
EARLY PREGNANCY
EARLY PREGNANCY
Dating:40 weeks from LMP280 days, Naegle’s rule (-3 months + 7 days)Affected by cycle lengthHegar’s sign: soft uterusChadwicks sign: blue cervix
8 days 8 weeks 16 weeks
5,000
Level
100,000
doubling time 2 days
Others use:Zone 2000-6000
•Mole•Ectopic•Ovarian cysts
Hormones
BhCG:A subunit similar to TSH, LH, FSHMeasurable 8 days post conceptionRole: stimulate CL progesterone
Other placental hormones
HPL = human placental lactogen (growth hormone)prolactinprogesteroneestrogen
ANTENATAL CARE
Maternal physiologyRBCplasma volume by 50%, GFR, CrCl (creatinine), glucosuriacardiac output (highest 1st hour after delivery)HR by 20%SVPlacental flow: 750ml/min at term
Antenatal careAntepartum history:age: >40 offer amniocentesisParity/gravidityMedical, surgical historyFamily, social historyMeds, allergies
Routine tests:CBC (Hg), Type and Screen, prenatal antibodiesVDRL, Rubella, Hep B, HIVUrine culturePap smear, + vag swabs, cervical culturesOffer IPSGBS swab at 35 weeks
Antenatal CareOther testing:Dating ultrasound, 18 weeks morphology ultrasoundHb electrophoresis (Thalassemia, sickle cell, etc.)Chicken pox, parvovirus, TSH28 weeks glucose screening testGenetic testing:CVSAmniocentesisScheduled visits:0-28 weeks: q4 weeks28-36 weeks: q2 weeks36+ weeks: q1 week
Scheduled visitsSFH (cm): (+ 2 # of weeks)Sensitivity of 60%12 weeks: symphysis pubis20 weeks: umbilicus36 weeks: siphisternumpresentationSymptoms, fetal movement+ urine dip: glucose, proteinBlood pressure, maternal weight
MATERNAL WEIGHT
wks gain
0 - 20 4 kg21 - 28 4 kg29 - 40 4 kgAverage 12 kg
•Weight Gain: •Underweight: 35-45 lbs (15-20 kg) •Normal BMI: 25-35 lbs (11-15 kg)•Overweight: less than 25 lbs (10 kg)
Genetic testing
IPS:First Trimester screening (10.6 – 13.6 weeks)
Nuchal translucency PAPP-A, (BhCG)
Second Trimester screening (15-16 weeks) BhCG, estriol, AFP, Inhibin A
87% detection rate, 2% false positive rate
MSS: (Quad test)15-19 weeksBhCG, estriol, AFP, Inhibin A77% detection rate, 5% false positive rate
IPS vs MSS Detection rate
NT
Suchet I, Tam W. The ultrasound of life. Interactive fetal ultrasound teaching program on DVD, 4th Edition, 2004.
Screening patterns
Down’s syndrome: low PAPP-A, AFP, estriol, high BhCG
Trisomy 18: low PAPP-A, AFP, BhCG, estriol, Inhibin A, high NT
Trisomy 13: high AFP, low BhCG/estriol
NTD: high AFP
Low estriol – associated with many congenital anomalies
Which of the following statements best describes the foramen ovale:
It shunts blood from right to left
It connects the pulmonary artery with the aorta
It shunts deoxygenated blood into the left atrium
It is an extra cardiac shunt
It is functional after birth
TERATOGENS
Risk Classification System for Drug Use in Pregnancy
Category Description
A Taken by a large number of pregnant women. No increase in malformation.
B Taken by only a limited number of pregnant women and women of childbearing age. No increase in malformation. Studies in animals wither show no increase or are inadequate. C Have caused or may be suspected of causing harmful effects on the human foetus or neonate without causing malformations. These effects may be reversible.
D Have caused an increased incidence of human foetal malformations or irreversible damage.
X Drugs that have such a high risk of causing permanent damage to the foetus that they should not be used in pregnancy.
FETAL GROWTH AND WELL-BEING
Dating Scan
Gestational sac: 5wksFetal pole: 6wksFetal heart: 7 wksLimb buds: 8 wks crown rump length
Morphology scan
18- 20 weeksBPDHCACFemur length
Info from U/S
•Estimated fetal weight
•Twins discordance
•Behavioral states (BPP)
•Presentation
•Placenta (previa)
Anomalies: ultrasound 18 - 20 weeks
•Spina Bifida•Anencephaly•Cardiac•Renal•Diaphragmatic hernia•Limbs •Facial•Chromosomal
Late > 20 weeks
•Renal•Microcephaly•Hydrocephalus•Ureteral valves
Interventions•amniocentesis, l/s ratio (lung maturity)
•cvs
•cordocentesis, transfusion
•paracentesis
•Shunts: bladder, ascites, kidney, head
•Liver biopsy, skin
•Fetal reduction
DEFINITION OF I.U.G.R
•< than 2500 grams•< than 5th centile for GA•Approx. 4-7% of infants
BPD
AC
BPD
AC
CAUSES OF IUGR
•Maternal: Malnutrition Drugs Substance Abuse Diseases Infections
•Fetal: Chromosomal Abnormality Congenital Abnormality Multiple Gestation Congenital Infection
CAUSES OF IUGRPlacental:PerfusionAbnormalities:
Abnormal Cord Insertion Abruption Circumvallate placentation Placental Hemangioma Placental Infections Twin to Twin Transfusion
IMMEDIATE NEONATAL MORBIDITY IN IUGR
•Birth asphyxia•Meconium aspiration•Hypoglycemia•Hypocalcemia•Hypothermia•Polycythemia, hyperviscosity•Thrombocytopenia•Pulmonary hemorrhage•Malformations•Sepsis
CAUSES OF FETAL OVERGROWTH
•Maternal diabetes
•Maternal obesity
•Excessive maternal weight gain
EVALUATION OF WELL-BEING
FETAL ACTIVITY
•Kick counts:• “count to ten “ chart• towards term• 10 movements in 2 hours over 12 hours
BIOPHYSICAL PROFILE•Graded (0 or 2 pts; max 10)
• NST (normal)• Movement (2)• Tone (2)• AFI (amniotic fluid volume)• Breathing (30 seconds)
DOPPLER•What is it?
• Uteroplacental waveforms• Umbilical artery• Carotid artery• Descending aorta
CARDIOTOCOGRAPHYMaybe as good as BPP
1.Non-stress test: movement
uterine activity
2. Stress tests:Oxytocin infusion
nipple stimulation
Features of the normal CTG:• rate 110-160 bpm• BTB variation 5-15 bpm• Accelerations present (2)• No decelerations (early, variable, late)
Which fetus to assess?
Small for gestational age, postdatesMaternal hypertension, diabetesAntepartum hemorrhage Decreased FMThe “high risk” pregnancyEtc…
WHY FETAL ASSESSMENT?
1.To prevent damage (asphyxia)
2. To deter unnecessary intervention (prematurity,operative deliveries)
WHAT IS IT LOOKING FOR?
•Fetal hypoxia before asphyxia• Signs of placental failure:• Poor fetal growth• Decr. FM• Decr. AFI• Atypical, abnormal NST
•How to test?• Fetal scalp pH sampling• Normal >7.25• Borderline >7.21-7.25 (repeat sampling in ½ hour)• Abnormal <7.20 (deliver)
Criterias for asphyxia (hypoxic acidemia)
• umbilical cord arterial pH < 7.0
• base deficit > 16
• Apgar score 0-3 for >5 minutes
• neonatal neurologic sequelae (e.g. seizures, hypotonia, coma)
• evidence of multiorgan system dysfunction in the immediate
neonatal period
NORMAL TRACE
Early decels
Late Decels
Variable Decels
Reduced Variability
Tachycardia
MEDICAL COMPLICATIONS
NAUSEA AND VOMITING
•Morning sickness: 50%•Hyperemesis gravidarum: 1%
• Tx: • Diclectin (10 mg doxylamine succinate with vit B6)• Rest• Avoid triggers• Admit if severe (i.e. dehydration, electrolytes
imbalance)• TSH, LFT• IV• Dietitian consult• Psychology
DIABETES
Incidence: 1%GDM: 3-5%Screening: 50g GTT
If > 7.8 do 75 g 2 hr OGTT > 10.3 GDM
Risks factors:Previous stillbirthPrevious LGAFHxPersistent glycosuria
ORAL GLUCOSE TOLERANCE TEST (OGTT)
Criteria (ADA):•Fasting > 5.3•1 hour > 10.0•2 hour > 8.6
• 2 of the 3 values met or exceeded = GDM• 1 of the values failed = impaired glucose tolerance
Risks:•Anomalies•Infection•Pre-eclampsia•Macrosomia•Polyhydramnios•IUFD•shoulder dystocia
Rhesus isoimmunizationIncidence:
7% african-american13% caucasionIgG anti-D in Rh –ve sensitized women
Can cause:fetal anemiaheart failureHydrops fetalisBorn with jaundiceIn-Utero Dx: Amniocentesis, Cordo, DopplerProphylaxis: WinRho @ 28 wks + postpartum (newborn Rh status)
Antepartum hemorrage (>20 wks)
Causes:Placental abruption: concealed, revealed
Signs: vaginal bleeding, pain, fetal distress Causes:
PIH (DIC) Cocaine SLE Smoking Trauma Previous abruption
Abnormal placentation: previa, vasa previa Signs: painless vaginal bleeding
PPHCauses (4T):1.Uterine aTony:
• Twins• long labor• Etc…
2.Tissue (Retained products)• Infection
3.Trauma (tears)4.Thrombin:
• Congenital Disorders• APH
PPH Treatment
Conservative:Deliver the placentalBimanual compressionUterine packingIV, xmatch, blood bank (PRBC, FFP, …)
Medical:ErgotHemabateOxytocincytotec
PPH Treatment
Surgical: Repair the tear D&C (explore the uterus) Ligate internal iliacs UAE B-Lynch suture Backri balloon Hysterectomy
HYPERTENSION
HYPERTENSION IN PREGNANCY
•Leading cause of maternal death and perinatal mortality/morbidity
•BP monitoring is major activity of antenatal care
•Affects up to 10 % of all pregnancies
TERMINOLOGY
ABNORMAL VALUES? (depends on who…)•>140 / 90•DBP > 90 two readings•Systolic rise >30 or diastolic >15
PROTEINURIA>0.3 g/day (mild); >5 g/day (severe)
Gestational Hypertension with preeclampsia with comorbid conditions
Pre-existing Hypertensionwith preeclampsiawith comorbid conditions
Classification (it changes all the time…)
Eclampsia: Convulsion during pregnancy or within 7 days to 6 weeks of deliveryNot caused by epilepsy
Risk factorsPrimigravida or new partnerAge, raceLow social classFamilial trend ?single geneUnderlying hypertensive disorder 20 %diabetes 50 %Twins (mono) 30 %Hydatidiform molePrevious gestational hypertension 30 %
Severe:
• DBP> 110 with proteinuria (3-5g/d)• Symptoms:• Headache• Scotomas• Epigastric pain/RUQ• Vomiting• Hyperreflexia
Management
MILD: monitor, deliver near term
SEVERE: stabilize and deliver
MOTHER: • Labwork: CBC, LFT, uric acid, BUN, Cr,
Albumin/creatinine ratio or 24 hour urine total protein, LDH, INR/PTT
• Symptoms: IV, meds, ….
BABY :• BPP• Ultrasound: growth, doppler• NST• Celestone, …
ANTIHYPERTENSIVES
•Short or long-term:• Methyl dopa• Labetolol• Nifedipine
•Acute:• Labetolol• Nifedipine• Hydralazine
ANTICONVULSANTS•Prophylaxis and treatment:
• Magnesium sulphate
ECLAMPSIA
•Rx:• Control airway• Stop convulsion• reduce BP• MgSO4• Deliver (C. Section?)• watch post natally
BREECH
ETIOLOGY OF BREECH PRESENTATION
•prematurity•Fetal abnormality•Multiple pregnancy•polyhydramnios•Placenta previa•Uterine abnormality
TYPES OF BREECH PRESENTATION
Extended (frank)
Flexed (complete)
incomplete
footling
MANAGEMENT OF BREECH PRESENTATION
•If diagnosed >34 weeks, options:• External cephalic version• Trial of labor with vaginal delivery• caesarean
Criteria for TOL:•At 37 - 38 weeks:
• Estimated fetal weight 2.5-4 kg• Frank or complete breech presentation• clinical pelvimetry adequate• Fetal abnormality excluded• No serious medical or obstetric complications
TRANSVERSE LIE
•Incidence: 1:200 at term•Risk factors:
• Multigravidae• Placental previa• Fibroids• Polyhydramnios• Multiple pregnancy• Contracted pelvis• Fetal abnormality• Uterine abnormality
•Management:• Ultrasound• Cesarean if doesn’t turn
MULTIPLE PREGNANCY
Twins
•Incidence:• 1:80 (triplets 1:802)• 1:320 MZ twins worldwide
•superfecundation•superfetation
•Etiology: Population based Age Parity Previous binovular twins Heredity
TwinsDiagnosis:LGAu/s: lambda signIncreased AFP
Management:RestSerial u/sAssess presentation+ IOL @ 38 wks
Placentation
Dizygotic:Separate amnion and chorionSeparate placentas
Presentation:Vx/Vx: 45%Vx/BR: 25%Br/Vx: 10%Br/Br: 10%Etc…..
Placentation
DIZYGOTIC DAY
23 % 0 - 3 Totally separate
75 % 4 - 7 Separate fetuses & amnionsingle chorion with vascularconnections
1% 7 - 11 Monoamniotic & monochorionic
1% 11+ conjoined twins
Hazards of multiple pregnancy
•Increased risk pre-eclampsia (X3)•pressure symptoms•anemia
•Abortion (disappearing sac)•Prematurity (approx. 30% deliver < 37/40 )•Polyhydramnios•twin-twin transfusion•Placenta previa•APH/PPH•Malpresentation•cord entanglement
LABOR
What is Labor ?
(: work)
Regular painful uterine contractions
accompanied by progressive effacement and
dilatation of the cervix.
Timing of Labor
40 weeks
8% deliver on E.D.C.
7% premature <37 weeks
10% post-mature >42 weeks
Signs of Onset of Labour
•“Show”•Rupture of membranes•Contractions
Detection of ruptured membranes
•Nitrazine Test:• Alkaline pH of fluid turns blue
•Ferning:• High Na+ content causes “ferning” on air
dried slide
Ferning
Cord prolapseOnly with ruptured membranesIncidence: 1/300Risk factors:80% happen in multigravidaMalpresentation:
Transverse lie Breech High head
TwinsPrematurityOB interference: forcep, arm
Cord prolapse•Diagnosis:
• Ultrasound• Pelvic exam in labour (e.g. after ROM)• FHR abnormality
•Treatment:• Don’t panic• Push up presenting part• Sims position or knee/chest• Cesarean (forceps if fully)
Stages of Labor
1st stage: Onset to ‘full dilatationLatent and active
2nd stage: Full dilatation to delivery of baby
3rd stage: Delivery of placenta
4th stage: Placenta to 6 wks PP
Table 30-1. Characteristics of Labor Nulliparas and Multiparas*
Characteristic All patients Ideal Labor All patients Ideal laborNulliparas Multiparas
Duration of first stage(hr)Latent phase 6.4(±5.1) 6.1 (±4.0)4.8 (±4.9)4.5 (±4.2)Active phase 4.6(±3.6) 3.4(±1.5) 2.4(±2.2) 2.1 (±2.0)Total 11.0(±8.7) 9.5(±5.5) 7.2(±7.1) 6.6(±6.2)
Maximum rate of descent (cm/hr) 3.3(±2.3) 3.6(±1.9) 6.6(±4.0) 7.0(±3.2)Duration of secondstage (hr) 1.1(±0.8) 0.76(±0.5) 0.39(±0.3) 0.32(±0.3)
* All values given are ± SD.
(Data from Friedman EA: Labor: Clinical Evaluation and Management. 2nd ed. New York, Appleton-Century-Crofts, 1978).
Cesarean SectionIndications
Failure to progress (Dystocia)Repeat (Failed VBAC)Fetal DistressBreech PresentationPlacenta PreviaCord prolapseAbruptionDiabetesFetal Reasons (e.g. prevent infection)Social...
Premature labor
Incidence: 7% <37 wksMajor cause of perinatal morbidityOverall recurrence risk of 30%Risk factors:Previous PTDSmokingLow incomeCervical surgeryUterine anomalyMultiple pregnancy
Premature labor
Treatment:RestSteroids (for fetal lung maturity)Tocolytics?PPROM:
Mercer protocol (IV/PO ampicillin(amoxil)/erythromycin)
Prevention:Ultrasound cervical length?Fetal fibronectin (predictor?)
Amniotic Fluid•Mainly fetal urine•Some from extraplacental membranes
• 12 wks: 50 mls• 24 wks: 500 mls• 36 wks: 1,000 mls
•Oligohydramnios:• Reduced AFI on u/s: <5cm • SFH: small for dates; baby easy to feel• Causes: • Placental insufficiency• Urinary tract dysplasia• Diagnosis:• Ultrasound• Treatment:• Intensive monitoring• Early delivery
Polyhydramnios•Definition:
• An excess of liquor to such a degree that it is likely to influence the course or management of pregnancy.
• >20 cm
•Diagnosis:• SFH increased: large for dates• Tense and uncomfortable• Fluid thrill• Difficult to feel fetus
Polyhydramnios: EtiologyMaternal:
MultipDiabetesGHTNInfection: toxoplasmosis, CMVFetal:MacrosomiaAnencephaly, hydrocephalyGut atresiaMultiple pregnancyCAN’T SWALLOW (diaphragmatic hernia, mediastinal tumor)HYDROPS FETALIS (Rh incompatibility, infection, heart disease, thalassemia major, etc.)
Dystocia
Definition:Abnormal progression of labour in the ACTIVE Phase
Cervical dilatation of <0.5 cm/hr over a 4 hr period
arrest of progress in the ACTIVE phase either in the first or second stage of labour
Failure of descent of presenting partFriedman’s curve
CAUSES OF DYSTOCIA
Power Uncoordinated uterine action Dysfunctional Labour
Passenger Cephalo-pelvic disproportionRelative disproportionMassive baby! (macrosomia)
Passages Diameters (pelvic anatomy)
Dystocia
Risk Factors:ageParityInfectionEpiduralPosition in laborInductionMacrosomiacervix
Initial measure to treat dystocia
Comfortwellbeinghydration
B. AmniotomyC. Oxytocin if A+B failD. Wait long enough to see a response
A. Attention to:
Oxytocin usage
•Dosage:• Depends on your hospital protocol• Initial dose: 1 to 2 mu/min• Rate increased by 1 to 2 mu/min every 30 min
until contractions are considered adequateand cervical dilatation achieved
• Clinical response usually seen at dose levels of 8-10 mu/min
Reduction of risk of dystocia
Avoid induction for large fetal weightAvoid oxytocin use with unfavourable cervixAvoid admission to Labour and Delivery at <4cm dilatation“Management” of epidural at full dilatationAvoid immediate pushing after full dilatation
Supportive strategies
Cervical evaluation for ripening prior to booking inductionObstetrical triageContinuous professional support in active labourMobilization of women in active labourMinimization of motor blockage with epiduralUse of amniotomy and oxytocin prior to C/S for dystocia
Cesarean section for dystocia
Timing of procedure RateLatent phase 41%Active phase 38%Second stage 21%
Source: Stewart CMAJ 1990:142; 459-463
The perinatal mortality rate is defined as:
a)The number of neonatal deaths that occur per 1000 live births
b)The number of stillbirths that occur per 1000 births
c)The number of fetal deaths within the first week after birth
d)The number of stillbirths and neonatal deaths in the first week of life per 1000 live births
All of the following factors are associated with an increased risk of perinatal morbidity except:
a) low socioeconomic status
b) low maternal age
c) heavy cigarette smoking
d) alcohol abuse
e) exercise
Appropriate management for slow labour (dystocia) associated with an occiput posterior presentation during the first ACTIVE stage of labour would include:
a) immediate cesarean section
b) forceps
c) augmentation with oxytocin
d) external cephalic version
e) fetal blood sampling
Appropriate screening tests in an early, uncomplicated pregnancy include all of the following except:
a) repeat BhCGb) hemoglobinc) syphilis serologyd) Cervical cytologye) Blood type and Rh factor
Characteristics or associated findings with late decelerations include all of the following except:
a)They may be seen in patients with pre-eclampsia
b)They may be associated with respiratory alkalosis
c)They are associated with a decreased uteroplacental blood flow
d)They often are accompanied by decreased PO2
e)They usually are accompanied by an increased PCO2
A complete breech presentation is best described by which of the following statements:
The legs and thighs of the fetus are flexed.
The legs are extended and the thighs are flexed.
The arms, legs, and thighs are completely flexed.
The legs and thighs are extended.
None of the above