OB for Studs

OBSTETRICS

■ Embryology :
* Post-conception week 1 : Implantation of blastocyst
 Intra-tubal phase : first half of the week 1

 Intra-uterine phase : entery of the morula into the uterus
Morula differentiate into a hollow ball of cells
Outer layer – trophoblast (Placenta)
Inner layer – embryo
* Post-conception week 2 : Development of the bilaminar germ disk with epiblast and hypoblast layer

 Invasion of maternal sinusoids by syncytiotrophoblast (β-HCG test becomes positive)

* Post-conception week 3 : Migration of cells through the primitive streak between the epiblast and hypoblast to form the trilaminar germ disk with ectoderm, mesoderm
and endoderm layers

* Post-conception week 4-9 : Organs & organ systems development

 Chorionic villous sampling (CVS) : fetal Karyotyping (9-12 weeks)

 Amniocentesis : genetic purpose (15-20 weeks), Rh-isoimmunization (after 24
weeks), fetal maturity (after 34 weeks)

 Percutaneous Umbilical blood sampling : fetal Karyotyping, IgM antibody detection, blood typing, intra-uterine blood transfusion (after 20 weeks)

 Placental Hormones : β-HCG, Human Placental Lactogen (HPL)

 Progesterone sources : corpus luteum of pregnancy (6-7 weeks), corpus luteum & placenta (7-9 weeks), Placenta (after 9 weeks)

 Estrogen sources : Estradiol (non-pregnant reproductive period): follicular granulosa cells; Estriol (during pregnancy): DHEA-S from fetal adrenal gland convert into Estriol by placental sulfatase; Estrone (menopause): peripheral
adipose tissues

 Steroid binding globulins increase during pregnancy, so total hormone level increase but free hormone level remains unchanged (same thing happens in person on anabolic steroids, OCP) therefore hypothyroid patient should increase dose of
thyroxine.

 Braxton-Hicks Contraction: painless, low intensity, long duration contraction (during 2nd trimester)

 Maternal Serum AFP (MS-AFP): [0.85 – 2.5 MoM]
Elevated MS-AFP – obstetric US to confirm gestational date (1st step)

Low MS-AFP – obstetric US to confirm gestational date (1st step)

 Triple marker screen: MS-AFP, hCG & Estriol (15-20 weeks)
↓↓ MS-AFP & Estriol, ↑ hCG – trisomy-21 – next step? – Amniocentesis for Karyotyping
↓↓↓ All three – trisomy-18 – next step? – Amniocentesis for Karyotyping

 Gestational Diabetes Screen – b/w 24-28 wks – 1-hr 50g oral GTT (screening test) – If level >140 mg/dl, do definitive test (3-hrs 100g oral GTT done after

 c/o ↓ fetal movement, no fetal heart tone on Doppler, next step? ultrasonography

 c/o ↓ fetal movement, fetal heart tone heard on Doppler, next step? Non-stress test

 Ultrasonography (Biophysical profile) – FHR (without any stressor like oxytocin), fetal body movement, tone, breathing, amniotic fluid index

 c/o decrease fetal movement, next step? – NST (non-stress test)

■ Perinatal Infections :

 Group B beta-hemolytic streptococci (GBBS): candidates for intra-partum
Penicillin G prophylaxis – positive GBBS urine culture, previous baby with GBBS sepsis, positive 3rd semester vaginal culture, preterm gestation, maternal fever, membrane rupture > 18 hrs

Reactive Non-reactive
Reassuring
> 10 beats / min (< 32 weeks)
> 15 beats / min (> 32 weeks)
Two acceleration in 20 mins
Next step?
Vibroacoustic Stimulation
Still non-reactive,
next step?
Biophysical Profile (US)
4-6
Perform CST
8-10
Highly reassuring
0-2
Prompt delivery
Negative
Highly reassuring
Positive (late deceleration)
Worrisome (deliver if >36 weeks)
108
 Toxoplasmosis: 3rd trimester primary infection with T.gondi – high risk of vertical
transmission
 Cesarean section: genital HSV lesions & HIV positive patients [Condylomata
acuminata is a manifestation of HPV infection and it is not a C/I for vaginal delivery]
■ Important Pregnancy changes: Increase – plasma volume, RBC mass (less
compare to plasma), factors 7,8,9,10, cardiac output, tidal volume, renal blood
flow, GFR, pituitary & thyroid gland size
 Respiratory alkalosis occur during pregnancy
 ↓ Renal glucose threshold
 ↓ gastric & bowel motility
* Herpes Gestationis: autoimmune (not due to virus) – rash and vesicles around
umbilicus in second / third trimester, recur during subsequent pregnancy – Tx:
topical triamcinolone
* Pruritic urticarial papules and plaques of pregnancy (PUPPP): it typically develops
on the abdomen, especially with periumbilical striae distensae, while the
umbilicus is usually spared (contrast to Herpes Gestationis)

Pregnancy Bleeding
Who is compromising?
Mother (low BP, shock) Fetus (bradycardia)
Vasa Previa
Next step?
Emergency C-section
Next step?
Stabilize mother
(IV line with large bore needle)
Important causes
Abruptio Placenta
Painful vaginal bleeding
h/o cocaine abuse, h/o trauma
increase fundal heights,
abnormal shape (in conceal
bleeding)
Management depends upon
Maternal or fetal jeopardy,
fetal maturity
Complications: DIC, shock
with ATN (acute tubular
necrosis)
D/D: Abruptio placenta &
Uterine rupture can be
difficult to distinguish when
present with h/o trauma, but
culdocentesis suggestive of
hemoperitoneum is seen in
uterine rupture and helpful in
diagnosis
Placenta Previa
Painless vaginal bleeding
Management depends upon
Maternal or fetal jeopardy, fetal
maturity
Complications: Shock with
ATN, Sheehan’s Syndrome
Never perform a digital or
speculum examination until
US rules out placenta previa
Placenta accreta
Placenta invades the
myometrium, but does not
penetrate the entire thickness of
the muscle.
Placenta increta
Occurs when the placenta further
extends into the myometrium
Placenta percreta
The worst form of the condition,
The placenta penetrates the
entire myometrium to the
uterine serosa (invades through
entire uterine wall)

Complete Abortion : All products of conception passed, US show no intrauterine contents

■ Rh-Isoimmunization : Mother Rh-negative, fetus Rh-positive
 Indirect Coomb’s test (screening test) – at 28 weeks of gestation
 Atypical antibody titer – >1:8 – risk for fetus

 Delivery if gestational age >34 weeks

Abortion
No cervical dilatation Cervical dilatation present
Missed
Non-viable
pregnancy
Suction D&C
or
Conservative
until
spontaneously
aborted
Threatened
Viable pregnancy
No intervention is
generally
indicated.
Mx: Regular out
patient followup
Inevitable
Product of
conception
not passed
Emergency
suction D&C
Incomplete
Some Product
of conception
has passed
Emergency
suction D&C
Uterine fundus less than dates (< 20 weeks)
Absence of fetal movement (> 20 weeks)
Absent heart activity on US
Management
DIC present
Emergency delivery
DIC absent
Suction D&C (< 20 weeks)
Induction of labor (> 20 weeks)

Fetal Demise

 Prevention : RhoGAM is given to Rh-negative mother at 28-weeks of gestation, within 72-hrs of amniocentesis, D&C, chorionic villous sampling and delivery of Rh-positive baby

 Kleihauer-Betke test : measure the volume of fetal RBCs in maternal circulation

■ Premature Rupture of Membrane (PROM) :

 Pooling positive, Nitrazine positive (paper turns blue), fern positive

 If uterine contraction present, Tocolysis is contraindicated

 If infection present – cervical culture, antibiotics, prompt delivery

 If infection absent – management depends upon fetal maturity

 >36 wks – prompt delivery

 Chorioamnionitis signs & symptoms : maternal fever, uterine tenderness, PROM, absence of UTI or URI

■ Preterm labor : gestational age (20-37 wks), atleast three contractions in 30 mins, cervical dilation (>2 cm) / effacement

 Bed rest & IV hydration (first step), IV MgSO4, steroids, cervical cultures, antibiotics

 Ritodrine (only FDA approved tocolytics) – beta-agonist [side effects – hypotension, tachycardia, hyperglycemia, hypokalamia, pulmonary edema]

■ Post term labor : >42 wks of gestation

 Dates sure, favorable cervix – aggressive management

 Dates sure, unfavorable cervix – cervical PGE2 followed by IV oxytocin

 Dates unsure – conservative management & await spontaneous labor

HTN in Pregnancy
Gestational HTN
BP - 140/90 mm of Hg
after 20 wks
without proteinuria
Conservative
management
Mild Preeclampsia
BP - 140/90 mm of Hg
1-2 + proteinuria
Hemoconcentration
Delivery is the only
definitive cure
< 36 wks –
conservative in the
hospital
> 36 wks – delivery
IV oxytocin + IV
MgSO4
Severe Preeclampsia
BP - 160/110 mm of Hg
3-4 + proteinuria
Hemoconcentration
Thrombocytopenia
Elevated liver enzymes
Aggressive prompt
delivery at any
gestational age
IV MgSO4 to prevent
Eclampsia

■ Eclampsia : Preeclampsia + seizure

 Aggressive prompt delivery at any gestational age after stabilization of mother

 Intracerebral hemorrhage – most common cause of death in eclampsia

■ Chronic HTN : BP - 140/90 mmHg before 20 wks of gestation; conservative management for mild-moderate HTN / Methyldopa; DBP should be maintain b/w
90-100 mmHg – Drug of choice for chronic HTN & diabetic nephropathy in
pregnancy: Labetalol (ACE inhibitors are contraindicated)
 DOC for hypertensive emergency in pregnant women – Labetalol / Hydralazine

■ HELLP syndrome : Hemolysis, Elevated Liver enzymes and Low Platelet count; Tx: aggressive prompt delivery at any gestational age + IV MgSO4 to prevent eclampsia
■ Symmetric IUGR – both head & body – usually before 28 wks. (chromosomal
abnormality, infection)
■ Asymmetric IUGR – Head is spare & body affected – usually after 28 wks.
(Mother’s factors  hypertension, preeclampsia, chronic renal disease)
■ Overview of Labor :
 More than 3 contractions in 10 mins, each lasing >30 sec
 Engagement → Decent → Flexion → Internal Rotation → Extension → External Rotation
→ Expulsion (First 3 steps occur simultaneously)
 Stage-1 : Onset of contraction to complete cervical dilation (10 cm)
 Latent Phase : ends with the acceleration with cervical dilation (3-4 cm); No descent
of fetus occur; 20-hrs in Primipara & 14-hrs in Multipara
 Active Phase : ends with complete cervical dilation (10 cm); descent of fetus occur;
1.2 cm/h in Primipara & 1.5 cm/h in Multipara

 Stage-2 : ends with delivery of fetus

 Up to 2-hrs in Primipara & 1-hr in Multipara

 Stage-3 : ends with expulsion of placenta (gush of blood vaginally, decrease fundal heights, “lengthening” of umbilical cord); up to 30-mins in all women

 Stage-4 : close observation of parturient for 1-2 hrs after delivery

 Oxytocin (similar to ADH) can cause water intoxication by retention of water [which dilute Na and produce hyponatremia]

 Prolong active phase of stage-1 : Oxytocin if hypotonic contraction; Emergency C-section if contractions are adequate

 Prolong stage-2 : IV Oxytocin if hypotonic contraction

 If adequate contraction, check fetal head is engage or not

 If head engage, consider trial of forceps or vacuum

 If head is not engaged, emergency C-section

 Prolong stage-3 : IV Oxytocin / IM Methylergomatrin / manual removal of placenta
/ hysterectomy (rarely)

 Prolapsed umbilical cord : Emergency C-section

 Preferred contraception in early post-partum period – sterilization, condom & progesterone only pills (mini pills)

 Non-reassuring FHR (fetal heart rate) tracing : Baseline rate show tachy- /bradycardia without explanation, absent acceleration, repetitive variable deceleration, repetitive late deceleration, absent variability

˗ Variable deceleration (without contraction) – fetal cord compression

˗ Early deceleration (with contraction) – fetal head compression

˗ Late deceleration (after contraction) – uteroplacental insufficiency

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Wednesday, February 24, 2010