OB Flashcards
(111 cards)
where is AFP produced
fetal yolk sac and liver
what is elevated AFP
> 2.5 MoM (multiples of median)
What causes increase in AFP?
What about decrease
Increase: open NTD, abd wall defect, multiples, fetal maternal hemorrhage, germ cell tumor, fetal demise, placental conditions, underestimation of GA
Decrease with T21
what should you do if you have elevated MSAFP
evaluate with US, correct GA consider amnio
Dont need increased antenatal surveillance based on isolated elevated AFP
Criteria for breech vaginal delivery
counseled on risk of cord prolapse or head entrapment
37weeks plus
No prior CD
2500-4000g
frank or complete breech
normal AFI
adequate pelvis
no fetal anomalies
non hyperextended neck
spontaneous/normal labor course
experienced provider
% of preg breech
% of CS for breech
3-4 % of pregnancies are breech
17% of CS due to breech
risk of fetal death with FGR <10% and <5%ile
<10: 1.5%
<5: 2.5%
risk of recurrence for prior preg with FGR
20%
when to offer genetic counseling +/- amnio for FGR
-diagnosed before 32w
-FGR + poly
-fetal malformation
Major markers for T21
duodenal atresia
Cardiac (ASD, TOF, AV canal defects)
Soft markers
Which have the highest liklihood ratios
Which one is the best predictor
echogenic cardiac focus
pyelectasis
short femur length
choroid plexus cyst
echogenic bowel, thickened NT, and ventriculomegaly even when isolated are higher likelihood ratio
isolated finding of thickened nuchal skin highest risk of aneuploidy
what is the importance of NT and nasal bone
NT detection rate for T21 being 64-70%
cystic hygroma associated with T21 in about 50% of cases
Hypoplastic or absent nasal bone can be detected in 62-70% of fetuses with down syndrome, only 1% of normal fetuses
1/3 of cases with thickened NT will have chromosomal defects, T21 accounts for 50% of those
omphalacele
1:5000
midline defect in abdominal contents herniate
covered by amnion and peritoneum
has liver herniation
can look like normal embryo at 9-11 weeks
50% associated with cardiac defects
defects larger than 5 cm delivered by CS
umbilical cord insertion at apex of defect
gastroschisis
1:2500
full thickness defect, R paraumbilical
no liver herniation
no overlying membrane
never looks like normal embryo
no increase in chromosomal abnormalities
can deliver vaginally, immediate repair. can be done if you can return abd contents, in about 80% of cases
when to change EDD based on GA and CRL discrepancy from LMP
if < 9w, change if more than 5d
from 9-15w6d, change if more than 7d
from 16w-21w6d, change if more than 10d
from 22w to 27w6d change if more than 14d
from 28w and up, change if more than 21d
risk factors for NTDs
-environmental factors
-medications (anti epileptics carbamazepine, valproic acid)
-maternal hyperthermia
-obesity
-hispanic population
-genetics. chances if 1 prior sibling is 3.2%, two prior is 10%
what women are at high risk of NTD and what dose should they take
4 mg (4000 mcg) 3 mo before pregnancy and continue until 12w
women with previous preg affected by NTD
women who are affected by NTD themselves
those who have a partner affected
those who have a partner with a previous affected child
folate resistant NTDs
poor glucose control in first trimester
hyperthermia
obesity
aneuploidy
genetic disorders
those on anti epileptic meds
Delivery timing for FGR
EFW 3-10%, no concurrent findings
38-39 w0d per smfm (39w6d per acog)
delivery timing for EFW <3%ile, no concurrent findings
37w or at time of diagnosis if later
Elevated UAD delivery timing
37 weeks
Absent end diastolic flow delivery timing
33-34w
reversed end diastolic flow delivery timing
30-32w
delivery timing with FGR and concurrent conditions (oligo, preeclampsia, cHTN)
34-37w6d