OB Lab Tests Flashcards
Triple Screen
HCG estriol AFP
Trisomy 21: dec AFP & estriol, inc HCG
Trisomy 18: dec AFP, estriol, & HCG
Having a 5.0MOM (measures of the mean) in AFP can be a strong indication for what abnormality
Omphalocele
Quad Screen
HCG estriol AFP inhibin A
Inc Down syndrome detection.
Nuchal Lucency
< 3 mm normal
> or = abnl
Assoc with chromosomal anomalies, cardiac anomalies, poor fetal growth, preg fail.
11-14 weeks GA
Use + calipers
Fetus mid sag plane. No hyper extension or hyper flexion of neck. Amnion must be separate.
MSAFP
Asses neural tube defects. Also asses abd wall defects, ABS, cystic hygromas, teratoma, renal abnl, GI obstruct, & placenta aberrations
15-20 wks
AFP produced in fetal liver
Inc with maternal liver disease, twins, fetal death, twins, misdated pg, norm
Dec with trisomies, no pg, molar pg, fetal death, misdated pg, norm
Genetic testing
23 pairs of chromosomes. 22 + xx or xy
Stained DNA
Chorionic Villi Sampling
9-12 weeks
Samples placenta
Diagnostic
Amniocentesis
14 wks
Samples amniotic fluid once amnion is fused.
Diagnostic
Fluorescence In Situ Hybridization FISH
Fast results 24 hrs
Tri 21 13 18 22
Lecithin/Spingomyelin Ratio
Steroid injected into lungs to see if mature
> 2.1 = normal
Maturity may be delayed with diabetes and accelerated with severe diabetes & chronic HTN
HCG
Inc highly with molar pregnancy
Inc with twins
Dec with ectopic
Doubles every 2 days
Cell Free DNA
Extremely accurate but not diagnostic. Detects tri 13, 18, 21
Non invasive
HCG for sac seen TA & TV
TA: 1800mIU/ml
TV: 500mlU/ml
HCG should double every 2 days
Mosaisism
Norm and abnl collection in placenta in CVS. Placenta cells may not always be the same as fetal cells.
2.5 MOM of MSAFP is
Normal
