Can gestational dates routinely derived from very early ultrasound be used to interpret maternal serum alpha-fetoprotein measurements?
This study assesses the reliability of estimating gestational age via crown-rump or gestational sac measurements obtained at 8 weeks' gestation or earlier as part of routine physician office practice. To accomplish this, we studied 88 pregnancies managed at 45 different sites in which both an early first-trimester ultrasonically-derived gestational age estimate and a second-trimester biparietal diameter (BPD) estimate were available. The first- and second-trimester determinations were highly correlated, but the first-trimester determinations were, on average, 0.43 weeks earlier than the second. The first-trimester estimates were satisfactory for use in interpreting maternal serum alpha-fetoprotein (MSAFP) screening measurements, but second-trimester BPD measurements obtained prior to MSAFP screening should be the method of choice for interpreting MSAFP values, due to the increased sensitivity for detecting open spina bifida.
Haddow
J E
JE
Foundation for Blood Research, Scarborough, ME 04070-0190.
Holman
M S
MS
Palomaki
G E
GE
D005260:Female; D005865:Gestational Age; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D016216:Ultrasonography, Prenatal; D000509:alpha-Fetoproteins / Q000032:analysis*
D000509:alpha-Fetoproteins