Diagnostic value of maternal serum alpha fetoprotein for predicting pregnancy outcome in high risk pregnancies: an epidemiological perspective.

This study was conducted on high risk pregnancies, between 6-40 weeks of gestation, to evaluate the difference in maternal serum alphafetoprotein (MSAFP) levels in normal and abnormal pregnancies. It's predictive value for pregnancy outcome was calculated. Age and parity matched, normal pregnant women with normal pregnancy outcome were taken as controls. It was determined that the overall sensitivity (75.6%) and specificity (83.7%) was not very good for diagnostic purposes. On the contrary in patients with neural tube defects, congenital anomalies, early pregnancy complications leading to fetal death, still birth, neonatal deaths, Rh incompatibility and preterm deliveries the specificity was (96%-100%), due to very few false positives but sensitivity was comparatively low (75%-89%) due to many false negatives. As a result the predictive value of a negative test in these conditions was very high (80%-100%), though that of a positive test was comparatively low (60%-89%). This establishes a diagnostic value of MSAFP, especially in high risk pregnancies as opposed to its use as a screening test for all pregnancies. This is of special value for a poor country like India, where it is not possible to screen total pregnant population due to economic and logistic reasons.