Rapid assay--possible application in the diagnosis of premature rupture of the membranes.

Premature rupture of the membranes frequently presents a diagnostic dilemma to the clinician. The presence of alpha-fetoprotein (AFP) in amniotic fluid suggests a possible solution. A rapid, easy-to-use latex agglutination test for AFP was evaluated on 99 amniotic fluid samples of known AFP concentration. Body fluids (maternal serum, urine, vaginal secretions, and seminal fluid) that commonly interfere with other tests were also studied. The sensitivity for amniotic fluids from gestations less than 39 weeks was 93%, and specificity was 94%. The test is most accurate under 35 weeks, when diagnosis is critical. Equivocal results may be resolved by using radioimmunoassay. The results suggest that a rapid assay for AFP may be useful in the diagnosis of ruptured membranes. It has few interfering factors, is safe, and requires no elaborate equipment or training.