Prenatal diagnosis of exstrophy of the cloaca.

While screening for neural tub defects, three cases of exstrophy of the cloaca were found through elevated second-trimester maternal serum alphafetoprotein levels. Measurement of amniotic fluid alphafetoprotein and examination of the structure of rapidly adhering cells confirmed the abnormalities, and the pregnancies were terminated. Subsequent studies of cholinesterase isozymes by acrylamide electrophoresis showed an abnormal acetylcholinesterase band in each of the three amniotic fluids. During the same period, two more cases of exstrophy of the cloaca were identified in spontaneous abortions and another one in a stillbirth. It is suggested that the condition is more common than has been previously suspected and is often misclassified as omphalocele.