Ultrasonographic parameters in the prenatal diagnosis of Meckel syndrome.

The ability to make a prenatal diagnosis of Meckel syndrome (encephalocele, polydactyly, and polycystic kidney) by ultrasound is described. Three cases are detailed; in 2 of these the diagnosis was made at 18 and 36 weeks' gestation, respectively. In case 1 Meckel syndrome was identified by the presence of oligohydramnios, microcephaly, and enlarged cerebral ventricles. In case 2 oligohydramnios was associated with an encephalocele, bilateral renal enlargement, and a polydactyly. In case 3 the diagnosis was excluded in a fetus at risk. The usefulness of ultrasound in making this diagnosis is discussed for cases in which the amniotic fluid alpha-fetoprotein value is normal, inconclusive, or unobtainable.