Meckel-Gruber syndrome. Importance of prenatal diagnosis.

Prenatal sonographic findings are reported in six fetuses with the Meckel-Gruber syndrome to illustrate the variety of sonographic findings associated with this disorder and to emphasize the importance of prenatal sonography in helping to establish the correct diagnosis. All six fetuses demonstrated evidence of renal cystic dysplasia. In five cases the kidneys were large and echogenic, demonstrating small discrete cysts in the range of 2 to 5 mm. The remaining fetus demonstrated unilateral renal cystic dysplasia and contralateral renal agenesis. Oligohydramnios was noted in all cases and was evident as early as 14 weeks. An occipital cephalocele was demonstrated on sonography in each case although the size and contents of the cephalocele varied significantly. Two fetuses, both in the same family, also demonstrated a cystic mass in the posterior fossa and partial absence of the cerebellum consistent with a Dandy-Walker variant or cerebellar hypoplasia. The concurrence of marked oligohydramnios and bilateral severe renal anomalies should initiate a search for anomalies of the central nervous system indicative of the Meckel-Gruber syndrome. Recurrence of Meckel-Gruber syndrome may be evaluated as soon as 14 weeks, but it may not be reliably excluded until 20 weeks.