Prenatal diagnosis of the Meckel-Gruber syndrome from 11th to 20th gestational week.

Introduction: The Meckel-Gruber syndrome (MKS) is a rare autosomal recessive disorder that is characterized by typical sonographical findings: occipital encephalocele, postaxial polydactyly and cystic enlargement of the kidneys. Its recurrence risk of 25 % demands an exact diagnosis.

Method: Retrospective analysis of the sonographic characteristics in relation to the gestational age in eight cases with the pathologic diagnosis of MKS.

Results: The sonographic characteristics depend on the gestational age. The classic trias was solely seen in the case diagnosed before 14 (th) week of gestation. In the other seven cases, diagnosed between the 17 (th) and 20 (th) week of gestational age, only two of three characteristic signs of MKS could be visualised by US. Polydactyly was missed by ultrasound in all seven cases due to the marked oligohydramnion.

Conclusion: The Meckel-Gruber syndrome can be confidently detected and diagnosed by sonography at the 11th to 14th gestational week. Later in the pregnancy, severe oligohydramnion makes it more difficult to establish the diagnosis by US alone. In these cases a meticulous autopsy is necessary to establish the diagnosis of MKS.