Meckel-Grüber syndrome: sonography and pathology.

Objective: To define a specific sonographic pattern for the appearance of the kidneys in fetuses affected by Meckel-Grüber syndrome (MGS).

Methods: This was a retrospective analysis of 30 cases, collected from five centers, with ultrasound features suggestive of MGS. Only fetuses with a confirmed diagnosis of MGS were finally included. Analysis included a detailed evaluation of the sonographic findings and comparison with pathological follow-up.

Results: Seventeen cases met the pathological criteria for a diagnosis of MGS and were included in the study. In all cases, a typical sonographic pattern was seen: the kidneys were enlarged (mean, + 4.8 SD) and showed unusual corticomedullary differentiation, occurring as early as the first trimester. In most cases, the medullary areas appeared excessively large and mottled due to the presence of multiple small cysts.

Conclusions: The kidneys of fetuses with MGS are enlarged, cystic and have unusual corticomedullary differentiation. These features can be observed as early as the first and early second trimesters.