Fetal hepatosplenomegaly: an isolated sonographic sign of trisomy 21 in a case of myeloproliferative disorder.

Enlargement of the fetal liver and spleen as well as oligohydramnios were the only pathological sonographic signs detected in a pregnant woman presenting because of decreased fetal movements at 31 weeks' gestation. Doppler examination of fetal vessels revealed pathological values (absent or reversed flow in the umbilical artery, centralization of fetal circulation). No hydrops development or any further malformations were seen. The association of pathological Doppler findings with hepatosplenomegaly roused the suspicion of fetal infection. The infant had to be delivered because of deterioration of fetal heart rate patterns 2 days later. The newborn had Down's syndrome and the confirmed hepatosplenomegaly was found to be due to a transient myeloproliferative disorder with severe leukocytosis and predominance of immature blast forms. Hematological parameters normalized without specific therapy within 3 weeks. Although transient leukemic reactions have been diagnosed prenatally in cases of Down's syndrome associated with non-immune hydrops, to our knowledge this is the first reported case of isolated hepatosplenomegaly visualized by prenatal ultrasound as a sign of trisomy 21. The presence of fetal hepatosplenomegaly has to be taken into consideration as a possible marker for trisomy 21 and not only for infectious or metabolic diseases.