Fetal hydrops and hepatosplenomegaly in the second half of pregnancy: a sign of myeloproliferative disorder in fetuses with trisomy 21.

OBJECTIVE: To demonstrate the relationship between fetal hydrops and/or hepatosplenomegaly in the second half of pregnancy with a myeloproliferative disorder in fetuses with trisomy 21 or mosaic trisomy 21.
DESIGN: A retrospective case series.
SUBJECTS: Cases were selected from 79 cases of trisomy 21 diagnosed in our prenatal unit between 1993 and 1999.
METHODS: All fetuses had a detailed sonographic anatomic survey and biometry. Doppler of the umbilical and middle cerebral arteries, ductus venosus, inferior vena cava and umbilical vein was performed whenever possible. Two-dimensional echocardiography supplemented by color Doppler flow mapping and spectral pulsed wave Doppler was performed in all cases of fetal hydrops. Fetal karyotyping was obtained by amniocentesis, chorionic villus sampling or fetal blood sampling. In the presence of fetal hydrops a cordocentesis was performed for fetal hematology, biochemistry and TORCH serology. In cases with diagnosis of myeloproliferative disorder, peripheral blast cells were characterized by microscopy, cytochemistry and determination of surface markers. All cases with myeloproliferative disorder were stillborn and subsequently had a postmortem examination performed.
RESULTS: During the study period 79 cases of trisomy 21 were diagnosed. Eleven of these had fetal hydrops. Three of these fetuses presented with hepatosplenomegaly and myeloproliferative disorder in the second and third trimesters. In addition, one fetus with sonographic markers of trisomy 21, where karyotyping was unfortunately unsuccessful, presented with hepatosplenomegaly, hydrops and myeloproliferative disorder. In the four fetuses with hepatosplenomegaly and hydrops, serology was negative for congenital infection. The characteristics of blast cells in the peripheral blood smear revealed a myeloproliferative disorder.
CONCLUSION: Fetal hydrops and/or hepatosplenomegaly in the second half of pregnancy, although suggestive of infectious etiology, may be a sign of myeloproliferative disorder in fetuses with trisomy 21 or mosaic trisomy 21. There is a possibility that a transient myeloproliferative disorder is a more common cause of mid or late-trimester hydrops in cases of trisomy 21 than previously thought. In these hydropic fetuses the prognosis seems to be poor. On the other hand we can speculate that a myeloproliferative disorder and the associated hepatosplenomegaly and/or hydrops may show spontaneous remission or that the transient myeloproliferative disorder may be without any detectable ultrasonographic signs and therefore may be more frequent in utero than realized.