Trisomy 21, fetal hydrops, and anemia: Prenatal diagnosis of transient myeloproliferative disorder?

Background: Aneuploidy is frequently cited as an etiology of hydrops fetalis. Traditionally, associated anomalies (specifically cardiovascular abnormalities) have been postulated as the causative factor. Cases: We report two cases of severe anemia associated with hydrops in fetuses that later proved to have Down syndrome. The hematocrit in both fetuses was markedly decreased. The white blood cell count was normal in one but greatly elevated in the other; the latter infant had thrombocytopenia. These findings are consistent with transient myeloproliferative disorder. Conclusions: Nonimmune fetal hydrops and trisomy 21 may be associated without cardiac or anatomical anomalies. Transient myeloproliferative disorder has been seen in neonates with trisomy 21 and may be a cause of hydrops in some aneuploid fetuses. Chromosomal analysis should not be excluded in the workup of nonimmune hydrops when anemia is found, and therapy may be withheld until karyotyping has been performed. (Obstet Gynecol 1993;82: 703–5).