Prenatal diagnosis of transient myeloproliferative disorder via percutaneous umbilical blood sampling. Report of two cases in fetuses affected by Down's syndrome.

Since its initial description in 1982, percutaneous umbilical blood sampling has become useful in diagnosing, monitoring, and even treating a variety of fetal disorders. Recently two percutaneous umbilical blood samples were evaluated in which the white blood cell count was markedly elevated with many circulating blasts. Both samples exhibited the morphologic features of a transient myeloproliferative disorder, characteristically seen in neonates and infants with Down's syndrome. In both cases, antenatal clinical and ultrasound abnormalities also were suggestive of Down's syndrome, which was confirmed by cytogenetic studies. Although the peripheral blood abnormalities persisted at birth, both patients experienced spontaneous remission of the transient myeloproliferative disorder by 5 weeks of age. To our knowledge, these two cases of Down's syndrome represent the first reported examples of the intrauterine diagnosis of transient myeloproliferative disorders.