Reverse end-diastolic umbilical artery blood flow at 11 weeks' gestation.

This report describes a case of reverse end-diastolic blood flow in the umbilical artery of one of the fetuses of a twin pregnancy at 11 weeks' gestation. Cytogenetic studies after amniocentesis performed at 12 weeks revealed a 45.X karyotype of this twin whose death was registered 1 week later. Spontaneous delivery of the co-twin occurred at 37 weeks; the newborn was healthy and normal. This is the earliest record of reverse diastolic flow in the umbilical artery. Even in the first trimester of pregnancy this is an ominous sign and fatal demise is expected.