Prepartum diagnosis of traumatic fetal-maternal hemorrhage.

The diagnosis of significant fetal-maternal hemorrhage due to abdominal trauma was made upon detection of fetal red cells in the maternal circulation before delivery, and prompted immediate intervention despite an equivocal fetal monitor tracing. Histologic examination of the placenta identified the area of disruption of the fetal circulation, and the clinical condition of the neonate confirmed the diagnosis. A test for fetal-maternal hemorrhage would be appropriate in the evaluation of any pregnant woman sustaining trauma to the abdomen.