Percutaneous umbilical cord blood sampling in the evaluation of fetal platelet counts in pregnant patients with autoimmune thrombocytopenia purpura.

Autoimmune thrombocytopenia purpura in pregnancy is associated with fetal thrombocytopenia. Twenty-one patients with autoimmune thrombocytopenia purpura (22 fetuses) underwent 26 umbilical cord punctures to assess the fetal platelet count. Blood could not be obtained from one fetus. Thrombocytopenia (less than 150,000/microL) was found in five cases, but in none was it of sufficient degree to preclude vaginal delivery. Persistent fetal bradycardia necessitating emergency cesarean delivery occurred in two cases. Umbilical cord puncture was found to be technically more difficult in the term fetus than in the second-trimester fetus studied in previous investigations.