A successfully treated case of an acute presentation of congenital thrombotic thrombocytopenic purpura (Upshaw-Schulman syndrome) with decreased ADAMTS13 during late stage of pregnancy.

We herein report the case of a 28-year-old pregnant woman with an acute presentation of remarkable petechiae on her lower extremities and severe thrombocytopenia (16 000/mm3 ) at the 35th week of gestation. Although idiopathic thrombocytopenic purpura was initially suspected, subsequent examinations revealed that her ADAMTS13 (a Disintegrin And Metalloprotease, with ThromboSpondin type 1 repeats, member 13) titer was extremely decreased, while she was negative for antibodies against ADAMTS13. Infusion of fresh frozen plasma was immediately performed, and the platelet count was observed to increase. However, severe pregnancy-induced hypertension and proteinuria emerged at 36 weeks and 2 days of gestation, and a male infant was delivered by emergency cesarean section on the 37th week of gestation. The postnatal development was uncomplicated. After delivery, although the mother's platelet count and ADAMTS13 activity decreased temporarily, both values increased following fresh frozen plasma transfusion. This case showed interesting aspects of congenital thrombocytopenic purpura (Upshaw-Schulman syndrome) in pregnancy. Moreover, the rapid measurement of the patient's ADAMTS13 activity and the subsequent accurate diagnosis of congenital thrombocytopenic purpura made it possible to treat the patient with fresh frozen plasma infusion and avoid contraindicated platelet infusion. Close cooperation between obstetricians, hematologists and pediatricians is necessary to achieve successful outcomes in cases of thrombocytopenic purpura during pregnancy.