Pregnancy Associated Thrombotic Thrombocytopenic Purpura: A Case Report.

Introduction: In clinical setting, cases with thrombotic thrombocytopenic purpura (TTP) are easily mis-diagnosed and the clinical outcome may be influenced by the mis-diagnosis.

Case report: The patient is a 28-year-old woman in her first pregnancy. She had transient thrombocytopenia two years ago and was diagnosed idiopathic thrombocytopenic purpura (ITP) based on her bone marrow results but recovered quickly without immunosuppressive therapy. Her blood routine test was normal before the pregnancy. But she was found to have asymptomatic thrombocytopenia during her first pregnancy check-up in the first trimester of her pregnancy. A diagnosis of ITP was made after bone marrow examination. Then, she was put on a course of oral prednisolone and her platelet count transiently increased to normal but decreased to 18×10⁹/L after she cut down on the dose. After that, she only showed partial response to increased dose of oral prednisolone and her hemoglobin (Hb) level began to fall slowly. She was admitted during her second trimester of gestation complaining of headache and low fever with signs of agitation. Blood routine, blood smear analysis, urine routine, liver function and blood bilirubin analysis, renal function tests were performed regularly. Bone marrow smear examination, tests for detecting various causes of hemolysis and tests detecting autoimmune antibodies were also performed. Her lab tests were indicative of severe hemolytic anemia and thrombocytopenia. Her renal function was continuously normal. As other causes of hemolysis and autoimmune diseases were excluded, a diagnosis of Evan’s syndrome was made although the Coombs’ test was negative. She showed partial response to high-dosage of prednisolone and IgG with increased but not normal platelet count and her fever disappeared. After transfusion of packed RBC and platelets, her symptoms and signs of the central nervous system disappeared and the fetus was removed through cesarean section. 22 days later, she underwent an emergent exploratory laparotomy confirming acute necrotic cholecystitis under supportive transfusion, and splenectomy was also performed. But the hemolytic anemia and thrombocytopenia still went on although she was still administered prednisolone and high-dosage of IgG. As a diagnosis of TTP was suspected, she received plasma exchange. The next day, her Hb level increase to 97g/L and her platelet count increased to 500×10⁹/L without transfusion. More than one month later, her plasma sample was sent to another center to detect ADAMTS13 level and was found to be deficient in ADAMTS13 (7%). But antibody to ADAMTS13 was not detected.

Conclusion: The cause of anemia and thrombocytopenia in this case was pregnancy associated TTP. Further experiment for detection of mutation in her ADAMTS13 gene is being done. Mis-diagnosis in this case may be related to lack of recognition of variation in the course, precipitating factors of the disease and unavailability of ADAMTS13 level test.