Causes of thrombocytopenia in triplet gestations

The purpose of this study was to determine the incidence and cause of thrombocytopenia in triplet gestations.

All triplet gestations that received prenatal care and were delivered at our hospital between 1993 and 2001 were identified. Serial platelet values were reviewed from the earliest gestational age available until the postpartum period. Mild and severe thrombocytopenia were defined as a platelet count of 100000 to 150000/microL and <100000/microL, respectively. The cause of the thrombocytopenia was determined from a review of medical records.

One hundred twenty-six triplet pregnancies met the inclusion criteria. The mean maternal age was 34.3 +/- 5.4 years, 85.7% of the patients were nulliparous, and at least 92.1% of the patients had received infertility treatment. The overall rate of thrombocytopenia in our triplet population was 36.5%. Mild thrombocytopenia occurred in 19.0% of pregnancies, and severe thrombocytopenia occurred in 17.5% of pregnancies. The causes of thrombocytopenia were severe preeclampsia (54.3%), gestational (23.9%), mild preeclampsia (8.7%), HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count syndrome; 4.3%), atypical preeclampsia (4.3%), idiopathic thrombocytopenic purpura (2.2%), and familial (2.2%). Thrombocytopenia occurred significantly earlier before the diagnosis of preeclampsia.

Approximately one third of triplet gestations are complicated by thrombocytopenia, one half of which are severe. This represents a much higher frequency as compared with the 6.6% to 11.6% that was reported for singleton gestations. Hypertension-associated disorders of pregnancy account for 71.7% of thrombocytopenia in triplets, unlike singleton gestations in which 75% of thrombocytopenia is gestational. The single most common cause of thrombocytopenia in triplets is severe preeclampsia. This is the first study to evaluate the incidence and cause of thrombocytopenia in a large set of triplet gestations.