[Role of platelet microaggregates in thrombocytopenia in normal and hypertensive pregnancy].

Platelet count and parameters (mean volume, MPV; volume distribution width, PDW; percent of large elements, PLCR) were examined at the third trimester, at delivery, at days 1 and 4 puerperium, in 9 primigravidae with idiopathic thrombocytopenia and 11 with pregnancy-induced hypertension (PIH) with associated thrombocytopenia, and compared with those from 27 PIH and 22 normotensive, normothrombocytemic primigravidae. All hypertensive women were treated with nifedipine alone or associated to methyldopa, clonidine or labetalol. Platelet count tends to a progressive fall during normal pregnancy, and to rough rise in puerperium, the remaining parameters being unchanged. In idiopathic thrombocytopenia the reduced count remains unchanged even in puerperium, and the increased MPV and PLCR are consistent with the presence of large, immature, circulating elements, in pregnancy as well as in puerperium. When thrombocytopenia is associated to PIH, puerperal recovery is maximum. In this case, the drop in MPV and PLCR is consistent with the resolution of microaggregates that may produce artifact in the evaluation of platelet parameters. The presence of platelet microaggregates may therefore cause overestimation of thrombocytopenia associated to PIH.