WHOLE-BLOOD PLATELET-AGGREGATION IN MODERATE AND SEVERE PREECLAMPSIA

Objective To compare whole blood platelet aggregation in moderate and severe pre-eclampsia with normal pregnancy. Design Whole blood platelet aggregation in response to collagen, ADP, PAF, adrenalin and arachidonic acid was measured in the pre-eclampsia group at 36 weeks gestation and at 1, 24 and 48 h and at five days and six weeks post delivery. The normal pregnancy group were studied serially at 12, 20, 28, 32, and 36 weeks gestation and at 1, 24, 48 h and six weeks post delivery. Setting Trinity College Medical School, St James's Hospital, Dublin. Subjects Thirty women with diagnosed pre-eclampsia were recruited for the study. Fifteen of these women had severe pre-eclampsia and the remaining 15 had moderate disease. The pre-eclampsia group were compared with 20 healthy primigravid women with uncomplicated pregnancies and deliveries. Results In women with severe pre-eclampsia, platelet aggregation in response to collagen, ADP, adrenalin and arachidonic acid was significantly lower at 36 weeks gestation compared with normal pregnancy. Lower levels of collagen induced aggregation were also found at 1 h post delivery when compared with normal pregnancy. Women with moderate pre-eclampsia showed a decreased response to aggregating agents at 36 weeks gestation but this was not significant. ADP, collagen and PAF induced aggregation was higher in women with moderate pre-eclampsia at 36 weeks gestation and during the early puerperium compared with severe pre-eclampsia. Conclusions The clinical signs of pre-eclampsia are accompanied by a reduction in platelet responsiveness, the extent of which is related to the severity of the disease. This suggests that an abnormal platelet activation occurs early in pregnancies destined to be complicated by pre-eclampsia. This activation may be involved in the pathogenesis of pre-eclampsia since its inhibition using low dose aspirin has been shown to modify the disease in high risk pregnancies.