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 platele t aggregation in response to collagen, ADP, PAF, adrenalin and arachid onic acid was measured in the pre-eclampsia group at 36 weeks gestatio n 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, an d 36 weeks gestation and at 1, 24, 48 h and six weeks post delivery. S etting Trinity College Medical School, St James's Hospital, Dublin. Su bjects Thirty women with diagnosed pre-eclampsia were recruited for th e study. Fifteen of these women had severe pre-eclampsia and the remai ning 15 had moderate disease. The pre-eclampsia group were compared wi th 20 healthy primigravid women with uncomplicated pregnancies and del iveries. Results In women with severe pre-eclampsia, platelet aggregat ion in response to collagen, ADP, adrenalin and arachidonic acid was s ignificantly lower at 36 weeks gestation compared with normal pregnanc y. Lower levels of collagen induced aggregation were also found at 1 h post delivery when compared with normal pregnancy. Women with moderat e pre-eclampsia showed a decreased response to aggregating agents at 3 6 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 seve re pre-eclampsia. Conclusions The clinical signs of pre-eclampsia are accompanied by a reduction in platelet responsiveness, the extent of w hich is related to the severity of the disease. This suggests that an abnormal platelet activation occurs early in pregnancies destined to b e complicated by pre-eclampsia. This activation may be involved in the pathogenesis of pre-eclampsia since its inhibition using low dose asp irin has been shown to modify the disease in high risk pregnancies.