Platelet function during pregnancy: an evaluation using the PFA-100 analyser

In clinical practice, the only tests of platelet function are bleeding time and platelet number. Bleeding time lacks sensitivity and specificity but t he PFA-100, an in vitro analyser of platelet function may be of value. This study aimed to evaluate any correlation between platelet number and functi on using the PFA-100 in pregnant women. During a 21-month period, platelet function was evaluated in whole blood as part of the pre-anaesthetic coagul ation testing screen with the PFA-100 using collagen and epinephrine (PFA-E PI) or ADP (PFA-ADP) as platelet agonists. Thrombocytopenia was defined as a platelet number less than 150 G litre(-1). The patients were divided into four groups: Group I (n=110) normal pregnancy; Group II (n=38) thrombocyto penia of pregnancy; Group III (n=13) women with pre-eclampsia without throm bocytopenia; Group IV (n=19) women with pre-eclampsia and thrombocytopenia. Results are expressed as mean (SD). Platelet count was not statistically d ifferent between Groups II and IV (111.1 (23.1) vs 99.5 (28.0) G litre(-1)) . PFA-EPI was statistically increased in Group II (124.0 (26.3) s), Group I II (128.3 (17.9) s), and Group IV (143.6 (47.7) s) compared with normal pre gnant patients (114.6 (27.3) s, P<0.05, Mann-Whitney U-test). PFA-ADP was s tatistically increased only in Group II compared with normal pregnant patie nts (90.5 (18.9) vs 80.2 (11.2) s, P<0.05). PFA values were increased above normal laboratory values in (four of 38) Group II patients and (six of 19) Group IV patients but in no patients in Group III. PFA-ADP results were co rrelated with platelet count only in Group IV (r=-0.74, P=0.0003). The incr eased PFA values and the correlation between PFA-ADP and platelet number in hypertensive thrombocytopenic women confirms that platelet function may be decreased in such patients. In patients with pregnancy-induced thrombocyto penia, platelet function may be preserved when the platelet count is as low as 60 G litre(-1).