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

Abstract

In clinical practice, the only tests of platelet function are bleeding time and platelet number. Bleeding time lacks sensitivity and specificity but the PFA-100, an in vitro analyser of platelet function may be of value. This study aimed to evaluate any correlation between platelet number and function 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 coagulation testing screen with the PFA-100 using collagen and epinephrine (PFA-EPI) 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) thrombocytopenia of pregnancy; Group III (n=13) women with pre-eclampsia without thrombocytopenia; Group IV (n=19) women with pre-eclampsia and thrombocytopenia. Results are expressed as mean (SD). Platelet count was not statistically different 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 III (128.3 (17.9) s), and Group IV (143.6 (47.7) s) compared with normal pregnant patients (114.6 (27.3) s, P<0.05, Mann-Whitney U-test). PFA-ADP was statistically increased only in Group II compared with normal pregnant patients (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 correlated with platelet count only in Group IV (r=-0.74, P=0.0003). The increased 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 thrombocytopenia, platelet function may be preserved when the platelet count is as low as 60 G litre(-1).

Evaluation of the platelet function analyzer (PFA-100®) vs. the thromboelastogram (TEG) in the parturient

“…The maximum amplitude (MA), a parameter measured by the TEG, has been found to correlate best with platelet count and function. 2 Vincelot et al 3 evaluated the PFA-100Ò in women with thrombocytopenia and those with preeclampsia. They were not able to find a correlation between the platelet count and CT in the parturient with or without thrombocytopenia.…”

Thrombocytémie essentielle et grossesse

“…Certains auteurs autorisent la ré alisation de l'analgé sie pé ridurale si la patiente ne manifeste aucune tendance hé morragique, si la numé ration plaquettaire est infé rieure à 1 000 000/mL et si la coagulation et la fonction plaquettaire sont normales [12,22]. Notre attitude tient compte du caractè re non fonctionnel des plaquettes en excè s. Actuellement, même le Platelet Function Analyser (PFA) dont on dispose de normes pendant la grossesse [23] ne donne pas de certitude en matiè re d'appré ciation du risque clinique d'hé morragie donc d'hé matome intrarachidien compressif dans les thrombopathies. Aucun test biologique ne nous permet d'appré cier ce risque et notre é quipe d'anesthé sie adopte donc actuellement une attitude de prudence.…”

A Review of Hemostasis in Normal Pregnancy and Puerperium

“…The collagen membrane used in PFA-100 is impregnated with platelet activators (ADP and epinephrine). Mean closure time using epinephrine was reported as 105±18 seconds [35] and 114.6±27.3 seconds [36] in 93 and 110 healthy pregnant women respectively. Both studies did not include a control group of non-pregnant women.…”

“…It is important that laboratories analyzing coagulation profile in pregnant women should use these reference intervals. Moreover, reference intervals for global hemostatic testing such as platelet function [35,36] and thromboelastography [57,59] in normal pregnancy have also been defined.…”