Lupus anticoagulant (LA) and anti-cardiolipin antibodies (ACAs) are acquired antiphospholipid antibodies (APAs), which are considered to be important markers for pregnancy losses and intrauterine fetal demise. LA and ACAs have anticoagulant effects in vitro and thrombotic effects in vivo and are considered to be the cause of recur-rent pregnancy losses (RPLs), resulting from placental vascular thrombosis and infarction. The aim of this study was to identify the most sensitive and specific method of deter-mining APA positivity and to evaluate the prevalence of APA in patients with unex-plained RPL. The experiment consisted of 25 women with unexplained RPL, the patient group, and 15 healthy women with successful pregnancies, the control group. ACA positivity was deter-mined with ELISA and LA activity with phos-pholipid dependent coagulation tests (PDCTs): prothrombin time (PT), activated partial thromboplastin time (APTT), kaolin clotting time (KCT) and a platelet neutralization procedure (PNP). LA activity was detected in 5 of the 25 women in the experimental group (20%), but in none of the 15 women in the control group Increased ACA levels were observed in 8 of the experimental group (32%) and in one of the control group subjects (7%). These results provide quantitative evidence of the association between APA and RPL. LA was best identified through KCT and should be specifically confirmed by PNP. Screening for APAs, both with ACAs for sensitivity and LA for specificity, is indicated in patients with adverse pregnancy outcomes.

Lupus anticoagulant (LA) and anti-cardiolipin antibodies (ACAs) are acquired antiphospholipid antibodies (APAs), which are considered to be important markers for pregnancy losses and intrauterine fetal demise. LA and ACAs have anticoagulant effects in vitro and thrombotic effects in vivo and are considered to be the cause of recur-rent pregnancy losses (RPLs), resulting from placental vascular thrombosis and infarction. The aim of this study was to identify the most sensitive and specific method of deter-mining APA positivity and to evaluate the prevalence of APA in patients with unex-plained RPL. The experiment consisted of 25 women with unexplained RPL, the patient group, and 15 healthy women with successful pregnancies, the control group. ACA positivity was deter-mined with ELISA and LA activity with phos-pholipid dependent coagulation tests (PDCTs): prothrombin time (PT), activated partial thromboplastin time (APTT), kaolin clotting time (KCT) and a platelet neutralization procedure (PNP). LA activity was detected in 5 of the 25 women in the experimental group (20%), but in none of the 15 women in the control group Increased ACA levels were observed in 8 of the experimental group (32%) and in one of the control group subjects (7%). These results provide quantitative evidence of the association between APA and RPL. LA was best identified through KCT and should be specifically confirmed by PNP. Screening for APAs, both with ACAs for sensitivity and LA for specificity, is indicated in patients with adverse pregnancy outcomes.