The prevalence of lupus anticoagulant in normal pregnancy and in women with recurrent fetal loss—recommendations for laboratory testing for lupus anticoagulant

BACKGROUND: There is wide disagreement in the literature on the rate of detection of lupus anticoagulant (LA) in women with recurrent fetal loss (RFL). The aim of this study was to determine the prevalence of LA using four phospholipid-dependant coagulation tests in a large population of Saudi women. PATIENTS AND METHODS: We determined the prevalence of LA in women with RFL (n=925), normal pregnancy (n=663), and in healthy blood donors (n=204), at the King Khalid University Hospital, Riyadh. The following coagulation tests were employed: the activated partial thromboplastin time (APTT), platelet neutralization procedure (PNP), kaolin clotting time (KCT) and the dilute Russel's viper venom test (dRVVT). RESULTS: In RFL patients, positive APTT was 10.2%, APTT+PNP 3.6%, KCT 10.5%, and dRVVT 10.9%. In normal pregnancy, the corresponding figures were 12.8%, 3.1%, 10.8%, and 5.6%. Three positive tests occurred in 2.3% of RFL patients, including APTT+KCT 3.5%, APTT+dRVVT 3.9%, and KCT+dRVVT 4.1%. The corresponding figures for normal pregnancy were 1.6% for three positive tests, and 3.0%, 1.8%, 2.4%, respectively. The dRVVT was the only test that showed a rate of positive results almost double that seen in normal pregnancy. CONCLUSIONS: If only one or even two screening tests were performed, a significant number of LA positive cases would have been missed. This could make a difference to treating physicians as to the possible etiology and management of RFL. It is therefore advisable to routinely use the three tests (APTT, KCT and dRRVT) when screening for LA.