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

ABSTRACT

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. 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]. 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. 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