Lupus anticoagulant (LA) in pregnant women with history of recurrent fetal loss

The frequency of LA in 50 women with intact pregnancy, age range 26 to 39 years, but with past history of at least 2 lost pregnancies, was determined using coagulation-based assays. Most (68%) of the pregnant women were in the first trimester. Venous blood (4.5 mL) carefully collected from each of the subjects and also the controls (normal relative donors) was put in 0.5 mL of 3.8% citrate (ratio 9:1). The blood was quickly centrifuged at 1500 g; platelet-poor plasma was separated and frozen at -30°C until analyzed. The control plasma was pooled and dispensed in 2 mL aliquots. Partial thromboplastin time with kaolin (PTT(k)) (against the control samples for comparison) and kaolin clotting time (KCT) were determined on each of the test samples using standard laboratory procedures. Prolonged PTT(k) was obtained in 36 patients (72%). KCT was obtained through mixtures of patients' plasma with pooled control plasma (P:C) at 100:0; 0.8:0.2; 0.6:0.4; 0.5:0.5; 0.4:0.6; 0.2:0.8; 0:100; and lin-lin graph paper was used to plot out each of these dilutions against their respective clotting time in seconds. The interpreted graph showed that 12 (24%) had LA, while 3 (6%) had LA with cofactor. This high frequency necessitates regular screening for LA in pregnant women with a history of recurrent fetal loss at any gestational age.