Fetal survival in the rat as affected by intrauterine injection of serum containing antiphospholipid antibodies

Problem: We wanted to study and examine whether the detrimental effect of antiphospholipid antibodies on gestation is locally derived. Therefore, we established an experimental rat model, enabling to study the intrauterine effect of serum, containing antiphospholipid antibodies, in vivo. Methods: Sera were obtained from five women, having anticardiolipin antibody and lupus anticoagulant, and presenting with antiphospholipid antibody syndrome. Pooled serum of 150 μL was injected into unilateral uterine horn of each rat on days L₂-L₇ of rat pregnancy. The contralateral uterine horn was used for injection of 150 μL normal serum or physiologic saline as a control. The rats were sacrificed on day L₁₄, and the uterus of each rat was inspected for the presence of live and resorbed fetuses. Results: A significant effect on fetal resorption and viability was observed following the intrauterine injection of antiphospholipid positive serum (APL positive serum), as compared with the intrauterine injection of normal serum or saline. A significant increase in fetal resorption rate and decrease in fetal viability was noted following the injection of APL positive serum on day L₆ (P = 0.005 and 0.004, respectively) and day L₇ (P = 0.003 and 0.003, respectively) as compared with normal serum. A comparison with the contralateral injection of saline demonstrated a significant effect of the APL positive serum also following the intrauterine injection on days L₃ and L₅. Conclusions: The current study provides an experimental rat model, which can be employed to study the local intrauterine effect of APL positive serum on pregnancy outcome and to further assess the efficacy of various treatment modalities.