Effect of normal rat serum injected into the uterus on fetal survival in the rat

We intended to use the rat model to study the effect of autoantibodies on implantation and fetal viability. However, we have since found an effect of normal rat serum on fetal resorption rate and fetal viability. The objective of this study was to determine the consistency of this effect. Wistar strain albino rats were used for injection of 150 μl normal rat serum into the lumen of uterine horn on days L₂–L₆. The other uterine horn, used as a control, was injected with 150 μl normal saline. Percent implantation, fetal resorption rate and fetal viability were determined following the intrauterine injection of normal rat serum as compared with normal saline. A significant increase in fetal resorption rate was observed following the injection of rat serum on days L₄ and L₅ (P = 0.003 and P = 0.001, respectively). A significant decrease in fetal viability was demonstrated following the injection of rat serum on day L₅ (P = 0.01). The rat can provide a suitable animal model for further studies.