Allan Cripps

Validation of the rosette inhibition test for the detection of early pregnancy in women

The authors validated use of the rosette inhibition test for the detection of early pregnancy factor (EPF) in human pregnancy, first by optimizing conditions for the assay, using known pregnant and nonpregnant sera, and second, by examining the performance of this assay in three clinical situations: a blind study involving coded first-trimester sera showed 80% correlation with pregnancy status; serial assay of EPF activity in sera collected from normal women attempting to conceive, correlated with human chorionic gonadotropin beta-subunit (beta-hCG) levels and pregnancy status; a longitudinal study of serial serum samples through two normal pregnancies showing the continued presence of EPF until the early third trimester in each case. It was concluded that with the rosette inhibition assay, consistent demonstration of a pregnancy-associated substance (EPF) could be obtained.

Early pregnancy factor as a monitor for fertilization in women wearing intrauterine devices.

Measurement of early pregnancy factor (EPF) by the rosette inhibition test was performed on serum samples from 14 women using intrauterine devices (IUDs). Serial blood samples taken during the luteal phase of 23 cycles demonstrated in six of the cycles a transient appearance of EPF during the 6- to 8-day period following ovulation. In contrast, no EPF activity was found in sera obtained from women in whom fertilization was prevented, either by sexual abstinence or tubal ligation. These observations support the postulate that the IUD functions by the prevention of implantation of the fertilized ovum, rather than by preventing fertilization.