Rapid hCG-specific radioimmunoassay for menstrual aspiration.

Aspiration curettage was performed on 51 women who suspected pregnancy and had missed periods from 5 to 14 days. Sera obtained from the patients were analyzed for human chorionic gonadotropin (HCG) by a rapid 2-hour solid-phase radioimmunoassay using an antibody with a specificity for the beta subunit of HCG. 33 of the women (64.7%) were found to have serum values ranging from 8 mIU/m1 to 3997 mIU/m1. 29 of the women (56.8%) showed histologic evidence of pregnancy. Generally more women had HCG in their serum as the number of days following the missed period increased. The test can detect HCG with 100% accuracy at the time of the missed period.