Rapid hCG-specific radioimmunoassay for menstrual aspiration.

Fifty-one women with missed periods ranging from 5 to 14 days who suspected a pregnancy underwent an aspiration curettage with a flexible soft-tipped cannula attached to a Karman-type syringe. Sera from these women were measured 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. The sensitivity and specificity of this assay insured detection of bCG with 100% accuracy at the time of the missed period. Of the 51 women, 33 (64.7%) were found to have hCG in their serum, and 29 (56.8%) had histologic evidence diagnostic of pregnancy.