A radioreceptor assay for human chorionic gonadotropin in normal and abnormal pregnancies: a clinical evaluation.

The human chorionic gonadotropin-radioreceptor assay (hCG-RRA) offers a rapid and accurate method of diagnosing early and abnormal pregnancies. Such a method is described along with clinical correlations in 139 assays done on 122 patients with amenorrhea, normal pregnancies, infertility, trophoblastic disease, ectopic pregnancies, and missed or incomplete abortions. The accuracy of the test is correlated with weeks of amenorrhea, weeks after ovulation, and clinical diagnoses. The overall accuracy of the assay was 95%. Those performed more than 28 days after the last menstrual period had an accuracy of 96.4%. There were no errors in the diagnosis of eight ectopic pregnancies among 33 suspected cases. Three patients are described who had serial changes from negative to positive early in pregnancy, providing data on precise timing of a positive result. Cases of missed abortion sometimes demonstrate a positive hCG-RRA after documented fetal loss. Recommendations for the most appropriate use of the hCG-RRA are presented based on the clinical experience at one referral center during the period January, 1977, to June, 1978.