Use of the radioreceptor assay for human chorionic gonadotropin in the diagnosis of ectopic pregnancy.

Since unrecognized ectopic pregnancy is a potentially lethal condition, there is a need for an accurate, rapid, sensitive and specific method for measuring low levels of human chorionic gonadotropin that may be observed in ectopic pregnancy. The Biocept-G test is a commercial modification of the radioreceptor assay for human chorionic gonadotropin. The test is performed in one hour and has a sensitivity of 200 milliinternational units of human chorionic gonadotropin per milliliter of serum. This study consisted of 15 patients with proved tubal ectopic pregnancies who were evaluated with the Biocept-G assay. All of the patients had a positive test result. By comparison, the two hour urine tube test result was positive in only eight and negative in seven patients. The two minute urine slide test result was positive in only six and negative in nine patients. The Biocept-G test was found to be simple to perform, quick and reliable, and the cost was comparable with that of the less accurate immunoassays. With the advent of the radioreceptor assay for human chorionic gonadotropin and the radioimmunoassays for the beta subunit of human chorionic gonadotropin, the presence of a positive pregnancy test result may be the most reliable diagnostic aid in helping to recognize early ectopic pregnancy.