The use of a radioreceptorassay of human chorionic gonadotropin for the diagnosis and management of ectopic pregnancy

Abstract

The radioreceptorassay of human chorionic gonadotropin (hCG), with a sensitivity of 50 pg or 3 mIU/ml of plasma, has provided almost 100% reliability in detecting pregnancy after the first missed cycle. This test may be performed within 1 hour and is ideally suited to the clinical detection of ectopic pregnancy, especially in patients who require immediate surgical intervention. Thirteen patients with suspected ectopic pregnancy were evaluated by the radioreceptorassay, one of whom was followed with four separate determinations. The results of the assay were subsequently compared with those of hemagglutination pregnancy tests, clinical symptoms, and pathologic findings. All of the patients were diagnosed accurately by the radioreceptorassay, even when hemagglutination tests yielded a false indication of pregnancy. By this assay, the hCG levels during ectopic pregnancies are generally lower than those found during a normal intrauterine pregnancy; in addition, pregnancy may be detected much earlier (prior to the rupture) than is possible by hemagglutination tests. Furthermore, the diagnosis of ectopic pregnancy may be excluded for patients admitted to the hospital with acute abdominal emergencies.

PIP: 13 patietns whose last menstrual period occurred 23-76 days before admission were hospitalized for a suspected ectopic pregnancy and were evaluated by both a radioreceptorassay (RRA) of human chorionic gonadotropin (HCG) and conventional hemagglutination or latex agglutination tests. RRA correctly differentiated pregnancy from nonpregnancy in all cases, whereas the hemagglutination tests yielded 1 false positive and 7 false negatives. The RRA can detect ectopic pregnancy because HCG levels are lower than for a normal intrauterine pregnancy. RRA can be performed in an hour, is 500 times more sensitive than the hemagglutination tests, and is almost 100% reliable within a month of the 1st missed period. The test could eliminate the incorrect diagnosis of pregnancy, helping to avoid either unnecessary or delayed surgical procedures.