A contemporary approach to suspected ectopic pregnancy with use of quantitative and qualitative assays for the β-subunit of human chorionic gonadotropin and sonography

Abstract

Although assays for the beta-subunit of human chorionic gonadotropin (beta-hCG) and ultrasonography have become popular diagnostic aids in the approach to patients with a suspected ectopic pregnancy, their true utility has not been clearly defined; in fact, the beta-hCG assay is so sensitive that proper clinical interpretation is sometimes difficult. A recent study describing a "discriminatory zone" (beta-hCG level of 6000 to 6500 mIU/ml), which correlates beta-hCG levels with appearance of a gestational sac on ultrasound scans, has been reported to be of diagnostic benefit. A prospective study of 103 women with suspected ectopic pregnancy was undertaken utilizing an algorithm which included beta-hCG assays (quantitative as well as qualitative) and ultrasonography. Seventy-three patients were found not to be pregnant, and seven had a normal pregnancy, 14 patients ultimately had a spontaneous abortion, and seven ectopic pregnancies were identified. The following conclusions were drawn: (1) a qualitative beta-hCG assay with a sensitivity of 25 mIU/ml is an effective test in screening for ectopic pregnancies; (2) the concept of a "discriminatory zone" is valid but not of frequent clinical utility, since most patients suspected of having an ectopic gestation have beta-hCG levels below this zone; (3) serial monitoring of beta-hCG values is an important diagnostic aid; (4) culdocentesis is still an important contemporary diagnostic test for the patient suspected of ectopic pregnancy.