Limitations of qualitative serum beta-HCG assays in the diagnosis of ectopic pregnancy.
Seventy-four patients had ectopic pregnancies proven by surgery. Three of them had a serum beta-HCG test for pregnancy that was reported as negative (less than 25-35 mIU/ml). We sought a threshold for positive in the serum beta-HCG test that would maximize its usefulness in diagnosing ectopic pregnancy. Sera from 52 of the patients were available for reanalysis. Quantitative values of beta-HCG were determined. Lowering the threshold for positive from 25-35 to 10 mIU/ml might increase the test's sensitivity without sacrificing specificity but would still not ensure detection of all ectopic pregnancies. Of 445 cases of ectopic pregnancy described in the literature, 6 had serum beta-HCG values reported as negative. In the published reports and in our own cases, clinical histories and histologies indicated that a nonviable ectopic pregnancy can be expected to have an associated serum concentration of beta-HCG that may be below the sensitivity of detection even with current, commercially available quantitative tests.
D000328:Adult; D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D005260:Female; D006801:Humans; D010535:Laparoscopy; D010446:Peptide Fragments / Q000097:blood*; D011247:Pregnancy; D011259:Pregnancy Tests, Immunologic; D011271:Pregnancy, Ectopic / Q000175:diagnosis*
D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments