Ultrarapid and highly sensitive time-resolved fluoroimmunometric assay for chorionic gonadotropin.

A fluoroimmunoassay for chorionic gonadotropin (hCG) was used to detect pregnancy-related disorders in 130 patients attending an outpatient ward because of lower abdominal pain or uterine bleeding. The test uses two monoclonal antibodies and is very rapid (20 min) and highly sensitive (2 IU/l). The number of positive results depends on the selection of cut-off level. All women with ectopic pregnancies were positive at a cut-off level of 10 IU/l, whereas 95% were positive at 25 IU/l. The lower cut-off level was more effective in detecting pregnancies, but it gave more apparently false-positive results and occasionally created problems in clinical management. These difficulties were overcome by serial quantitative estimations of hCG. These results give promise of an effective and simple side-room test for hCG which does not depend on the working hours of a laboratory equipped for handling radioisotopes.