New immunochemical method for rapid detection of human choriogonadotropin in urine

We describe a visual assay for rapid detection of choriogonadotropin (hGC) in human urine, and evaluate a pregnancy test kit that is based on this assay and designed for use by the general public. The assay involves the formation of an antibody-antigen complex between the anti-hGC antibodies coated on the membrane protein of Staphylococcus aureus bacteria, prestained with hematoxylin, and the hGC concentrated on a column of Sepharose-concanavalin A. The test was calibrated to detect as little hGC as 0.9 (SD 0.15) int. unit/mL. The kit, clinically tested with 448 urine samples, was 99.6% accurate. Simple to perform, the test gives highly reliable results as early as five days after the missed menstrual period.