Transient false-positive urine human chorionic gonadotropin in septic shock.

Point-of-care testing for urine human chorionic gonadotropin (hCG) allows rapid diagnosis of pregnancy and pregnancy-related disorders at the bedside. Urine hCG test kits use enzyme-linked immunosorbent assay technology and incorporate 2 types of monoclonal antibody in a sandwich structure. There have been case reports in a variety of disease states reporting interference with this method leading to false-positive results. We describe the case of a nonpregnant female presenting to the emergency department with septic shock secondary to severe colitis. Three sequential urine tests using the Clearview hCG test kit (Alere Limited, Stockport, United Kingdom) yielded positive results, whereas quantitative serum analysis was negative for hCG. This initial test result reverted to a true-negative result after 48 hours, suggesting the transient passage of an interferent into the urine at the time of initial testing. This may have been a molecule produced as part of the host inflammatory response or from bacterial synthesis of an interferent with hCG-like antigenic structure. It is important that clinicians are aware of the mechanisms and limitations of urine hCG testing and maintain a low threshold to undertake early serum hCG testing to confirm diagnosis.