Pregnancy Test, Urine

Five-minute immunoenzymetric assay: sensitivity − 20 mIU/mL (The test will normally become positive by the seventh day after menstruation fails to occur.) Proteinuria or hematuria may affect the performance of the test. Interpret specimens with these conditions cautiously. False-positive and false-negative results may also occur in specimens from individuals taking a variety of drugs. Urines from patients on methadone replacement therapy >100 mg/day have demonstrated a high incidence of false-positive reactions when using this test. If this condition is suspected and a positive test results, the test should be repeated using a different methodology. False-positives may also be reported with ectopic production of hCG and/or hCG-like substances by trophoblastic or nontrophoblastic neoplasms (eg, ovarian cysts, testicular tumors, carcinoma of the lung). Positive results from patients suspected to have elevated concentrations of pituitary gonadotropins such as LH should be interpreted with caution although cross reactivity is minimal. Positive tests are also found with various types of choriocarcinoma and hydatidiform mole. A complete abortion may result in a positive test for a week following the procedure.