Urine Pregnancy Testing in Two Women with Cancer

Abstract

Questions1. What are the most striking clinical and laboratory findingsin these patients?2. Why is it important to assess pregnancy status?3. What are some of the causes of false-positive serum andurine pregnancy tests?4. How would you rule out human or technical error as a possiblecause of a false-positive or -negative urine pregnancy test?5. What can cause discordances between urine and serum hCGtest results?6. What is the most likely diagnosis for these patients?7. What is the clinical significance of a false-positive urinepregnancy test?8. Are serum hCG tests unaffected by factors that can causefalse-positive test results?Possible Answers1. The most striking laboratory findings in both of thesepatients was a positive urine pregnancy test in patients who,based on their medical history (data not shown), were not ex-pected to have a positive urine hCG pregnancy test.2. Determination of pregnancy status is important in thework-up of a woman presenting with vaginal bleeding or lowerabdominal pain. Women with these symptoms should bescreened for pregnancy using a urine pregnancy test, especiallyprior to undergoing an x-ray procedure. Clinical decisions re-garding additional diagnostic testing should be based on the re-sults of the urine pregnancy test and knowledge of thoseconditions that can cause false-positive screening tests for humanchorionic gonadotropin (hCG) in urine and serum, includingthe presence of serum human anti-mouse antibodies (HAMA)and diseases (eg, colon or cervical cancer) associated with excre-tion of hCG into the urine.3. A number of preanalytical conditions, other than preg-nancy, including trophoblastic disease and certain non-trophoblastic neoplasms (eg, testicular tumors, prostate cancer,breast cancer, and lung cancer), can cause elevated serum levelsof hCG that are then excreted into the urine.