![]() ![]() ![]() We describe these phenomena, present data from a review of false-negative uhCG tests in our ED, and discuss urine hCG POC testing and potential remedies for these false-negative results.Īmong approximately 87,000 annual visits to our ED in 2009, 11,760 urine hCG tests were performed. Recently, investigation of a number of false-negative urine POC tests among patients with late first-trimester pregnancies in our ED led to the postulation of a similar but distinct “hook-like” effect that can result in false-negative urine hCG testing at later stages of early pregnancy (Table 1) (6). In addition to familiar problems (incorrect reading time, insufficient/dilute urine, mislabeled specimens), false-negative results have been reported in urine-based POC qualitative hCG tests due to what is known as the “hook effect phenomenon” (6). Like all tests, POC uhCG tests have limitations. In addition to their accuracy, POC testing is also preferred in emergent settings due to its faster result times, with a mean time to result of 7.6 min, compared to 67.4 min for urine results from the laboratory (5). Compared to serum human chorionic gonadotropin (hCG) testing, urine hCG POC tests have been reported to achieve as high as 100% sensitivity and 99.2% specificity in a clinical setting, which resulted in a positive predictive value of 98.3% and a negative predictive value of nearly 100% (4). With their high level of reliability, POC tests have become a widely accepted, fast, and accurate method for determining pregnancy. Pregnancy tests in general usage include qualitative urine point-of-care (POC) tests in laboratories, clinics, and EDs over-the-counter (OTC) urine tests for consumer/layperson use and qualitative and quantitative serum tests. This has led to the emergency medicine dictum to check for pregnancy in all women of child-bearing age 1, 2, 3. These may include missed ectopic pregnancy (the leading cause of first-trimester pregnancy-related maternal death), administration of medications contraindicated in pregnancy, fetal radiation exposure, patient complaints, and lawsuits. Failure to detect pregnancy in the emergency department (ED) can have important consequences.
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