A Case of a Negative Urine Pregnancy Test in a Multiple Gestation Pregnancy.

ABSTRACT

Urine pregnancy tests (UPTs) are a highly reliable method of detecting pregnancy, with reported 100% sensitivity and 99.2% specificity. This test relies on the detection of ß-human chorionic gonadotropin (ß-hCG) molecules in the urine through a two-site sandwich immunoassay. Although a nearly perfect test, it is common knowledge that this test can be falsely negative if performed too early in the pregnancy when urinary ß-hCG concentrations fall below detectable levels. Less commonly known is that the test may provide a false-negative result when urinary ß-hCG concentrations are extremely elevated, such as gestational trophoblastic disease or multiple gestations. Here, we present a case of a patient with a prior positive urine pregnancy test who presents with symptoms consistent with early pregnancy. Repeat testing resulted in a negative urine pregnancy test. Additional workup revealed significantly elevated serum quantitative ß-hCG and bedside ultrasound revealed multiple gestation intrauterine pregnancy. The patient ultimately delivered triplets by repeated caesarean section. It is important for physicians to understand and recognize the limitations of the urine pregnancy test in order to best facilitate care for patients who may have a false-negative pregnancy test result, as there are significant risks of improper patient management with a multiple gestation pregnancy or gestational trophoblastic disease.