Abstract

Objectives: Pregnancy tests are often performed routinely for female emergency department (ED) patients of reproductive age. One major reason is a perception that patients are unreliable in predicting their own pregnancy status. We hypothesised that patients could reliably predict that they were not pregnant.

Methods: The study used a prospective cohort design, in an urban academic ED, from January 19 to May 19, 2004. All patients for whom a pregnancy test was ordered were asked about their sexual history as well as two additional questions: “Do you think you might be pregnant?” and “Is there any chance you could be pregnant?” Patients with already documented pregnancies were excluded.

Results: A total of 474 patients had pregnancy tests performed that met inclusion criteria. Eleven (2.3%) tests were positive. Among patients who answered no to both questions (337), one test (0.3%) was positive (negative predictive value (NPV) 99.7%, likelihood ratio (LR) 0.13 (95% CI, 0.02 to 0.82)). The other historical factor with a high NPV (100%) was not being sexually active (LR not calculable). All pregnancies occurred in patients with gastrointestinal or genitourinary as the chief complaint: this comprised only 56% of the presentations for which tests were ordered.

Conclusion: Sexual history and self assessment can be used as a highly effective predictor of a patient not being pregnant. Given the risks of missed pregnancy in the ED, and low monetary and time cost of pregnancy tests, frequent testing is still recommended in most instances.