Patient history and physician suspicion accurately exclude pregnancy.

Objectives: Reliance upon patient assessment in excluding pregnancy is questionable. Physicians are encouraged to obtain pregnancy tests in all women of childbearing age. We affirmed the accuracy of women and their physicians in predicting pregnancy.

Methods: This was a prospective, observational study performed in a suburban academic emergency department on adult women with an ordered pregnancy test. A standardized gynecologic history was obtained by trained research assistants. Subjects estimated their likelihood of pregnancy as impossible, possible, or definite. Emergency department physicians estimated the likelihood of pregnancy as high, moderate, or low. All women had either a serum or urine β-human chorionic antigen. The diagnostic characteristics of patient and physician predictions of pregnancy were calculated with 95% confidence intervals (CIs).

Results: We enrolled 377 subjects. Median age was 29 (interquartile range, 22-37) years. Twelve percent of the women were pregnant. Women's estimates of pregnancy were as follows: impossible, 64.7%; possible, 22.5%; and definite, 12.7%. The pregnancy rates among women with estimates of impossible, possible, and definite were 0% (95% CI, 0%-1.5%), 4.7% (95% CI, 1.9%-11.5%), and 89.6% (95% CI, 77.8%-95.5%) (P < .001). Physicians' suspicions of pregnancy were high (13.7%), moderate (11.3%), and low (75.1%). The rate of pregnancy among low, moderate, and high physician suspicion groups were 0% (95% CI, 0%-1.4%), 9.5% (95% CI, 3.8%-22%), and 84.3% (95% CI, 72%-92%) (P < .001).

Conclusions: There were no pregnancies among women who estimated pregnancy as impossible or whose physicians thought that the likelihood of pregnancy was low. Routine pregnancy testing before radiological imaging and medication administration may not be required in adult women of childbearing age.