Sensitivity and specificity of a urinary screening test used in an emergency setting to detect abnormal first trimester pregnancies.

OBJECTIVE: To evaluate the performance of a commercial urinary test to screen for abnormal first trimester pregnancies in women presenting to an emergency room.

STUDY DESIGN: In this prospective observational cohort, women with a confirmed first trimester pregnancy (gestational age <12 weeks) provided a urine sample for diagnosing the viability of their gestation. Pregnancy viability and location testing were confirmed by ultrasound and/or laparoscopy.

RESULTS: From 815 eligible patients for the study, 12 were excluded for not having a confirmed pregnancy (n = 6) or were lost to follow-up (n = 6). A total of 803 patients underwent testing and completed follow-up. The pretest probability of an abnormal pregnancy was 44% (9% for ectopic pregnancy and 35% for miscarriage). The test had the following parameters to identify an abnormal first-trimester pregnancy (sensitivity, 13%; 95% confidence interval [CI], 10-17; specificity, 82%; 95% CI, 78-86; positive predictive value, 36; 95% CI, 28-46; negative predictive value, 54; 95% CI, 50-58; accuracy, 47%; positive likelihood ratio, 0.74; 95% CI, 0.53-1.03; negative likelihood ratio, 1.06; 95% CI, 1-1.12). The reproducibility of the test in our study was high (kappa index between readers, 0.89; 95% CI, 0.77-1).

CONCLUSION: In our emergency setting, we were not able to confirm that the commercial test is adequate to detect or exclude an abnormal first-trimester pregnancy.