Accuracy of a semi-quantitative urine pregnancy test compared to serum beta-hCG measurement: a possible screening tool for ongoing pregnancy after medication abortion.

PURPOSE: Medication abortion protocols commonly rely on ultrasound or serum hCG measurement to confirm completion. In order to explore the use of a urine-based test to screen for ongoing pregnancy, we compared the diagnostic accuracy of a recently developed semi-quantitative urine pregnancy test to serum beta-hCG testing.
METHODS: We evaluated the urine test with 97 women in early pregnancy at a hospital and private clinic in Mexico City. The results of the urine test (hCG level > or <1000 IU/L) were correlated with those of a serum quantitative beta-hCG immunoradiometric assay.
RESULTS: The sensitivity of the urine test to identify individuals with a serum beta-hCG level >1000 IU/L was 88.6% (95% CI 74.6- 95.7%), and its specificity was 71.7% (95% CI 57.4-82.8%).
CONCLUSION: The reasonably high sensitivity of this urine test suggests it might be useful as a screening test to detect ongoing pregnancy after medication abortion. Future research should evaluate its utility in clinical follow-up protocols.