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

By Daniel Grossman, Karla Berdichevsky, Fernando Larrea & Jorge Beltrand

Abstract

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 semiquantitative urine pregnancy test to serum β-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 theurine test (hCG level N or b1000 IU/L) were correlated with those of a serum quantitative β-hCG immunoradiometric assay.

Results: The sensitivity of the urine test to identify individuals with a serum β-hCG level N1000 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.
© 2007 Elsevier Inc. All rights reserved.

Keywords: Sensitivity and specificity; Urine pregnancy test; Abortion; hCG