Performance of a quick pregnancy test on whole blood in early pregnancy units: a prospective cohort study

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Abstract

Objective

To assess the diagnostic performance of the NG-Test human chorionic gonadotropin (hCG) WB, which is a new point-of-care (POC) hCG whole-blood test.

Materials and methods

This prospective study included women consulted in early pregnancy units for vaginal bleeding and/or pelvic pain with unknown pregnancy status after medical consultation including a pelvic ultrasound scan. A new POC test (the NG-Test hCG WB) and the usual laboratory serum test (considered the gold standard) were performed in patients. The results were interpreted in a blinded manner. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the NG-Test hCG WB.

Results

During the study period, 200 patients were included. The pregnancy rate was 17%. For the laboratory test, with a 5 UI/l hCG positivity threshold, the sensitivity, specificity, PPV, NPV, and Youden index of the NG-Test hCG WB were 89.7, 100, 100, 97.9, and 0.90%, respectively. Considering a 10 UI/l hCG positivity threshold, test sensitivity, specificity, PPV, NPV, and Youden index were 96.3, 100, 100, 99.3, and 0.96%, respectively. False-negative cases were either extremely brief pregnancies or residual hCG after miscarriage. The result was obtained within 5 min with the NG-Test hCG WB versus 90±31 min with the laboratory test. It was easy to use.

Conclusion

The NG-Test hCG WB showed a high sensitivity, specificity, PPV, and NPV. Its use as triage in the case of a negative pelvic ultrasound exam is a potential strategy to improve patient flow, with an average time saving of 85 min.

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