The urine pregnancy quick test kit is very practical for use at home, but in hospitals, blood tests are often more convenient. But when you want a hCG, you usually want it fast. Or the patient wants the answer fast. The lab is too slow. So, some have been using a few drops of blood on the urine pregnancy tests, and reporting good results on anecdotal basis. Here’s a study with 633 women enrolled, confirming that whole blood works just as well as urine on the quick pregnancy tests. Great trick for trauma patients and other emergency patients.

BACKGROUND: Point-of-care testing for rapid detection of pregnancy in women of reproductive age is common practice in the emergency department. Commercially available rapid human chorionic gonadotropin (hCG) immunoassays are validated for use with urine and serum, but not whole blood.
OBJECTIVES: We assessed the validity of using whole blood to detect pregnancy using a point-of-care hCG assay by comparing it to a laboratory quantitative serum hCG assay as the criterion standard.
METHODS: A convenience sample of female patients of reproductive age (18-51 years) submitted 5mL of whole blood, from which two drops were immediately applied to a point-of-care hCG kit, with results recorded at 10min. The remainder of each whole blood specimen was sent to the hospital laboratory for the criterion-standard quantitative serum hCG assay. The criterion standard for a positive pregnancy test was defined as quantitative serum hCG≥5 mIU/mL. Investigators performing the whole blood test and laboratory technicians performing the quantitative serum assay were blinded to one another’s results.
RESULTS: There were 633 patients enrolled, with a mean age of 30 years (± 7.7 years); 34% of the patients were pregnant. Overall, the whole blood pregnancy test was 95.8% sensitive (negative predictive value 97.9%), whereas the urine test was 95.3% sensitive (negative predictive value 97.6%); the specificity and positive predictive value of both tests was 100%.
CONCLUSION: Using a standard point-of-care qualitative hCG immunoassay kit, whole blood may be used for rapid detection of pregnancy with similar, or greater, accuracy than urine.

It was a pleasure to read a simple, but well made study on something as simple as a urine pregnancy quick test – and having it actually change my practice.

Substituting Whole Blood for Urine in a Bedside Pregnancy Test, J Emerg Med, 2011.

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