Accuracy of home pregnancy tests at the time of missed menses

Objective The purpose of this study was to investigate the validity of home pregnancy tests (HPTs) around the time of the missed menses. Study design Levels of human chorionic gonadotropin (hCG) were determined in urine around the time of the missed menses, and 5th and 95th centiles were calculated. In a blind study evaluating 18 brands of HPTs, each was tested six times with five concentrations of hCG, 0 to 100 mIU/mL. Sensitivity was defined as the concentration at which six of six brands gave positive results, at the suggested reading time or at an extended time. Results It was estimated that a sensitivity of 12.5 mIU/mL was needed to detect 95% of pregnancies at the time of missing menses. Only 1 of 18 HPTs had this sensitivity. If faintly discernible results considered, 2 of 18 brands gave false-positive or invalid results. Clear positive results were given by only 44% of the brands at 100 mIU/mL hCG. If one accepted faintly discernible and extended reading times, all brands responded at 100 mIU/mL. A test with 100 mIU/mL sensitivity would detect approximately 16% of pregnancies at the time of missed menses. Conclusion The utility of HPTs is questioned. Clinicians need to be aware of the limitations of current HPT brands