The purpose of this study was to determine the accuracy of endometrial Pipelle (Unimar) biopsy to detect chorionic villi in suspected ectopic pregnancy.This was a blinded prospective trial that involved 32 women who were in stable condition with suspected ectopic pregnancy. Endometrial pipelle sampling was performed before uterine dilation and curettage. Pipelle and frozen section results were compared with final disease.Ten of 32 patients (31%) had chorionic villi that was consistent with a miscarriage; 22 of 32 patients (69%) had none detected. Pipelle biopsy had a sensitivity of 30% (95% CI, 6.7-65.2), a specificity of 100% (95% CI, 84.5-100), a positive predictive value of 100% (95% CI, 29.2-100), and a negative predictive value of 76% (95% CI, 56.5-87). Frozen section had a sensitivity of 87.5% (95% CI, 47.3-99.7), a specificity of 100% (95% CI, 83.1-100), a positive predictive value of 100% (95% CI, 59-100), and a negative predictive value of 95.3% (95% CI, 76.1-99.8).In patients with suspected ectopic pregnancy, Pipelle sampling is not a substitute for curettage because the sensitivity and predictive values are unacceptable.