To evaluate the utility of pipelle endometrial sampling as a diagnostic tool in the evaluation of abnormal first trimester gestations. Thirty-one women with abnormal first trimester pregnancies defined as gestations with abnormally rising or falling quantitative human chorionic gonadotropin (β-hCG) levels and ultrasound findings consistent with a nonviable or ectopic pregnancy were prospectively evaluated. Endometrial pipelle sampling was performed on each patient in a standardized fashion immediately before curettage and evaluated as a fixed, permanent specimen to assess for the presence of either chorionic villi, trophoblastic or fetal tissue. The sensitivity, specificity, positive predictive value, and negative predictive value for endometrial biopsy were 70.1%, 100%, 100%, and 33.3%, respectively. For curettage, the sensitivity, specificity, positive predictive value, and negative predictive value were 88.9%, 100%, 100%, and 57.1%, respectively. Curettage's overall sensitivity is superior to endometrial biopsy in detecting the presence of intrauterine products of conception in early abnormal pregnancies. However, in some clinical situations where the diagnosis of ectopic pregnancy is in question, particularly if the β-hCG is ≤ 2,000 mIU/mL, endometrial pipelle biopsy could be a useful tool in the evaluation algorithm.