Abortions that fail.

In this study of 33,090 suction curettage abortions performed at less than or equal to 12 weeks' gestation, the rate of unrecognized failed abortions was 2.3 per 1000 abortions. Women with one or more prior pregnancies and those having an abortion at less than or equal to six weeks' gestation, particularly when small suction cannulae were used, were at higher risk for this complication (relative risks of 2.2, 2.9, and 11.1, respectively). Failures were also more likely when abortions were performed by resident physicians (relative risk of 2.2) and when they were performed on women with uterine anomalies (relative risk of 90.6). Physicians can minimize the risk of failed abortion by selecting an appropriate suction cannula size and by planning the optimal time to perform the abortion. Likewise, abortions performed either by residents or on women with uterine anomalies merit extra care.