A comparison of flexible and nonflexible plastic cannulae for performing first trimester abortion.

The safety and effectiveness of flexible and nonflexible plastic cannulae used in vacuum aspiration abortion for patients at 6 to 12 weeks' gestation were evaluated in a study of 1100 physically healthy women in Ljublijana, Yugoslavia. To minimize study biases, each type of cannulae was randomly assigned to 550 patients. To minimize evaluator bias, a second physician who was kept unaware of which cannula was used for particular patient was responsible for evaluating patients after the procedures. Both groups of patients were similar with respect to age, parity, marital status, formal education and gestational age. Higher rates of retained tissue and cannula obstruction were obtained with the flexible cannula. The two types of cannulae were not significantly different with respect to other criteria of evaluation.