A comparison of metal and plastic cannulae for performing vacuum.

A comparative study was conducted to evaluate the efficacy of a metal or flexible plastic 8 mm cannula for artificial abortion by vacuum aspiration for patients at six to 10 weeks' gestation. Complication rates, amounts of retained tissue (obtained with a curette check), frequencies of cannula obstructions and procedure times were used as criteria for determining the efficacy of the two types of cannulae. Two physicians participated in the study: one was responsible for the preliminary examination and performance of the abortion, and the other physician, who was kept unaware of the type of cannula used, was responsible for patient care after completions of the abortion to the time of the follow-up visit. Paracervical block anesthesia was used in all cases. Differences in complication rates (controlled for gestational age) between groups of subjects aborted with either the metal or flexible plastic cannula were not significantly different (p less than .05). For both patient groups shock was the most frequently reported immediate complication (2.7% in the metal cannula group, 4,7% in the flexible plastic cannula group), and leukorrhea was the most frequently reported complication at the time of follow-up (3.3% metal, 5.3% flexible plastic). Amounts of retained tissue and frequency of cannulae obstruction were similar for both groups. Procedure times were also similar for both groups (means of 5.7 minutes and 5.5 minutes, respectively, for procedures performed with the metal and flexible plastic cannulae).