Polyurethane contraceptive vaginal sponge: product modifications resulting from user experience.

A preliminary study of a new contraceptive vaginal sponge containing the spermicide nonoxynol -9 (N-9), was undertaken to assess acceptability of the method among a group of sexually active volunteers in Mexico City. Numerous modifications of the product and its packaging resulted from user experience and feedback to the physicians and bioengineers conducting the study. Although determining efficacy of the sponge was not an objective, it quickly became clear that spermicide is a crucial component of the intravaginal sponge contraceptive system; a high incidence of pregnancies led us to increase the spermicide level from 10% to 20%, then to the current 30% of dry sponge weight, or about 1.0 gram per sponge. (It should be noted that the high pregnancy rates were consistent with our experience using other vaginal contraceptive methods in the same clinic population). This initial evaluation of the contraceptive sponge has resulted in significant modification which should increase its acceptability to a small but important group of contracepting women. The sponge is currently being evaluated by the International Fertility Research Program (IFRP) in multicentered comparative clinical trials to determine use-effectiveness and acceptability in various cultures.