Establishing early pregnancy levels of serum progesterone in functionally agonadal women using polysiloxane vaginal rings and cylinders.

Using a polysiloxane cylinder impregnated with crystalline progesterone (P4), combined with a 17 beta-oestradiol (E2) and P4 vaginal ring, we produced first trimester pregnancy levels of serum P4 in six functionally agonadal women scheduled for transfer of donated embryos. With this 4 g P4 cylinder worn from cycle day 15 to day 30, overall mean serum P4 concentrations were 15.03 +/- 1.56 ng/ml, with a mean peak level of 21.34 +/- 1.85 ng/ml. These levels were significantly higher than those obtained by us previously in five subjects using a 2 g P4 cylinder [P = 0.007]. The cylinder produced minor but significant complications including small vulvovaginal lacerations, difficulty in removing the device, and vaginal discharge. We conclude that the steroid impregnated polysiloxane vaginal ring and cylinder system provides: continuous and sustained hormone release, and levels of serum P4 in the normal range for early pregnancy. Side effects however, may limit its clinical usefulness.