The Estes operation (transposition of one ovary to the uterine cavity): its results in the rabbit model.

Pregnancies have been reported after the Estes procedure (EP). These results have not been duplicated in modern attempts. The recent report of intrauterine fertilization in humans gives support to the feasibility of this procedure as a possible alternative to in vitro fertilization. An animal model is needed to evaluate the outcome of this operation. Consequently, 14 mature New Zealand white rabbits had one ovary placed in the uterine cavity after contralateral oophorectomy and bilateral salpingectomy. One month later, the animals were mated with a fertile buck. Fourteen to 16 days after that, the outcome was evaluated. Twenty-five to 75% of the ovarian surface was exposed to the uterine lumen, and no evidence of ovulation or implantation was found. The lack of pregnancies was attributed to an ovulatory dysfunction. Anovulation after the EP may also occur in the clinical situation, as suggested by one histologic study. The ovulatory function of these patients has not been characterized in the literature. Documentation of a successful intrauterine fertilization with delivery of a term baby supports the theoretical feasibility of the EP; however, anovulation incurred by our procedure appears to be the major drawback.