Evaluation of histological and ultrastructural aspects of endometrium during treatment with gestrinone in women with amenorrhea or spotting

Nineteen patients with a laparoscopic diagnosis of endometriosis were treated with gestrinone at a dosage of 2.5 mg twice a week for 6 months. In 7 who reported spotting in the first 3 months, the dose was increased to 2.5 mg three times a week during the second trimester. An endometrial sample was obtained from each patient at the time of laparoscopy (basal) and at 3 and 6 months of treatment. Endometrial structure and ultrastructure were studied. Areas of hemorrhage and of loss of surface epithelium and a lesser degree of involution of the surface epithelium were observed in the 3-month samples of 7 patients with spotting, compared with 12 with amenorrhea. It is hypothesized that incomplete endometrial involution could be due to differences in gestrinone pharmacokinetics in individual patients, in the quality and/or quantity of endometrial cytosolic receptors for sex steroids, or in endocrine compensation to administration of the drug.