RESUMO
There are various successful protocols for artificial endometrial preparation, comprising induction of endometrial proliferation with estrogens and secretory transformation with progestins. The aim of this prospective randomized study was to evaluate a simplified approach for endometrial preparation, comparing two constant doses of oral estradiol combined with a novel low-dose vaginal natural progesterone preparation (100 mg Endometrin tablets). Twenty-nine patients were enrolled in the study and divided randomly into two groups. Both groups received oral estradiol tablets from the beginning of menstruation, group A (15 patients) receiving 4 mg/day divided into two doses of 2 mg each, and group B (14 patients) receiving 6 mg/day divided into three doses. Serum estradiol and progesterone and sonographic thickness of the endometrium were measured on the 1st day of menstruation and on the 6th, 11th, 16th and 21st days of the artificial cycle. Following the first 12 days of estradiol priming, with an endometrial thickness of > or = 8 mm, Endometrin vaginal tablets 100 mg were added twice a day for 10 days. On the 21st cycle day, an endometrial biopsy was taken from all patients using Pipelle. In all 29 patients, appropriate changes in estradiol, progesterone and endometrial thickness were observed. Estradiol levels were significantly higher in the 6 mg/day group on days 6 and 11, but no significant difference was noted in serum progesterone level and endometrial thickess between groups. Histological evaluation of endometrial biopsies, on the 21st day, revealed adequate late-secretory endometrium in 14/15 (93.3%) patients of group A and in 13/14 (92.9%) patients of group B. In conclusion, our results demonstrate that an appropriate endometrial secretory transformation may be induced using an economical regimen of fixed low-dose oral estradiol (4 mg/day) and low-dose vaginal progesterone tablets (Endometrin 100 mg twice daily).