Ultrasonographic measurement of endometrial thickness during hormonal replacement therapy in postmenopausal women.

The objective of this study was to measure endometrial thickness by transvaginal ultrasonography during two regimens of hormonal replacement therapy (HRT) in postmenopausal women and to compare these data with endometrial histology. Transvaginal ultrasonographic evaluation of endometrial thickness and endometrial biopsy were performed in 80 postmenopausal women before and after 6 months of HRT (between the 24th and the 28th day of the cycle). The group was randomized so that 40 women (Group A) were treated with a continuous sequential regimen consisting of 5 micrograms/day of estradiol continuously and 5 mg/day of medrogestone from the 17th to the 28th day of the cycle; and 40 women (Group B) were given continuous administration of 50 micrograms/day estradiol and 5 mg/day medrogestone. Prior to therapy, there was no significant difference in mean endometrial thickness between the groups. After 6 months of therapy, endometrial thickness was significantly increased in comparison with basal values in both groups. The mean value was significantly higher (p < 0.001) in Group A (8.5 +/- 3.7 mm) than in Group B (3.6 +/- 1.3 mm). In Group A, endometrial thickness was < or = 4 mm in 16.7% of patients and < or = 8 mm in 69.5% of patients. In Group B, 91% of patients had an endometrium of < or = 4 mm. In both groups, the thickness of the atrophic endometrium was less than that of the other histological types of endometrium (4.1 +/- 0.3 mm for Group A and 3.5 +/- 1.2 mm for Group B). In Group A, the difference in mean endometrial thickness between the proliferative and secretory endometrium was not statistically significant. In both groups, the transvaginal ultrasonographic measurement of endometrial thickness of < or = 4 mm had a high sensitivity for detecting atrophic endometrium (83.3% for Group A and 93.7% for Group B).