Endometrial changes according to hormone replacement therapy schedule

The purpose of this study was to assess differences in endometrial thickness, ultrasonographic characteristics, and histological and bleeding patterns in two groups of women according to the type and length of hormone replacement therapy (HRT) administered.

Twenty-seven women were divided into two groups. Group I received oral conjugated estrogens 0.625 mg/day for 21 days, plus chlormadinone 2 mg the last 12 days, for a median length of 6.5 months' time. Group II received oral conjugated estrogens 0.625 mg/day plus chlormadinone 1 mg/day, both continuous and uninterrupted (n = 13), for a median length of 3 months' time. Using transvaginal ultrasound, endometrial thickness, refringence, and the presence of liquid in the uterine cavity were analyzed. An endometrial biopsy was performed the same day and the histological and bleeding patterns were described. Statistical analysis was performed with Mann-Whitney U test, Fisher's exact test, and Spearman correlation coefficient.

Results of these tests showed that liquid in the uterine cavity and secretory endometrium were frequently found in those with sequential schedule (Group I); regular uterine bleeding was also frequent in this group. Negative correlation coefficients were found in this group between duration of HRT and endometrial thickness and uterine bleeding patterns, and in the continuous schedule group, between the duration of HRT and uterine bleeding pattern.

We conclude that endometrial and ultrasonographic changes depend on the type of HRT schedule and the duration of therapy.