Objective: To evaluate the endometrial thickness in different periods of a continuous-sequential HRT regimen and to correlate the ultrasonographic findings with the histological patterns.
Methods: The study was structured in two phases. In the 1st phase, 37 postmenopausal women (group A) treated by at least 6 months with a conventional continuous-sequential hormonal replacement therapy (cs-HRT) regimen were enrolled. In all patients, the endometrial thickness was measured at the 7th, 14th, 21st and 25th day of the cycle using transvaginal ultrasonography (TV-USG). In the 2nd phase of the study, other 41 postmenopausal women (group B) were enrolled and treated with the same sc-HRT regimen. At entry and after six cycles of cs-HRT, an endometrial biopsy was performed. The endometrial pattern was related with endometrial thickness. Either the evaluations were performed immediately after progestogen withdrawal bleeding, as showed by 1st phase results.
Results: The results of the 1st phase of the study showed a mean endometrial thickness significantly lower at 7th day of the cycle compared to 14th, 21st and 25th day (4.3+/-1.2 versus 6.6+/-2.9, 7.8+/-4.2 and 7.4+/-4.6 mm+/-SD, respectively). After six cycles of cs-HRT (2nd phase of the study), the mean endometrial thickness was significantly increased in comparison with basal values (4.2+/-1.5 versus 2.8+/-1.2 mm+/-SD; P<0.05). Endometrial biopsies showed 13 cases (39.4%) of atrophy and 20 cases (60.6%) of proliferative endometrium. Mean endometrial thickness in case of atrophy was lower than in presence of a proliferative endometrium (3.7+/-1.2 versus 4.4+/-1.4 mm+/-SD; not significant). Endometrial thickness was <4 mm in 16 cases (11 of atrophic and five of proliferative endometrium), between 4 and 5 mm in 15 cases (13 of proliferative and two of atrophic endometrium) and between 5 and 6 mm in two cases (either case of proliferative endometrium).
Conclusions: The best timing for monitoring endometrial thickness during cs-HRT regimens is the period immediately after withdrawal bleeding improving the reliability of the ultrasonographic exam to identify endometrial pathologies.