Uterine perfusion and endometrial thickness in postmenopausal women on long-term continuous combined estrogen and progestogen replacement.

We assessed the resistance index (RI) and pulsatility index (PI), peak and average systolic velocities in uterine, arcuate and radial arteries, and endometrial thickness (ET) by transvaginal B mode and color Doppler sonography in patients on continuous combined hormonal replacement therapy (HRT) and controls. HRT consisted of 2 mg estradiol, 1 mg estriol and 1 mg norethisterone acetate daily (n = 33) compared to controls, who received none of these (n = 21). Age was 61 +/- 6 and 59 +/- 9 years (mean +/- standard deviation) in the HRT and control groups, respectively. The duration of HRT was 5 +/- 2 years, with a minimum of 1 year. We found that the uterine RI and, to a lesser extent, the uterine PI were significantly lower and the radial peak systolic velocities were significantly higher in the HRT group compared to controls. The highest uterine PI values were measured in controls with the shortest life-time exposure to endogenous estrogens, i.e. late menarcheal age or early menopause. The endometrial thickness of 2.8 +/- 1.8 mm in the HRT group was not significantly different from that in the controls (4.2 +/- 5.6 mm). In conclusion, the alteration in blood flow parameters demonstrated in this study would suggest that the long-term use of continuous oral estradiol 2 mg, estriol 1 mg and norethisterone acetate 1 mg daily is associated with a slight increase of flow in the uterine arteries compared to controls matched for (postmenopausal) age. Endometrial thickness does not increase with duration of use of continuous combined HRT.