Vaginal versus oral E(2) administration: effects on endometrial thickness, uterine perfusion, and contractility.

Objective: To compare the effects of vaginal or oral E(2) administration on endometrial thickness, uterine perfusion, and contractility.

Design: Prospective, randomized, crossover study.

Setting: Assisted Reproduction Unit, Clamart, France.

Patient(s): Thirty-nine infertile women undergoing 78 E(2)/P cycles.

Intervention(s): Women received micronized 17beta-E(2), 2 mg/day orally (cycle days 1 to 28) and P, 300 mg/day vaginally (cycle days 15 to 28). After a menstrual cycle washout interval, women received a similar treatment except that 17beta-E(2) was administered vaginally.

Main Outcome Measure(s): Endometrial thickness, mean uterine artery pulsatility index, endometrial blood flow, and uterine contraction frequency assessed in ultrasound scans on cycle days 14 and 18.

Result(s): On day 14, the endometrium was thicker (8.7 +/- 0.6 vs. 7.1 +/- 0.3 mm, P< .0001), pulsatility index values were lower (2.4 +/- 0.1 vs. 3.0 +/- 0.2, P< .0002), and endometrial blood flow tended to be increased in the vaginal E(2) cycles as compared to the oral E(2) cycles. On day 18, similar differences remained. However, P-induced decrease in contraction frequency was slighter in vaginal E(2) cycles (33% vs. 18%, P< .0003).

Conclusion(s): Vaginal E(2) administration improves endometrial proliferation and uterine perfusion, presumably because of combined local and systemic effects, but may interfere with P-induced uterine relaxation.