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Hormonal profile and endometrial morphology in letrozole-controlled ovarian hyperstimulation in ovulatory infertile patients.

Cortínez A, De Carvalho I, Vantman D, Gabler F, Iñiguez G, Vega M

Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile. acortinez@ns.hospital.uchile.cl

OBJECTIVE: To evaluate the clinical response and endometrial morphology during the implantation window on ovarian hyperstimulation with the aromatase inhibitor letrozole in infertile ovulatory women. DESIGN: Prospective trial in infertile patients. SETTING: Tertiary care hospital. PATIENT(S): Eight ovulatory infertile patient candidates for ovarian superovulation. INTERVENTION(S): Subjects were monitored in one control cycle. In the next cycle, they received letrozole 5.0 mg daily on days 3 through 7 after menses. MAIN OUTCOME MEASURE(S): Number of ovulatory follicles; dominant follicle diameter; endometrial thickness; hormonal profile of FSH, LH, E(2), A, T, and P; endometrial histological dating; and pinopode formation assessed by scanning electron microscopy. RESULT(S): Cycles stimulated with letrozole resulted in more ovulatory follicles than did natural cycles (mean +/- SD 2.0 +/- 0.9 vs. 1.0 +/- 0.0), which attained a greater preovulatory diameter (mean +/- SD 23.8 +/- 2.7 vs. 19.3 +/- 2.1 mm), with similar endometrial thickness at midcycle compared with spontaneous cycles. Endocrine profile of medicated cycles was characterized on day 7 by increased levels of LH (5.9 +/- 0.8 vs. 3.5 +/- 0.4 IU/mL), reduced E(2) (98.4 +/- 11.4 vs. 161.5 +/- 14.7 pmol/L), and elevated androgens. Preovulatory and midsecretory E(2) were similar to spontaneous cycle, and P levels during midluteal phase were significantly elevated (44.2 +/- 4.6 vs. 27.7 +/- 4.6 pmol/L). Endometrial morphology during the implantation window in letrozole-stimulated cycles was characterized by in-phase histological dating and pinopode expression on scanning electron microscopy. CONCLUSION(S): Letrozole induces moderate ovarian hyperstimulation in ovulatory infertile patients with E(2) levels similar to spontaneous cycles and higher midluteal P, leading to both a normal endometrial histology and development of pinopodes, considered to be relevant markers of endometrial receptivity.

Published 17 January 2005 in Fertil Steril, 83(1): 110-5.
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