Clomiphene's effect on endometrium in infertility

Secretory-phase endometrium from patients receiving clomiphene has an identifiable, distinctive character. We reviewed 710 endometrial biopsies from 566 infertility patients, including 108 from 79 patients receiving clomiphene. Endometrial glands in biopsies from clomiphene-treated patients were straight, narrow, and less tortuous than normal. Gland-to-stroma ratio was decreased. In the early secretory phase, glands had crisp subnuclear vacuoles and distinct glandular lumenal borders. Secretions were scant throughout the secretory phase, with few apical snouts. Lumenal secretions appeared inspissated and hyaline-like. Late secretory epithelium was generally low cuboidal and rarely showed hypersecretory change. Stromal predecidualization in the late phase showed progression, but in some cases decidual cells were smaller than usual. All of these features are consistent with a hypoestrogenic effect.