Use of clomiphene citrate protocol for controlled ovarian stimulation impairs endometrial maturity

Abstract

Introduction: Despite recent advances in assisted reproduction techniques and recent knowledge regarding embryo and endometrium quality, implantation and birth rates remain low. The objective of this study was to investigate whether clomiphene citrate alters endometrial maturation in infertile patients.

Methods: In a prospective self-matched cohort study, we assessed the ovulation of women in spontaneous and stimulated cycles (with clomiphene citrate). We determined the ovulation day by ultrasound scanning. In both cycles, we took four blood samples (BS1 - at early proliferative phase, BS2 - at mid proliferative phase, BS3 - after ovulation and BS4 - at mid luteal phase) to determine the serum concentrations of FSH, LH, estradiol and progesterone. We retrieved an endometrial biopsy five days after ovulation, followed by blinded analysis and classification according to Noyes criteria, in both cycles.

Results: Twenty-two participants completed the study. There were significant differences in FSH BS3 (p=0.001), in LH BS3 and BS4 (p<0.001 and p=0.049, respectively), in estradiol BS2, BS3 and BS4 (p<0.001, p=0.024 and p<0.001, respectively) and in progesterone BS3 and BS4 (p=0.028 and p<0.001, respectively). Considering Noyes criteria, there was a one-day delay when comparing the stimulated cycle with the spontaneous cycle (p=0.004), and a two-day delay when comparing the stimulated cycle with the biopsy day.

Conclusion: This study indicates that ovarian stimulation with clomiphene citrate delays the endometrial maturity, and could possibly impair the implantation process due to asynchrony.

Keywords: IVF; Noyes criteria; assisted reproduction techniques; endometrial maturity; endometrial receptivity.

Conflict of interest statement

CONFLICT OF INTEREST

All authors have completed the ICMJE uniform disclosure and declare that there was no support from any organization for the submitted paper, no financial relationships with any organizations that might have an interest in the submitted study in the previous 3 years and no other relationships or activities that could appear to have influenced the submitted study.

Figures

Figure 1

Schematic representation of the assessments in spontaneous and stimulated cycles. Following a spontaneous cycle, all 22 participants underwent a stimulated cycle using 100 mg/day of clomiphene citrate between days 3 and 7 of the cycle. When the leading follicle had a diameter of 17 mm (represented by **), they received 10.000 UI of human chorionic gonadotrophin (hCG) for final oocyte maturation. Endometrial biopsy (EB) was performed 5 days after ovulation confirmation (represented by *) by ultrasonography. In both cycles blood samples (BS) were taken at the early proliferative phase (days 1 -3), in the midproliferative phase (days 8-10), when confirmed ovulation, and five days after ovulation.

Figure 2

Participants’ causes of infertility.

Figure 3

Endometrial cycle dating based on Noyes et al. (1950) criteria (200x): (A) Day 17: “piano key” appearance of glandular epithelium with vacuoles at nuclei level; (B) Day 18: luminal vacuoles with smaller size and the nuclei approaching the base of the glandular cell; (C) Day 19: presence of intraluminal secretion with few vacuoles on cellular cytoplasm, absence of mitosis and pseudo stratification; (D) Day 20: the peak of intraluminal secretion with stromal edema onset, presence of rare vacuoles and round nuclei located at the base of the glandular cell.; (E) Day 23: presence of prominent spiral arterioles with thickened walls, coiling and endothelial proliferation; (F) stromal-glandular dissociation - gland on day 17 with decidualized stroma.

Figure 4

Median comparison of Noyes criteria results.