Does non-cavity distorting intramural fibroid affect endometrium around the time of embryo implantation?

The effect of the intramural fibroids not distorting the cavity remains controversial on implantation and pregnancy. The aim of this study was to examine the impact of non-cavity distorting intramural fibroids on endometrium. Fifty-six women with non-cavity distorting intramural fibroid were recruited in this study. Paired endometrial specimens, one from beneath the fibroid (ipsilateral endometrium) and the other from the opposite side of uterine cavity, away from the fibroid (contralateral endometrium) were obtained 7-9 days after the luteinizing hormone surge in a natural cycle. Histological dating, Mucin1 and Glycodelin expression and uterine natural killer (uNK) cell density were compared between the paired samples. The median (IQR) H-score of Mucin1 staining in the ipsilateral luminal epithelium was 210% (142-230%), which was significantly (p < 0.05) higher than that of the contralateral luminal endometrium (157%, IQR 114-176%). There was no significant difference in Mucin1 expression in the glandular epithelium. There was no significant difference in Glycodelin expression in luminal and glandular epithelium, uNK cells density or histological dating results between the paired endometrial samples. In conclusion, it is uncertain whether the altered expression of Mucin1 in luminal epithelium alone may have impact on implantation when other markers are not changed.