The post-operative decline in serum anti-Mullerian hormone correlates with the bilaterality and severity of endometriosis

BACKGROUND To assess the impact of ovarian cystectomy for endometriomas on the ovarian reserve, we evaluated the pre- and post-operative levels of serum anti-Müllerian hormone (AMH). We also analyzed the correlations between factors related to endometriosis and surgery for endometriomas and the serum AMH levels to investigate which factors affect ovarian reserve. METHODS Thirty-eight patients who were undergoing ovarian cystectomy for unilateral endometrioma (n = 20) and bilateral endometriomas (n = 18) participated. Preoperative and post-operative serum samples were collected and assayed for AMH levels, and changes between the two samples were analyzed in association with parameters of endometriosis and surgery for endometriomas. RESULTS The mean AMH level was 3.9 ng/ml prior to surgery, and was reduced to 2.1 ng/ml at 1 month post-surgery. The rate of decline of the serum AMH level was significantly higher in the bilateral group than the unilateral group (62.8 ± 29.6 versus 24.7 ± 32.5%, P < 0.001). The rate of decline in the serum AMH levels showed a significant correlation to the revised American Society for Reproductive Medicine (rASRM) score (P = 0.003), but not age, cyst diameter, blood loss during the operation or the number of follicles removed in the specimens. CONCLUSIONS Our results suggest that the decrease in ovarian reserve should be taken into account in patients indicated for cystectomy for bilateral endometriomas or unilateral endometrioma with high rASRM scores.