Endometrioma-related reduction in ovarian reserve (ERROR): a prospective longitudinal study.

<bold>Objective: </bold>To evaluate whether endometrioma is associated with a progressive decline in ovarian reserve, and to compare the rate of decline with natural decline in ovarian reserve.<bold>Design: </bold>Prospective, observational study.<bold>Setting: </bold>Tertiary university hospital, endometriosis clinic.<bold>Patient(s): </bold>Forty women with endometrioma and 40 age-matched healthy controls.<bold>Intervention(s): </bold>Women with endometriomas who did not need hormonal/surgical treatment at the time of recruitment and were expectantly managed. Controls were age-matched, healthy women. All participants underwent serum antimüllerian hormone (AMH) testing twice, 6 months apart. Sexually active patients with endometrioma also underwent antral follicle count.<bold>Main Outcome Measure(s): </bold>Change in serum AMH levels.<bold>Result(s): </bold>Median (25th-75th percentile) serum AMH level at recruitment was 2.83 (0.70-4.96) ng/mL in the endometrioma group and 4.42 (2.26-5.57) ng/mL in the control group. The median percent decline in serum AMH level was 26.4% (11.36%-55.41%) in the endometrioma group and 7.4% (-11.98%, 29.33%) in the control groups. Twenty-two women with endometrioma who had antral follicle count (AFC) had median AFC of 10 (8-12) at recruitment and 8 (6.3-10) at 6 months.<bold>Conclusion(s): </bold>Women with endometrioma experience a progressive decline in serum AMH levels, which is faster than that in healthy women.<bold>Clinical Trial Registration Number: </bold>NCT02438735. [ABSTRACT FROM AUTHOR]