Influence of laterality on endometriosis severity in patients with unilateral endometrioma: a retrospective study.

Abstract Background: We compared the revised American Society for Reproductive Medicine (ASRM) scores determined during laparoscopic surgery to evaluate the effect of the location of the endometrioma (right vs. left ovary) on the severity of endometriosis. Methods: The medical records of 151 patients, including 58 right-sided and 93 left-sided cases, who underwent an initial laparoscopic surgery for unilateral ovarian endometrioma were reviewed retrospectively. We extracted the ASRM scores determined during surgery and some representative factors related to endometriosis that are separate from the tumour characteristics, such as the coexistence of uterine fibroids, adenomyoma, or other ovarian tumours, a history of use of assisted reproductive technology (ART), and tumour marker values. A statistical analysis was performed to assess the impact of each factor. We classified the ASRM scores into 4 categories to compare the tendency towards endometrial lesion spread with a focus on the “sidedness” of the endometrioma. We defined contralateral endometrial lesion (CEL), Douglas pouch endometrial lesion (DEL), same endometrial lesion (SEL) and peritoneal endometrial lesion (PEL). Results: The ASRM scores of patients with a right-sided endometrioma were significantly higher than patients with a left-sided endometrioma (41.5 ± 22.1 points vs. 32.9 ± 15.8 points, p<0.05). The higher ASRM scores of the patients with right-sided endometrioma may be caused by the frequent detection of endometrial lesions in the left tube, left ovary and Douglas pouch. According to the statistical analysis, the coexistence of uterine fibroids also exerted significant positive effects on increasing the ASRM score. Conclusions: Higher ASRM scores are possible in patients with right-sided endometrioma. The laterality of endometriosis severity should be considered.