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

Abstract Background: To evaluate the influence of the location of endometrioma (right vs. left ovary) on endometriosis severity, we compared the revised American Society for Reproductive Medicine (ASRM) scores determined by laparoscopic surgery. Methods: The medical records of 151 patients, including 58 right-sided and 93 left-sided cases, who underwent initial laparoscopic surgery for unilateral ovarian endometrioma were reviewed retrospectively. We extracted the ASRM scores determined during surgery and some representative factors relating to endometirosis that are separate from tumour characteristics, such as the coexistence of uterine fibroid, adenomyoma, or other ovarian tumours, a history of assisted reproductive technology (ART), and tumour marker values. Multivariate 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. Opposite endometrial lesion (OEL), Douglas pouch endometrial lesion (DEL), same endometrial lesion (SEL) and peritoneal endometrial lesion (PEL) were defined. Results: The ASRM scores of patients with right-sided endometrioma were significantly higher than those of patients with left-sided endometrioma (41.5 ± 22.0 points vs. 33.5 ± 16.3 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-sided tube, left-sided ovary and Douglas pouch. Multivariate analysis revealed that the coexistence of uterine fibroid or adenomyoma also had significant positive impacts 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.