Arguments for a left lateral predisposition of endometrioma.

Objective: To analyze a hypothesis regarding the pathogenesis of endometriosis.

Design: Retrospective study.

Setting: Two academic endometriosis referral centers.

Patient(s): We evaluated operative and pathologic reports of 251 women who underwent laparoscopic or laparotomy treatment of endometrioma from August 1996 to February of 2002 at Yale University School of Medicine and at the University of Crete Department of Obstetrics and Gynecology.

Intervention(s): Laparascopic examination.

Main Outcome Measure(s): Statistical methods included chi(2) and Mann-Whitney U tests measuring incidence of right- vs. left-sided endometria.

Result(s): One hundred seventy patients from Yale University and 81 Greek patients participated in this study. Endometrioma was significantly more frequent in the left ovary (139 of 206 [67.4%]) than in the right ovary (67 of 206 [32.6%]; odds ratio [OR] = 4.3; 95% confidence interval [CI) 2.9-6.5; chi(2) = 48.9) and significantly different from the expected proportion of 50% (chi(2) = 25.2). When bilateral endometriomas were included, 62.1% (184 of 296) were left-sided and 37.15 (112 of 296) were right-sided (OR = 17.5; 95% CI 1.9-3.8; chi(2) = 34.1). Dilated ovarian veins in were found in 22 (68.7%) of 32 Greek cases with endometrioma. All 20 women with left endometrioma had left ovarian vein dilated.

Conclusion(s): We suggest a new mechanical theory of implication, the female varicocele theory, which could play an important role in the development of ovarian endometriosis or endometriomas.