Is tubal endometriosis an asymmetric disease? A 17-year retrospective study

To investigate whether there are left–right asymmetries in tubal endometriosis and the factors affecting this predisposition. Women who underwent salpingectomy for gynecological diseases and were diagnosed with tubal endometriosis between January 2002 and July 2019 were included in the study. The frequencies of left and right tubal endometriosis were compared with the expected 50% using a binominal test. The demographic characteristics and presence of ovarian endometrioid cysts, adenomyosis, and hydrosalpinx were also analyzed. During the study period of more than 17 years, 305 women were diagnosed with tubal endometriosis. The distribution of tubal endometriosis in the left or right fallopian tubes was analyzed. Tubal endometriosis was found in the left fallopian tube in 168 (55.08%) women, in the right fallopian tube in 93 (30.49%), and bilaterally in 44 (14.43%). Left unilateral tubal endometriosis was found most frequently (64.37%, 168/261), and its incidence was significantly higher than 50% (P < 0.001, binominal test). Furthermore, the frequency of left ovarian endometrioid cysts (58.82%) was higher than that of right ovarian endometrioid cysts (41.18%) (P < 0.001, binominal test). Our study confirms that tubal endometriosis is a left-side asymmetric disease, and this predisposition is highly consistent with ovarian endometrioid cysts, which supports the transplantation theory of the origin of endometriosis.