Rare case of abdominal scar endometriosis by direct communication between fallopian tube and abdominal wall

Introduction: Endometriosis involving a surgical scar occurs in 1%–2% of patients after cesarean section. There are three theories of pathogenesis: direct seeding of endometrium during surgery, distal migration by hematogenous or lymphatic routes, and scar tissue metaplasia. Retrograde menstruation, theorized to result in local pelvic endometriosis, has not been previously described to play a role in surgical scar endometriosis. Case report: A 36-year-old woman presented with a catamenial painful nodule in her cesarean section scar. She underwent laparoscopy with lysis of adhesions and excision of the abdominal wall nodule. The fimbriated end of the right fallopian tube was scarred to her abdominal wall at the site of the nodule, and chromopertubation proved direct communication between the painful nodule and the fallopian tube. Pathology confirmed surgical scar endometriosis. Conclusion: Retrograde menstruation remains a possible theory for pathogenesis of endometrial scar endometriosis, and laparoscopy should be considered at the time of resection when pelvic pain is present.