Round Ligament Endometriosis Mimicking Chronic Postoperative Inguinal Pain Following Robotic Inguinal Hernia Repair: A Case Report and Brief Literature Review.

Chronic postoperative inguinal pain (CPIP) affects an estimated 4%-21% of patients following inguinal hernia repair, with rates varying by technique, follow-up duration, and pain definition, and requires a systematic, multidisciplinary evaluation. Inguinal endometriosis is a rare entity, representing approximately 0.07% of all endometriosis cases, and is an uncommonly recognized cause of inguinal pain that may mimic CPIP. We present the case of a 37-year-old woman who developed new left-sided groin pain following an elective bilateral robotic transabdominal preperitoneal inguinal hernia repair. Initial workup, including physical examination and magnetic resonance imaging (MRI), was unremarkable, and conservative management with activity modification, analgesics, and a targeted nerve block provided no sustained relief. At 16 months postoperatively, the patient reported a palpable tender nodule near the left pubic symphysis with symptoms that had become clearly cyclical in nature. A repeat MRI timed to coincide with her menstrual cycle revealed soft tissue inflammation along the left round ligament near the pubic tubercle. Surgical excision of the round ligament with concurrent ilioinguinal neurectomy was performed, and histopathological analysis confirmed endometriosis. The patient experienced complete resolution of her cyclical pain postoperatively. A brief literature review of 21 published studies on inguinal and round ligament endometriosis was performed, which demonstrated that right-sided disease predominates, cyclical symptoms are common but not universal, and misdiagnosis is frequent. This case highlights the importance of considering inguinal endometriosis in the differential diagnosis of CPIP in women of reproductive age, particularly when symptoms are cyclical or localized outside the expected operative field. Additionally, this case underscores the potential diagnostic value of timing imaging studies to coincide with symptomatic windows to improve sensitivity for catamenial pathology.