Spontaneous Fistula and Abdominal Wall Endometriosis Due to Occult Existence of Unicornuate Right Uterus with Rudimentary Non-Communicating Functioning Left Horn

Accurate diagnosis of Mullerian duct anomalies (MDA) remains a clinical challenge even by direct surgical inspection. Although obstetrical complications are more frequent in women with MDA, some subtypes allow normal reproduction, further delaying the diagnosis. Unicornuate uterus with a rudimentary non-communicating functioning horn is a rare form of MDA, susceptible to many gynecologic and obstetric complications such as miscarriages, premature birth, hematosalpinx, endometriosis, and chronic pelvic pain. We present an entire case pictorial assay including preoperative imaging as well as the surgical correction of the uterine anomaly and the associated complication of an occult unicornuate right uterus with rudimentary non-communicating functioning left horn (Class U4aC0V0/ European Society of Human Reproduction and Embryology/European Society of Gastrointestinal Endoscopy Classification) and its natural evolution following a previous incomplete surgical treatment. The patient had an emergency left adnexectomy for hematosalpinx and ovarian endometrioma at her local county hospital. After five years, the patient presented with severe dysmenorrhea and abdominal endometriosis due to blocked retrograde menstruation from a rudimentary, non-communicating functioning horn. Surgical treatment with the resection of the rudimentary uterine horn, together with the abdominal wall endometriosis lesions, was carried out with good outcomes.