A 36-year-old lady, with a past medical history of hydrocephalus requiring a ventriculoperitoneal (VP) shunt, was admitted with symptoms and signs of large bowel obstruction. Her condition worsened and she underwent laparotomy, where she had faecal peritonitis secondary to a perforated sigmoid colon. The shunt was contaminated with faeces leading to postoperative shunt infection and meningitis. Histology of the resected sigmoid colon revealed endometriosis at the site of perforation. Endometriosis is a rare cause of large bowel obstruction and literature review has found only two other cases of perforation because of endometriosis not associated with pregnancy. No case has been reported involving the concurrent surgical management of a contaminated VP shunt. We discuss the rarity of large bowel perforation and obstruction because of endometriosis, and the complications and management of VP shunts.