A young woman with recurrent perianal sepsis

A 23 year old woman had been experiencing cramping abdominal pain, alternating diarrhoea and constipation, and episodic blood per rectum for four months. An earlier colonoscopy showed proctitis, which was thought to be indicative of underlying inflammatory bowel disease, and she was started on oral and topical mesalazine. In the following months she was admitted twice with acute perianal sepsis, which required examinations under anaesthesia and drainage of an intersphincteric abscess. She later presented after feeling generally unwell for four days with “flu-like” symptoms and perianal pain. On examination she had tenderness and fluctuance in the region of the right ischial tuberosity, with an external fistula opening visibly in the perineum. Her blood tests show mild neutrophilia (9.40×10⁹/L, reference range 2-7.5) and mildly raised C reactive protein (380.96 nmol/L (40 mg/L), 0-95.24 (0-10) only.