An 81-year-old woman with early dementia was on a regular follow-up for change of Gellhorn pessary every 6 months for vault prolapse. She presented with frequency and urgency for 10 months duration 5 years into conservative management. Her symptoms did not improve on anticholinergics and lifestyle modifications. She underwent an opportunistic change of pessary under general anaesthesia coincidental to scalp wound debridement. On removal of the pessary, a gush of urine was noted followed by confirmation of a large vesico-vaginal fistula (VVF). In the initial period of follow-up, she was reviewed by the urogynaecology team and considered to be a poor surgical candidate for a major surgical procedure and was offered conservative measures with incontinence pads and possible indwelling catheter. Serious complications like fistulae can still occur despite well-managed pessary treatment. Earlier presentation with overactive bladder symptoms masked the VVF resulting in delayed diagnosis.