St Mark's protocol for standardised examination under anaesthesia for rectovaginal fistulae

Rectovaginal fistulae are uncommon but highly morbid, with presentations ranging from vaginal defaecation to subtle symptoms such as flatus, discharge, or recurrent infection. Imaging and contrast studies may be inconclusive for short, low-lying tracts, and ultrasound techniques can be limited by false-negative results. A structured examination under anaesthesia therefore remains central to definitive diagnosis and operative planning. The St Mark's protocol standardises this assessment using a reproducible five-stage sequence: (1) direct proctovaginal inspection with evaluation of the rectovaginal septum, perineal body, and anterior sphincter complex; (2) intraoperative endoanal ultrasonography where expertise permits; (3) probing to confirm patency of small or occult openings; (4) insufflation with a vaginal bubble test to demonstrate communication, particularly for higher fistulae; and (5) rectal methylene blue dye testing with isolated vaginal swabbing to confirm persistence. This paper describes the protocol and its role in consistent documentation, anatomical characterisation, and informed intraoperative decision-making.