Ultrasound Assessment After Surgery for Chronic Anal Fissure

Chronic anal fissure is a painful tear in the lining of the anal canal that may not heal with medication or other non-surgical treatments. Lateral internal sphincterotomy (LIS) is a commonly used surgical treatment. However, the amount of internal anal sphincter muscle divided during surgery may affect both fissure healing and the risk of impaired bowel control. The purpose of this prospective observational study is to assess whether the extent of internal anal sphincter division, measured using three-dimensional endoanal ultrasound, is associated with fissure healing and changes in anal continence during the first year after surgery. The study will include 66 adults with chronic anal fissure undergoing open or closed lateral internal sphincterotomy as part of their usual clinical care. The surgical technique will be selected by the treating clinical team and will not be assigned by the researchers. Participants will be assessed before surgery and at 3, 6, and 12 months after surgery. At the 3-month visit, they will undergo two-dimensional and three-dimensional endoanal ultrasound. Two independent observers will separately review the stored ultrasound images. Follow-up assessments will evaluate fissure healing or recurrence, bowel control, faecal soiling, pain, bleeding, postoperative complications, and quality of life. The findings may help identify the extent of sphincter division that provides effective fissure healing while limiting the risk of postoperative anal incontinence.