The changes in resting anal pressure after performing full-thickness rectal advancement flaps

- Evaluation of the changes in resting pressure along the anal canal after performing a full-thickness flap.
- A manometric study.
- The importance of preserving the distal anal internal sphincter.

BackgroundAdvancement flap is an accepted approach for treating complex fistula-in-ano.The purpose was to evaluate the changes in resting pressure along the anal canal after performing a full-thickness flap.MethodsManometric review of patients who have undergone a full-thickness rectal advancement flap procedure for complex anal fistulas of cryptoglandular origin. Recurrence and continence were evaluated. Resting Anal Pressure was assessed along the anal canal by two measures: maximum resting pressure(MRP) and inferior resting pressure(IRP) at 0.5 cm from the anal verge.Results119 patients were evaluated. Overall recurrence rate was5.9%. Anal continence was maintained intact in 76.5%. Manometric study showed a significant decrease in postoperative MRP(90.6 ± 31.9 to 45.2 ± 20 mmHg; p < 0.001), while IRP values did not differ significantly(28.2 ± 18.3 to 23.2 ± 13.5 mmHg; p = 0.1).ConclusionsPerforming a full-thickness rectal flap causes a decrease of the MRP in the middle third of the anal canal, due to the inclusion of the internal sphincter in flap. It seems crucial to preserve the distal internal sphincter intact as it helps both to maintain the resting pressure in the lower third and avoid deformities of the anal margin.