Closing the internal opening with a rectal advancement flap increases the efficacy of mesenchymal stem cell injection for complex Crohn's disease anal fistulas.

Abstract

The efficacy of injections of mesenchymal stem cells (MSC) for anal fistula treatment may be impaired by the persistence of stools passing into the fistula, causing bacterial contamination and a local inflammatory reaction. We aimed to compare remission rates between patients treated by MSC injection with simple sutures and those treated with a rectal advancement flap. This single-center prospective study compared the first patients who underwent internal opening closure with sutures with the subsequent patients treated with a flap. Complete clinical remission was defined as complete closure of the external opening(s) without pain or discharge, and complete radiological remission was defined as a Magnifi-CD score of 0. We compared the first 42 patients who had sutures with the 20 subsequent patients who had an advancement flap. The median follow-up was 15.5 [8.8-24.9]months. The cumulative incidence of complete clinical response at M12 was 53.8% [38.1-69.6%] in the suture group versus 93.3% [77.4-100.0] in the flap group (p < 0.001). The Magnifi-CD score was 0 for 41.7% [25.5-59.2%]) of patients treated with sutures versus 72.7% [39.0-63.9%]) of patients treated with a flap (p=0.093). Anal incontinence score did not differ between the two groups. Practicing an advancement flap was the only significant factor associated with complete clinical remission over time (adjusted HR [95% CI] of 2.6 [1.4-4.9], p = 0.003). Complete clinical remission rates following MSC injection are significantly higher after closure of the internal opening with a rectal flap than after closure with sutures, without consequences on anal continence.