Combination anti-TNF and thiopurine therapy provides sustained benefit in patients with perianal CD fistula. Early clinical response is associated with subsequent clinical remission. Radiological healing is slower than clinical healing. Radiologically healed fistula tracts maintain healing on infliximab but can recur after cessation of therapy.

From the available literature, the summarized performance characteristics for MRI and endoanal ultrasound demonstrate comparable sensitivities at detecting perianal fistulas, although the specificity for MRI was higher than that for endoanal ultrasound. Both specificity values are considered to be diagnostically poor, however. The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice. Future trials with improved study design (including prospective data collection and consideration of verification bias) may help to further clarify the role of MRI in the assessment and treatment response monitoring of perianal fistulas (particularly in patients with Crohn's disease).

Background High perianal fistulas require sphincter‐preserving surgery because of the risk of faecal incontinence. The ligation of the intersphincteric fistula tract (LIFT) procedure preserves anal sphincter function and is an alternative to the endorectal advancement flap (AF). The aim of this study was to evaluate outcomes of these procedures in patients with cryptoglandular and Crohn's perianal fistulas. Methods A systematic literature search was performed using MEDLINE, Embase and the Cochrane Library. All RCTs, cohort studies and case series (more than 5 patients) describing one or both techniques were included. Main outcomes were overall success rate, recurrence and incontinence following either technique. A proportional meta‐analysis was performed using a random‐effects model. Results Some 30 studies comprising 1295 patients were included (AF, 797; LIFT, 498). For cryptoglandular fistula (1098 patients), there was no significant difference between AF and LIFT for weighted overall success (74·6 (95 per cent c.i. 65·6 to 83·7) versus 69·1 (53·9 to 84·3) per cent respectively) and recurrence (25·6 (4·7 to 46·4) versus 21·9 (14·8 to 29·0) per cent) rates. For Crohn's perianal fistula (64 patients), no significant differences were observed between AF and LIFT for overall success rate (61 (45 to 76) versus 53 per cent respectively), but data on recurrence were limited. Incontinence rates were significantly higher after AF compared with LIFT (7·8 (3·3 to 12·4) versus 1·6 (0·4 to 2·8) per cent). Conclusion Overall success and recurrence rates were not significantly different between the AF and LIFT procedure, but continence was better preserved after LIFT.

SUMMARY BackgroundCrohn's anal fistulas are common and cause considerable morbidity. Their management is often difficult; medical and surgical treatments rarely lead to true healing with frequent recurrence and complications. AimTo examine medical treatments previously and currently used, surgical techniques and the important role of optimal imaging. MethodsWe conducted a literature search in the Pub Med database using Crohn's, Anal Fistula, Surgery, Imaging and Medical Treatment as search terms. ResultsAntibiotics and immunosuppressants have a role, but slow initial response, side effects and relatively low remission rates of up to around a third with frequent recurrence limit their value. Long-term infliximab produces clinical remission in 36-58% of patients with combined medical and surgical management achieving optimal outcomes. Traditional and newer surgical procedures often have a high rate of recurrence with a significant risk of temporary or, in up to 10% of cases, permanent stomas, incontinence and unhealed or slowly healing wounds in 30%. ConclusionsManagement of Crohn's anal fistulas remains challenging. Established principles are to drain infection, use setons as required, aggressively manage active proctitis, give antibiotics, immunosuppressants and employ antiTNFa therapy, and they demand significant co-operation between gastroenterologists and surgeons.