Treatment of Crohn’s anal fistulas guided by magnetic resonance imaging

Introduction
Clinical evaluation of the Crohn’s anal fistulas (CF) closure is inadequate to some extent due to earlier closure of cutaneous openings compared to fistulous tracts. There is a need for a more accurate method of assessment.

Aim
To compare clinical signs of CF with radiological findings, before and after treatment, to follow complete closure.

Material and methods
It was a retrospective study of 23 patients suffering from CF admitted to a single specialist centre, who were treated with a combination of surgical and biological therapy. Fistula healing was evaluated with fistula drainage assessment classification (FDA), perianal disease activity index (PDAI), and van Assche magnetic resonance imaging score (MRI) before and 3 months after surgery and induction of the biological treatment.

Results
Clinical response occurred in 13 (57%) patients 3 months after induction treatment. Complete clinical response was achieved in 8 (35%) patients, whereas partial response occurred in 5 (22%) patients. Persistence of a fistula tract was visualised on MRI in 4 (50%) patients with clinical closure.

Conclusions
The healing process of CF should be monitored by MRI due to the discrepancy between premature closure of external openings and fistulous tracts. Prolonged biological therapy until complete healing of anal fistulas confirmed on MRI might improve the results of treatment.