Perianal transsphincteric fistulas - Crohn disease

Case contributed by Bruno Di Muzio
Diagnosis certain


Followup of known perianal disease. MRI to assess response to therapy.

Patient Data

Age: 20 years
Gender: Male

Trans-sphincteric fistula arising from 5 to 6 o'clock at the mid anus level tracks down to open in the left aspect of the perianal cleft. Seton sutures noted. The previously demonstrated complex perirectal tracts extension above the levator muscle is much less prominent compared to previous. No collections identified. No Seton suture within this extension. 

Trans-sphincteric fistula arising at 6 o'clock, just inferior to the above-mentioned fistula, is demonstrated with a track to the right ischial anal fossa and opening in the right natal cleft; it has an additional branch opening at the anterior aspect of the perineum. Seton sutures also present in these tracts. 

Van Assche score: Multiple (three) transsphincteric (two) infralevator (one) tracts with mild T2 hyperintensity (four).  Total score is 10/22.

Modified T-score: Multiple (three) transsphincteric (two) with a horseshoe configuration (two) and mild T2 hyperintensity (one).  Minimal inflammation in the surrounding tissue without collection.  Pronounced enhancement of the tract (two) and filled with granulation tissue (one). Total score is 11/25.

Case Discussion

Inflammatory changes related to complex multiple perianal trans-sphincteric fistulas. St James’s University Hospital classification: grade 3: trans-sphincteric.

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