1. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Anatomic relationships in the perianal region.Modified with permission from: Fry RD, Kodner IJ. Anorectal disorders. Clin Symp. 1985; 37:2-32. Modified figure copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

2. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 The classification system of Parks and colleagues.A. A superficial fistula tracks below both the internal anal sphincter and external anal sphincter complexes. B. An intersphincteric fistula tracks between the internal anal sphincter and the external anal sphincter in the intersphincteric space. C. A transsphincteric fistula tracks from the intersphincteric space through the external anal sphincter. D. A suprasphincteric fistula leaves the intersphincteric space over the top of the puborectalis and penetrates the levator muscle before tracking down to the skin. E. An extrasphincteric fistula tracks outside of the external anal sphincter and penetrates the levator muscle into the rectum. Modified with permission from reference 19. Modified figure copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

3. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Surgical approach to perianal abscess drainage.A. Simple incision and drainage procedure for an abscess. B. Incision and drainage followed by placement of a mushroom drainage catheter for an abscess. Copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

4. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Placement of a noncutting seton.A noncutting seton is a suture or drain that is threaded into the cutaneous orifice of a perianal fistula, through the fistula tract, across the mucosal orifice of the fistula into the rectum, and through the rectum across the anus, where the two ends of the suture or drain are loosely tied. Copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

5. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Fistulotomy.In the absence of active proctocolitis, simple low trans-sphincteric, intersphincteric, and superficial fistulas can be treated with a fistulotomy. Copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

6. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Endorectal advancement flap.A. The fistula tract is probed to identify the internal opening of the fistula. B. The internal opening of the fistula tract is incised. C. A flap of tissue (including mucosa, submucosa, and circular muscle) around the site of the resected internal opening of the fistula is incised. D. The flap is pulled down to cover the site of the resected internal opening of the fistula. Copyright 2000, Mayo Clinic. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

7. Date of download: 6/9/2016 From: Diagnosis and Treatment of Perianal Fistulas in Crohn Disease Ann Intern Med. 2001;135(10):906-918. doi:10.7326/0003-4819-135-10-200111200-00011 Treatment algorithm for perianal Crohn disease.If the fistula is simple, endorectal advancement flap (asterisk) or fistulotomy (†) can be considered. Use of infliximab should be favored if the fistula is complex, recurrent, or associated with active rectal inflammation (‡). 6-MP = 6-mercaptopurine; AZA = azathioprine; EUS = endoscopic ultrasonography; MRI = magnetic resonance imaging. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians