II. Causes
-
Perirectal Abscess
- Fistula forms in 50% of cases
- Sequelae of rupture or surgery
- Anal Fissure
- Crohn's Disease
- Anorectal cancer
- Tuberculosis
- Local Radiation Therapy
- Lymphogranuloma venereum
- Obstetric Trauma (e.g. fourth degree peroneal Laceration)
III. Types
- Simple Rectal Fistula
- Complex Rectal Fistula criteria
- Anterior tract or
- Multiple tracts or
- Cross more than 50% of external anal sphincter or
- Recurrent
IV. Symptoms
- Chronic yellow, pustular (seropurulent) or mucus drainage from fistula
- Pain may be present at fistula tract
V. Signs
- Communicating tract between perianal skin and anus
- One or several external openings tracking toward anus
- Drainage may be spontaneous or with applying pressure with a finger from inside the anus
VI. Imaging
- MRI Pelvis (indicated in complicated Anal Fistulas)
VII. Associated Conditions
VIII. Management: Conservative Therapy
- Sitz baths
- High fiber diet
- Topical Analgesics
IX. Management: Surgery (Fistulotomy)
- Indications
- Non-healing fistula
- Complex Anal Fistulas
- Increased risk factors for complications (e.g. Horseshoe Ischiorectal Abscess)
- Adverse effects
- Fecal Incontinence risk with complex Anal Fistula surgical repair
- Protocol
- Fistulotomy is typically delayed until after Perirectal Abscess heals
- Surgical repair requires precise mapping of the fistula tract
- Fistula tracts are mapped with exam under Anesthesia, as well as MRI and Ultrasound
X. References
- Goroll (2000) Primary Care Medicine, Lippincott, p. 426
- Fargo (2012) Am Fam Physician 85(6): 624-30 [PubMed]