Fistula-in-Ano Clinical Presentation

Updated: Jul 29, 2022
  • Author: Juan L Poggio, MD, MS, FACS, FASCRS; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Patients often provide a reliable history of previous pain, swelling, and spontaneous or planned surgical drainage of an anorectal abscess. Signs and symptoms of fistula-in-ano, in order of prevalence, include the following:

  • Perianal discharge
  • Pain
  • Swelling
  • Bleeding
  • Diarrhea
  • Skin excoriation
  • External opening

Important points in the patient’s history that may suggest a complex fistula include the following:

  • Inflammatory bowel disease
  • Diverticulitis
  • Previous radiation therapy for prostate or rectal cancer
  • Tuberculosis
  • Steroid therapy
  • HIV infection

A review of symptoms may reveal the following in patients with a fistula-in-ano:

  • Abdominal pain
  • Weight loss
  • Change in bowel habits

Physical Examination

Physical findings are the mainstay of diagnosis.

The examiner should observe the entire perineum, looking for an external opening that appears as an open sinus or elevation of granulation tissue. Spontaneous discharge of pus or blood via the external opening may be apparent or expressible on digital rectal examination.

Digital rectal examination (DRE) may reveal a fibrous tract or cord beneath the skin. It also helps to delineate any further acute inflammation that is not yet drained. Lateral or posterior induration suggests deep postanal or ischiorectal extension.

The examiner should determine the relationship between the anorectal ring and the position of the tract before the patient is relaxed by anesthesia. The sphincter tone and voluntary squeeze pressures should be assessed before any surgical intervention to determine whether preoperative manometry is indicated. Anoscopy is usually required to identify the internal opening. Proctoscopy is also indicated in the presence of rectal disease (eg, Crohn disease or other associated conditions). Most patients cannot tolerate even gentle probing of the fistula tract in the office, and this should be avoided.