PANCE Blueprint GI and Nutrition (9%)

Rectal Abscess and Fistula (Lecture)

Patient will present as → a 47-year-old man with severe rectal pain when he defecates. He has a fever of 102.2 F (39 C). On exam there is perianal swelling, redness and tenderness. A palpable mass is felt at the anal verge as seen here.

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What disease should be considered with fistula in ano?
Crohn’s disease
What is a sitz bath?
Sitting in a warm bath (usually done after bowel movement and TID)

An anorectal abscess is a result of infection, whereas a fistula is a chronic complication of an abscess.

  • Abscesses produce painful swelling at the anus as well as painful defecation. Examination reveals localized tenderness, erythema, swelling, and fluctuance; fever is uncommon.
  • Deeper abscesses may produce buttock or coccyx pain and rectal fullness; fever is more likely.

On examination, an abscess will be red and tender and may be discharging purulent or hemorrhagic fluid. There will likely be some degree of surrounding cellulitis.

Anorectal fistula is an open tract between two epithelium-lined areas and is associated with deeper anorectal abscesses

  • Communication between the rectum and perianal skin
  • Generally located within 3 cm of the anal margin
  • Fistulae will produce anal discharge and pain when the tract becomes occluded.

Anal Abscess

  • Clinical - perirectal tender swollen mass
  • CT scan of pelvis only if recurrent

Fistula in Ano (Perianal Fistula)

  • Anoscopy

Treatment of abscess requires surgical drainage, followed by warm-water cleansing, analgesics, stool softeners and a high-fiber diet are prescribed for all patients

  • Prompt incision and adequate drainage are required and should not wait until the abscess points. Many abscesses can be drained as an in-office procedure; deeper abscesses may require drainage in the operating room
  • Antibiotics are needed for high-risk patients

Fistula must be treated surgically

Fistula Causes


A fistula is a connection or passageway formed abnormally between two epithelium-lined vessels or organs. Causes of enterocutaneous fistulas can be summarized by the mnemonic “FRIEND.” The “FRIENDs” of a fistula include Foreign body, Radiation, Infection, Epithelialization, Neoplasm, and Distal obstruction.

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Question 1
A patient presents complaining of blood during bowel movements. She is found to have multiple perianal fistulas on rectal examination. There is also a history of episodic diarrhea, mid and lower abdominal pain/cramping, fatigue, and weight loss. Which of the following is the most likely diagnosis?
Discomfort is a common symptom, especially during bowel movements or when sitting. Other symptoms include itching and bleeding. Perianal fistulas, episodic diarrhea, abdominal pain, cramping, fatigue, and weight loss are not associated with hemorrhoids.
Crohn's disease
Irritable bowel syndrome
Symptoms include abdominal pain, bloating, diarrhea, and constipation. Perianal fistulas are not associated with IBS.
Usually, no symptoms occur, unless the diverticula become inflamed or infected (diverticulitis) which can result in fever and abdominal pain.
Question 1 Explanation: 
Patients with Chron's disease often present with abdominal pain, weight loss, diarrhea (non-bloody), and oral mucosal aphthous ulcers. Patients with longer-standing disease may have severe anemia, polyarthralgia, and fatigue. The most common site is the terminal ileum. Obstruction, abscess, fistula, and sinus tracts are common
There is 1 question to complete.
Shaded items are complete.

References: Merck Manual · UpToDate

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