Anal Abscess

(Anal Rectal Abscess; Anorectal Abscess)

Definition

An anal abscess is a pus-filled pocket located in the spaces around the anus and rectum. An abscess can be found near the surface of the anal opening or deeper in the rectum.

Causes  ^

An anal abscess is caused by a bacterial infection. Infection may occur when there is a blockage in one or more of the anal glands that secrete mucous, or from an anal fistula.

The Anus
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Risk Factors  ^

Anal absesses are more common in men. Other factors that may increase your chance of an anal abscess include:

  • Certain conditions, such as Crohn's disease, ulcerative colitis, or sexually transmitted diseases
  • Medications that suppress the immune system
  • Pregnancy
  • Receptive anal intercourse

Symptoms  ^

Symptoms depend on where the abscess is located. An anal abscess may cause:

  • Painful bowel movements
  • Pain and tenderness radiating from the location of the abscess if it is near the surface
  • Lower abdominal pain if it is located deeper in the rectum
  • Redness and swelling—visible with a surface abscess, also occurs in a deep abscess, but cannot be seen
  • Pus drainage
  • Fever

Complications of an anal abscess may include:

  • Anal fistula—abnormal channel between the rectum and the surface of the anal skin leading to the outside
  • Systemic sepsis—serious, life-threatening infection that spreads throughout the body
  • Stool incontinence

Diagnosis  ^

Your doctor will ask about your symptoms and medical history. A physical exam will be done. An abscess near the surface of the skin may be visible. A deeper abcsess may require a digital rectal exam. The doctor will feel the inside of the anal canal for any abnormalities.

Imaging tests to look at anorectal structures may include:

Treatment  ^

Surgical drainage is necessary to treat an anal abscess. The type of procedure depends on its location and depth. It is possible that you may have a drain in the wound for up to 3 weeks to help the healing process.

Medications

Antibiotics are generally not necessary, but your doctor may recommend them under certain circumstances. Other medications may include:

  • Over-the-counter or prescription pain medication
  • Stool softeners, fiber, or bulk laxatives

Prevention  ^

To help reduce your chance of an anal abscess, be sure to manage any health conditions that increase your risk of infections.

RESOURCES:

American College of Gastroenterology
http://gi.org

American Society of Colon and Rectal Surgeons
http://www.fascrs.org

CANADIAN RESOURCES:

Canadian Association of Gastroenterology
https://www.cag-acg.org

Canadian Society of Colon and Rectal Surgeons
http://cscrs.ca

REFERENCES:

Abcarian H. Anorectal infection: Abscess-fistula. Clin Colon Rect Surg. 2011;24(1):14-21.

Anal abscess and fistula. American Society of Colon and Rectal Surgeons website. Available at: https://www.fascrs.org/patients/disease-condition/abscess-and-fistula-expanded-information. Updated October 2012. Accessed November 9, 2015.

Anal rectal abscess and fistula. Hemorrhoid website. Available at: http://www.hemorrhoid.net/abscess.php. Accessed November 9, 2015.

Anorectal abscess. John Hopkins Medicine website. Available at: http://www.hopkinsmedicine.org/healthlibrary/conditions/adult/digestive_disorders/anorectal_abscess_134,175. Accessed November 9, 2015.

Caliste X, Nazir S, Goode T. Sensitivity of computed tomography in detection of perirectal abscess. Am Surg. 2011;77(2):166-168.

Schaffzin DM, Wong WD. Surgeon-performed ultrasound: endorectal ultrasound. Surg Clin North Am. 2004;84(4):1127-1149.

Last reviewed November 2015 by Michael Woods, MD