Your Health

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:
  • 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 your 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 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 http://www.cag-acg.org

Capital Health http://www.cdha.nshealth.ca

References

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

Anal abscess/fistula. American Society of Colon and Rectal Surgeons website. Available at: http://www.fascrs.org/patients/conditions/anal%5Fabscess%5Ffistula. Updated October 2012. Accessed November 14, 2013.

Anal rectal abscess and fistula. Hemorrhoid website. Available at: http://www.hemorrhoid.net/abscess.php. Accessed November 14, 2013.

Anorectal abscess. John Hopkins Medicine website. Available at: http://www.hopkinsmedicine.org/healthlibrary/conditions/adult/digestive%5Fdisorders/anorectal%5Fabscess%5F134,175. Accessed November 14, 2013.

Caliste X, Nazir S, et al. 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, vii.

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