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Anorectal Abscess

- Bacterial invasion of the anal glands found in the intersphincteric space, which may begin with an abrasion or tear in lining of anal canal, rectum, or perianal skin - The internal anal sphincter serves as a barrier to infection between gut lumen and perianal tissues. - Four types: Perianal (perirectal) is the most common (60%). Ischiorectal is the next most common followed by intersphincteric and supralevator (1)[C]. - Organisms (usually mixed aerobic; anaerobic) (2)[C] - Escherichia coli - Streptococci - Staphylococci (especially methicillin-resistant) - Bacteroides fragilis - Pseudomonas aeruginosa

- Inciting trauma - Injections for internal hemorrhoids - Enema tip abrasions - Puncture wounds from eggshells or fish bones - Foreign objects - Prolapsed hemorrhoid

- Ischiorectal abscess - Incise and drain abscess. - General anesthetic usually required - Pack wound with iodoform gauze or similar packing (removed gradually over several days). - Fistulectomy may be done at the same time in selected cases.

- Treatment of anorectal fistula at time of abscess drainage may be performed: - Recurrent abscess risk lower when fistula treated at same procedure - Incontinence risk higher when fistula treated as delayed procedure - Recommended in cases of SC, intersphincteric, or low transsphincteric fistula - Fistula-in-ano in children may spontaneously resolve; avoid immediate surgical intervention.

- Postoperative care - Sitz baths every 2 to 4 hours - Simplest method is to sit in bathtub with warm water, with or without additives such as Epsom salts

- Heating pad or warm compress as needed for pain - Encourage mobility. - Prevent constipation.

para>A high pelvirectal abscess may cause minimal symptoms, such as lower abdominal pain and fever.

Pediatric Considerations

Common in 1st year of life

EPIDEMIOLOGY

  • Predominant age: all ages (most common in 3rd and 4th decades and during infancy)
  • Predominant sex: male > female (2 to 3:1)

Incidence

Common

ETIOLOGY AND PATHOPHYSIOLOGY

  • Bacterial invasion of the anal glands found in the intersphincteric space, which may begin with an abrasion or tear in lining of anal canal, rectum, or perianal skin
  • The internal anal sphincter serves as a barrier to infection between gut lumen and perianal tissues.
  • Four types: Perianal (perirectal) is the most common (60%). Ischiorectal is the next most common followed by intersphincteric and supralevator (1)[C].
  • Organisms (usually mixed aerobic; anaerobic) (2)[C]Escherichia coliStreptococciStaphylococci (especially methicillin-resistant)Bacteroides fragilisPseudomonas aeruginosa

RISK FACTORS

  • Inciting traumaInjections for internal hemorrhoidsEnema tip abrasionsPuncture wounds from eggshells or fish bonesForeign objectsProlapsed hemorrhoid
  • Inflammatory bowel disease
  • Chronic granulomatous disease (especially Crohn disease)
  • Immunodeficiency disorders
  • Hematologic malignancies (5-8% of these patients will have abscess at some time.)
  • Diabetes mellitus
  • Chronic medical immunosuppression
  • Morbid obesity

GENERAL PREVENTION

  • Avoid constipation.
  • Avoid rectal thermometers, enemas, or suppositories whenever possible in immunocompromised patients.

COMMONLY ASSOCIATED CONDITIONS

  • Crohn disease
  • Other inflammatory disease (e.g., appendicitis, salpingitis, diverticulitis)
  • Consider perianal hidradenitis suppurativa or HIV infection in patients with recurring perianal or ischiorectal abscesses.
  • Consider anal fistula in patients with recurrent perianal abscesses in same location.

DIAGNOSIS

HISTORY

  • Perirectal pain, particularly on defecation or with sitting
  • Constipation
  • Fever, chills
  • Spontaneous foul-smelling drainage

PHYSICAL EXAM

  • Fever (20%)
  • Perirectal swelling (superficial abscesses)
  • Perirectal redness, tenderness
  • Digital rectal exam (DRE) with swollen tender mass
  • DRE is mandatory. If not possible due to pain, examination under anesthesia (EUA) must be arranged.

DIFFERENTIAL DIAGNOSIS

  • Hemorrhoidal disease
  • Proctitis
  • Rectal prolapse
  • Necrotizing soft tissue infection
  • Carcinoma
  • Crohn disease
  • Primary syphilis
  • Tuberculous ulceration
  • Anal fissure

DIAGNOSTIC TESTS & INTERPRETATION

  • History and physical are usually sufficient in cases of superficial anorectal abscess. If deep abscess is suspected (or if patients have complex anorectal disease), further imaging/testing is helpful.
  • CBC: leukocytosis
  • CT scan of pelvis (particularly deep abscess suspected)
  • Endoanal ultrasound
  • MRI is most sensitive (90%) for imaging perirectal abscesses.

Initial Tests (lab, imaging)

Follow-Up Tests & Special Considerations

  • Culture and sensitivity help guide antibiotic treatment (especially in high or extensive abscess).
  • 40% incidence of fistula if intestinal organisms cultured from the wound

Diagnostic Procedures/Other

Only indicated if diagnosis in doubt

  • Endoscopy: particularly for complex cases
  • Fistulography

Test Interpretation

  • Inflammation of anal mucosa
  • Possible fistula tract

TREATMENT

GENERAL MEASURES

  • Incision and drainage with packing is the primary treatment of choice for perianal abscesses (3)[B].
  • Simple abscesses can be treated in office or ED under local anesthesia. More complex cases require admission.
  • Inpatient surgery with IV antibiotics for supralevator abscess or clinical toxicity

MEDICATION

  • Antibiotics have a limited role in the treatment of uncomplicated anorectal abscesses.
  • Antibiotics may have a role in immunocompromised patients, diabetics, morbidly obese, and patients with extensive cellulitis or concomitant systemic illness.

First Line

  • Antibiotics (gram-negative and anaerobic coverage; based on culture results). Consider coverage for methicillin-resistant Staphylococcus aureus as well.
  • Stool-softening laxatives:Docusate sodium (50 to 300 mg/day)Polyethylene glycol 3350 (17 g/day)

SURGERY/OTHER PROCEDURES

  • Perianal abscessIncision and drainagePain control is important. Local anesthetic with small abscessesPack wound with iodoform gauze (24 to 48 hours).
  • Ischiorectal abscessIncise and drain abscess.General anesthetic usually requiredPack wound with iodoform gauze or similar packing (removed gradually over several days).Fistulectomy may be done at the same time in selected cases.
  • Supralevator abscessIncise and drain abscess into lower rectum or anal canal.General anesthesia required
  • Treatment of anorectal fistula at time of abscess drainage may be performed:Recurrent abscess risk lower when fistula treated at same procedureIncontinence risk higher when fistula treated as delayed procedureRecommended in cases of SC, intersphincteric, or low transsphincteric fistulaFistula-in-ano in children may spontaneously resolve; avoid immediate surgical intervention.

INPATIENT CONSIDERATIONS

Admission Criteria/Initial Stabilization

  • Fever
  • Systemic toxicity
  • Complex or extensive abscesses

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

  • Postoperative careSitz baths every 2 to 4 hoursSimplest method is to sit in bathtub with warm water, with or without additives such as Epsom saltsHeating pad or warm compress as needed for painEncourage mobility.Prevent constipation.
  • Analgesics for pain
  • Stool-bulking agents (psyllium) and stool softeners to prevent constipation
  • Resume work and normal activity as soon as possible.

Patient Monitoring

Routine postoperative care with attention to wound healing, which should progress from the inside out

DIET

Increase fiber and fluid intake.

PATIENT EDUCATION

  • Sitz bath instructions
  • Dietary instructions to increase fiber
  • Dressing change education
  • Perianal hygiene
  • Watch for possible development of fistula-in-ano.
  • Stress stool regularity; avoid constipation.

PROGNOSIS

  • Healing depends on extent of disease and concurrent illnesses; complete healing by 6 months in uncomplicated cases
  • Healing in infants may be complete in 1 to 3 weeks.
  • Drainage alone results in cure rate of 50% or more.

COMPLICATIONS

  • Fistula formation (in 30-60% of patients)
  • Fecal incontinence due to sphincteric rupture
  • Recurrence common in adults, less common in children <2 years of age
  • Necrotizing infection with rapid progression, sepsis, and death

REFERENCES

11 Rizzo JA, Naig AL, Johnson EK. Anorectal abscess and fistula-in-ano: evidence-based management. Surg Clin North Am. 2010;90(1):45-68.22 Brook I, Frazier EH. The aerobic and anaerobic bacteriology of perirectal abscesses. J Clin Microbiol. 1997;35(11):2974-2976.33 Malik AI, Nelson RL, Tou S. Incision and drainage of perianal abscess with or without treatment of anal fistula. Cochrane Database Syst Rev. 2007;(7):CD006827.

ADDITIONAL READING

  • Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rectal Surg. 2011;24(1):14-21.
  • AfÅŸarlar CE, Karaman A, Tanir G, et al. Perianal abscess and fistula-in-ano in children: clinical characteristic, management and outcome. Pediatr Surg Int. 2011;27(10):1063-1068.
  • Caliste X, Nazir S, Goode T, et al. Sensitivity of computed tomography in detection of perirectal abscess. Am Surg. 2011;77(2):166-168.
  • Niyogi A, Agarwal T, Broadhurst J, et al. Management of perianal abscess and fistula-in-ano in children. Eur J Pediatr Surg. 2010;20(1):35-39.
  • Oliver I, Lacueva FJ, P ©rez Vicente F, et al. Randomized clinical trial comparing simple drainage of anorectal abscess with and without fistula track treatment. Int J Colorectal Dis. 2003;18(2):107-110.
  • Schubert MC, Sridhar S, Schade RR, et al. What every gastroenterologist needs to know about common anorectal disorders. World J Gastroenterol. 2009;15(26):3201-3209.
  • Steele SR, Kumar R, Feingold DL, et al. Practice parameters for the management of perianal abscess and fistula-in-ano. Dis Colon Rectum. 2011;54(12):1465-1474.

SEE ALSO

Anorectal Fistula

CODES

ICD10

  • K61.2 Anorectal abscess
  • K61.3 Ischiorectal abscess
  • K61.4 Intrasphincteric abscess
  • K61.1 Rectal abscess
  • K61.0 Anal abscess

ICD9

566 Abscess of anal and rectal regions

SNOMED

  • anorectal abscess (disorder)
  • Ischiorectal abscess (disorder)
  • Intersphincteric abscess (disorder)
  • Supralevator abscess (disorder)
  • Anorectal fissure abscess (disorder)
  • Submucous anorectal abscess (disorder)

CLINICAL PEARLS

  • Anorectal abscess should be treated immediately.
  • Patients with systemic signs of infection or who are suspected of having complex abscesses require hospital admission and surgical consultation for treatment.
  • Most perirectal abscesses in infants and children do not require admission.
  • Incision and drainage with packing is the treatment of choice for perianal abscesses.
  • Ischiorectal and supralevator abscesses typically require drainage under general anesthesia.