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Perirectal Abscess, Emergency Medicine

Basics

Description

- Ischiorectal: - Large potential space - May become very large before diagnosed - Can communicate posteriorly with other side forming "horseshoe " abscess

- Bacterial cause is typically a mix of stool pathogens: - Associated diseases: - Diabetes - Inflammatory bowel disease - Malignancy - Immunocompromised host

- Delayed drainage may worsen outcome - Bedside drainage: - Only if localized perianal abscess - Probe to rule out deeper tract

- Radial incision close to anal verge - Explore cavity, breaking any loculations. - Irrigate liberally. - Loose packing removed at 48 hr.

- Postoperative care: - Sitz baths TID 24 hr after I&D - High-fiber diet or bulking agent - Analgesic

Localized infection and accumulation of purulent material adjacent to anus or rectum

Etiology

  • Anal crypt gland infection, with spread to adjacent areas separated by muscle and fascia:Perianal:Most commonUsually with red bulge near anusIschiorectal:Large potential spaceMay become very large before diagnosedCan communicate posteriorly with other side forming "horseshoe " abscessIntersphincteric:Contained at primary site of origin between internal and external sphinctersSupralevator:Very deep above levator aniNeeds operative debridement under general anesthesiaOften systemic symptoms before diagnosis is made
  • Bacterial cause is typically a mix of stool pathogens:
  • Associated diseases:DiabetesInflammatory bowel diseaseMalignancyImmunocompromised host

Diagnosis

Signs and Symptoms

  • Pain: Perianal, rectal, or pelvic
  • Swelling, fluctuance, drainage, fever

History

  • Perianal pain:Aggravated by defecation, sitting, coughing
  • Dull deep pelvic or rectal pain:Less pain if arises above dentate line (ischiorectal and supralevator)
  • Rectal or perirectal drainage
  • Fever/chills
  • Constipation

Physical Exam

  • Perianal swelling, erythema, induration, fluctuance, tenderness
  • Inner cleft buttock abscess = red flagRectal abscess can track out to buttock
  • Rectal exam is the most important diagnostic interventionRectal swelling or tendernessFistula can be probed, or palpated as a cord

Essential Workup

  • Careful history and physical exam with rectal exam are paramount in making diagnosis.
  • Have high index of suspicion for any constant perirectal pain.

Diagnosis Tests & Interpretation

No labs or imaging routinely indicated

Lab

  • CBC: Leukocytosis with left shift
  • Wound culture: Not typically indicated
  • Blood cultures: Mainly for sepsis

Imaging

  • CT (with IV contrast, +/ " PO contrast)
  • MRI (helpful with detecting fistulas)
  • Endoanal US sometimes used

Diagnostic Procedures/Surgery

Incision and drainage (I&D) is the definitive management.

Differential Diagnosis

  • Anal fissure
  • Sentinel pile in the posterior midline or anterior midline
  • Thrombosed or inflamed hemorrhoids
  • Anal ulcer (i.e., HIV)
  • Proctitis (i.e., gonococcal)
  • Anorectal carcinoma

Treatment

Initial Stabilization/Therapy

Pain medication

Ed Treatment/Procedures

  • Delayed drainage may worsen outcome
  • Bedside drainage:Only if localized perianal abscessProbe to rule out deeper tractRadial incision close to anal vergeExplore cavity, breaking any loculations.Irrigate liberally.Loose packing removed at 48 hr.
  • Operative debridement under general anesthesia:If local anesthesia is inadequate, or deeper abscess
  • Antibiotics rarely necessary:Extensive cellulitisImmunosuppressionValvular heart diseaseSystemic infectionProsthetic devicePO:Amoxicillin clavulanate or fluoroquinoloneConsider MRSA coverageIV:CefoxitinAmpicillin sulbactamCombination therapy with ampicillin, gentamicin, and clindamycin or metronidazole
  • Postoperative care:Sitz baths TID 24 hr after I&DHigh-fiber diet or bulking agentAnalgesic

Medication

  • Amoxicillin clavulanate: 875 mg PO q12h or 500 mg PO q8h
  • Ampicillin sulbactam: 1.5 " 3 g IV q6h
  • Cefoxitin: 1 " 2 g IV q6 " 8h
  • Clindamycin: 600 " 900 mg IV div. q8h
  • Gentamicin: 3 " 6 mg/kg/d IV div. q8h
  • Metronidazole: 7.5 mg/kg IV q6h

Follow-Up

Disposition

Admission Criteria

  • Need for operative drainage
  • Systemic toxicity/signs of sepsis

Discharge Criteria

Adequate I&D with complete drainage

Issues for Referral

All should be referred to surgeon in 24 " 48 hr

Followup Recommendations

Surgeon referral within 24 " 48 hr to evaluate for fistula:

  • Fistulas develop in 25 " 50% of anorectal abscesses.

Pearls and Pitfalls

  • Be certain of extent of abscess:Thorough rectal exam and probing is mandatory.Imaging adds insight into deeper areas not accessible to exam
  • Deeper abscesses above dentate line have less pain and can present with isolated fever

Additional Reading

  • Marcus RH, Stine RJ, Cohen, MA. Perirectal abscess. Ann Emerg Med. 1995;25(5):597 " 603.
  • Rizzo JA, Naig AL, Johnson EK. Anorectal abscess and fistula-in-ano: Evidence-based management. Surg Clin North Am. 2010;90(1):45 " 68.
  • Schubert MC, Sridhar S, Schade RR, et al. What every gastroenterologist needs to know about common anorectal disorders. World J Gastroenterol. 2009;15:3201 " 3209.
  • Steele SR, Kumar R, Feingold DL, et al. Practice parameters for the treatment of perianal abscess and fistula-in-ano. Dis Colon Rectum. 2011;54:1465 " 1474.

See Also (Topic, Algorithm, Electronic Media Element)

  • Abscess
  • Anal Fissure
  • Hemorrhoid

Codes

ICD9

  • 565.1 Anal fistula
  • 566 Abscess of anal and rectal regions

ICD10

  • K61.0 Anal abscess
  • K61.1 Rectal abscess
  • K61.3 Ischiorectal abscess
  • K60.4 Rectal fistula

SNOMED

  • 91669008 Perirectal abscess (disorder)
  • 36046008 Ischiorectal abscess (disorder)
  • 82127005 perianal abscess (disorder)
  • 235795007 Intersphincteric abscess (disorder)
  • 197163002 Supralevator abscess (disorder)
  • 286977005 Ischiorectal abscess/fistula (disorder)