ANORECTAL ABSCESS

ANORECTAL ABSCESS - Timothy L. Black, MD
BASICS
DESCRIPTION
• Localized induration and fluctuance due to inflammation of the soft tissue near the rectum or anus
• 80% are perianal, the remainder are intrasphincteric or supra-levator (1)[C]
• System(s) Affected: Gastrointestinal; Skin/Exocrine
ALERT
Geriatric Considerations
A high pelvirectal abscess may cause no symptoms except lower abdominal pain and fever.
Pediatric Considerations
Common in first year of life
GENERAL PREVENTION
• Avoid constipation.
• Don't use enemas.
• Avoid rectal temperatures or medicines in immunocompromised patients.
EPIDEMIOLOGY
• Predominant age: All ages (most common in infants) (2)[C]
• Predominant sex: Male > Female (4:1)
Incidence
Common
RISK FACTORS
• Inciting trauma
- Injections for internal hemorrhoids
- Enema tip abrasions
- Puncture wounds from eggshells or fish bones
- Foreign objects
- Prolapsed hemorrhoid
• Inflammatory bowel disease
• Chronic granulomatous disease
• Immunodeficiency disorders
• Hematologic malignancies (5-8% of these patients will have abscess at some time)
• Diabetes
• Chronic medical immunosuppression
ETIOLOGY
• 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
• Organisms (usually mixed):
- Escherichia coli
- Proteus vulgaris
- Streptococci
- Staphylococci
- Bacteroides
- Pseudomonas aeruginosa
ASSOCIATED CONDITIONS
• Crohn's disease
• Other inflammatory disease (e.g., appendicitis, salpingitis, diverticulitis)
• Possibly perianal hidradenitis suppurativa, or HIV infection in patients with recurring perianal or ischiorectal abscesses

DIAGNOSIS
SIGNS AND SYMPTOMS
• Perirectal swelling for superficial abscesses
• Perirectal redness
• Perirectal tenderness
• Perirectal throbbing pain
• Fever and other toxic symptoms with deep abscesses
• If abscess is not accompanied by external swelling, digital rectal exam will reveal a swollen tender mass.
• Pain on defecation
Physical Exam
Digital rectal examination is mandatory
TESTS
Lab
Complete blood count: Leukocytosis
Imaging
• Barium enema (rarely needed)
• CT scan of pelvis and perineum indicated if horseshoe or ischiorectal abscess suspected (3)[C]
Diagnostic Procedures/Surgery
Only indicated if diagnosis in doubt
• Sigmoidoscopy: Rule out unusual causes
• Proctoscopy: Redness, induration of anus; tender mass
Pathological Findings
• Inflammation of anal mucosa
• Pus
• Inflammatory tissue
DIFFERENTIAL DIAGNOSIS
• Carcinoma
• Retrorectal tumors
• Crohn's disease
• Primary lesions of syphilis
• Tuberculous ulceration
TREATMENT
GENERAL MEASURES
Appropriate health care
• Outpatient surgery with oral antibiotics (although in some cases, antibiotics may not be necessary) (4)[B]
• Inpatient surgery with IV antibiotics for supra-levator abscess or toxicity (3)[C]
Diet
Increase fiber and fluid intake.
Activity
Resume work and normal activity as soon as possible.
MEDICATION (DRUGS)
• Antibiotics
• Stool-softening laxatives
• Contraindications
- Refer to manufacturer's literature
• Precautions
- Refer to manufacturer's literature
• Significant possible interactions
- Refer to manufacturer's literature
SURGERY
• Perianal abscess
- Incise and drain abscess (4)[B]
- Local anesthetic frequently appropriate
- Pack wound with Iodoform gauze (24-48 hours).
• Ischiorectal abscess
- Incise and drain abscess (4)[B]
- 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.
• Supralevator abscess
- Incise and drain abscess into lower rectum or anal canal (3)[C]
- General anesthesia required
• After surgery
- Sitz baths q2-4h
- Heating pad, heat lamp, or warm compress as needed for pain
- Encourage moving legs as soon as possible
- Prevent constipation.
FOLLOW-UP
PROGNOSIS
• Slow healing depending on extent of disease and concurrent illnesses, complete healing by 6 months if no complications
• Healing in infants may be complete in 1-3 weeks.
• Drainage alone results in cure rate of 50% or more.
COMPLICATIONS
• Possible anorectal fistula (in 25% of patients) (2,3)[C]
• Possible rectovaginal fistula
• Fecal incontinence due to rupture through sphincter muscle
• Recurrence of abscess if underlying cause not corrected
• Necrotizing infection with rapid progression, sepsis, and death (3)[C]
PATIENT MONITORING
Routine postoperative care with attention to wound healing, which should progress from the inside out
REFERENCES
1. Fazio VW. Anorectal disorders. In: Gastroenterology Clinics of North America. Philadelphia: Saunders; 1987.
2. Ziegler M, Azizkhan R, Weber T, et al., eds. Operative Pediatric Surgery. New York: McGraw-Hill, 2003
3. Townsend C, Beauchamp RD, Evers BM, et al. eds. Sabiston Textbook of Surgery, 17 ed. Philadelphia: Elsevier Saunders, 2006
4. Whiteford MH, Kilkenny J, Hyman N, et al. Practice parameters for the treatment of perianal abscess and fistula-in-ano (revised). Dis Colon Rectum 2005;48:1337-1342.