Special Surgery 22. Anorectal Benign Diseases: Hemorrhoids, Perianal Fistula, Anal Fissure, Anorectal Abscesses

I. Hemorrhoids

Definition and Classification

• Hemorrhoids: symptomatic enlargement / prolapse of normal anal vascular cushions
• Internal hemorrhoids: above dentate line → visceral innervation → usually painless, bright red bleeding and prolapse

• Grade I: bleeding, no prolapse
• Grade II: prolapse with straining, reduces spontaneously
• Grade III: prolapse with straining, requires manual reduction
• Grade IV: permanently prolapsed / irreducible

• External hemorrhoids: below dentate line → somatic innervation → painful if thrombosed or inflamed

Etiology

• Risk factors: chronic constipation, excessive straining, low-fiber diet, obesity, pregnancy, heavy lifting, aging, prolonged toilet sitting

Clinical Features

• Bleeding: fresh bright red blood on paper, stool surface or dripping into toilet
• Palpable / prolapsing lump
• Itching, mucus discharge, soiling, discomfort
• Pain: mainly thrombosed external hemorrhoid, strangulated prolapse, fissure or abscess

Diagnosis

• Physical examination: inspection of perianal area → external hemorrhoids, thrombosis, prolapsed internal hemorrhoids, fissure/abscess/tumor differential
• DRE: assess mass, pain, sphincter tone, blood
• Anoscopy: best office test for internal hemorrhoids and distal rectum
• Colonoscopy / flexible sigmoidoscopy: if CRC screening age, alarm signs, anemia, changed bowel habit, weight loss, family history or atypical bleeding

Treatment

1. Conservative Therapy

• High-fiber diet / fiber supplementation, adequate fluids, stool softeners if needed
• Avoid straining and prolonged toilet sitting
• Weight loss, exercise, sitz baths / warm bathing
• Topical anesthetic or steroid cream: short-term symptom relief only

2. Office Procedures: Mainly Grade I-II, Selected Grade III

• Rubber band ligation: most common office method, placed above dentate line
• Sclerotherapy: irritant / sclerosant injection
• Infrared coagulation: smaller bleeding internal hemorrhoids

3. Surgical Therapy: Grade III-IV, Complicated or Failed Office Treatment

• Excisional hemorrhoidectomy: most definitive, more postoperative pain

• Milligan-Morgan: open hemorrhoidectomy
• Ferguson: closed hemorrhoidectomy

• Stapled hemorrhoidopexy: internal circumferential prolapse; not for large external hemorrhoids
• Doppler-guided hemorrhoidal artery ligation / THD: reduces inflow, can be combined with mucopexy
• Thrombosed external hemorrhoid: excision can be considered early if severe pain

II. Perianal Fistula

Definition and Etiology

• Perianal fistula / fistula-in-ano: abnormal tract between anal canal/rectum and perianal skin
• Usually follows anorectal abscess → cryptoglandular origin
• Other causes: Crohn disease, TB, radiation proctitis, malignancy, trauma, previous surgery
• Main surgical principle: close the fistula while preserving continence

Parks Classification

• Intersphincteric: between internal and external sphincter, most common
• Transsphincteric: passes through internal and external sphincters into ischioanal fossa
• Suprasphincteric: loops above puborectalis, then descends through levator ani
• Extrasphincteric: bypasses sphincter complex from rectum to perianal skin

Goodsall Rule

• External opening posterior to transverse anal line → curved tract to posterior midline internal opening
• External opening anterior to transverse anal line → usually straight radial tract to nearest anal crypt
• Exception: anterior opening >3 cm from anal verge may still curve posteriorly
• Approximate rule only → MRI / EUA defines complex anatomy

Clinical Features

• Persistent or recurrent purulent discharge from perianal opening
• Intermittent pain, swelling, recurrent abscess, skin irritation, itching

Diagnosis

• Inspection + DRE: external opening, induration, internal opening if possible
• Anoscopy / proctoscopy: internal opening and proctitis
• MRI pelvis or endoanal ultrasound: complex, high or recurrent fistula
• Examination under anesthesia: mapping + treatment if needed
• Consider IBD workup if multiple fistulas, recurrent disease, diarrhea or Crohn suspicion

Treatment

1. Simple / Low Fistula

• Fistulotomy: lay open tract; high healing rate if little sphincter is divided
• Fistulectomy: tract excision; larger wound, less commonly preferred for simple disease

2. Complex / High Fistula

• Drain sepsis first
• Loose seton: maintains drainage, prevents abscess recurrence, preserves sphincter
• Sphincter-sparing options: LIFT, endorectal advancement flap, selected plugs/glue/laser/video-assisted techniques
• Cutting seton: selected cases only because continence risk is higher

3. Crohn-Associated Fistula

• Combined surgical + medical treatment
• Drain abscess and place loose seton if needed
• Control rectal inflammation with biologic therapy, commonly anti-TNF
• Avoid aggressive sphincter division if proctitis or complex fistula is present

III. Anal Fissure

Definition, Etiology and Types

• Anal fissure: longitudinal tear in anoderm / anal canal mucosa, typically posterior midline
• Etiology: hard stool, constipation, prolonged diarrhea, anal intercourse/trauma, childbirth
• Pathogenesis of chronic fissure: internal sphincter hypertonia → local ischemia → non-healing tear
• Acute fissure: <6 weeks, superficial fresh tear
• Chronic fissure: >6 weeks, sentinel skin tag, hypertrophied anal papilla, exposed internal sphincter fibers
• Lateral / multiple / atypical fissures: suspect Crohn disease, TB, HIV, syphilis, malignancy or trauma

Clinical Features

• Severe sharp / stabbing pain during defecation
• Pain can persist minutes-hours after stool
• Fresh bright red bleeding on paper or stool surface
• Internal sphincter spasm → fear of defecation → constipation → worse fissure

Diagnosis

• Typical history + gentle inspection by separating buttocks
• DRE / anoscopy: very painful, often deferred until pain improves
• EUA: unclear diagnosis, severe pain prevents exam, abscess suspected or atypical lesion

Treatment

1. Conservative Therapy

• High-fiber diet, fiber supplements, fluids, stool softeners
• Warm sitz baths
• Topical anesthetic: short-term pain relief

2. Chemical Sphincterotomy

• Topical nitroglycerin / glyceryl trinitrate: relaxes internal sphincter; headache common
• Topical calcium channel blocker: diltiazem or nifedipine, often better tolerated
• Botulinum toxin injection: temporary internal sphincter relaxation

3. Surgical Therapy

• Lateral internal sphincterotomy: gold standard for chronic fissure refractory to medical therapy
• Principle: divide part of internal anal sphincter → lower resting pressure → healing
• Risk: flatus/fecal incontinence, especially baseline sphincter weakness, obstetric injury or diarrhea
• Advancement flap: selected patients with high incontinence risk

IV. Anorectal Abscesses

Definition and Etiology

• Anorectal abscess: pus collection in perianal or perirectal space
• Most common cause: cryptoglandular infection of anal glands
• Bacteria: mixed aerobic/anaerobic flora, e.g. E. coli, Gram-positive organisms, Bacteroides
• Other causes/risk factors: Crohn disease, trauma, anal fissure, immunosuppression, diabetes, HIV, malignancy or radiation injury

Classification

1. Perianal abscess: most common, superficial near anal verge
2. Ischiorectal / ischioanal abscess: deeper lateral space, buttock swelling
3. Intersphincteric abscess: between internal and external sphincters
4. Supralevator abscess: above levator ani, deep pelvic pain/systemic illness
5. Submucosal abscess: under rectal/anal mucosa

Clinical Features

• Sudden severe perianal / rectal pain
• Perianal swelling, redness, cellulitis, tender fluctuant mass if superficial
• Fever, malaise, tachycardia or systemic toxicity if severe
• Purulent discharge if spontaneously draining
• Deep abscess: rectal pain, urinary retention, fever with minimal external signs

Diagnosis

• Clinical examination is enough for most superficial perianal abscesses
• Inspection + gentle DRE if tolerable; anoscopy only if pain allows
• MRI pelvis, CT or endoanal ultrasound: deep, recurrent, complex, Crohn-related, immunosuppressed or atypical cases
• EUA: severe pain, deep abscess, unclear anatomy or operative drainage

Treatment

• Prompt surgical incision and drainage = gold standard
• Do not treat routine abscess with antibiotics alone
• Drainage principles: incision close to anal verge, adequate drainage, break loculations, avoid sphincter injury
• Antibiotics only as adjunct if cellulitis, systemic signs/sepsis, immunosuppression, diabetes or significant comorbidity
• Follow-up: fistula can develop after abscess in a substantial proportion of patients
• Primary fistulotomy during abscess drainage: only selected simple low fistula with clear anatomy and low continence risk