Anorectal procedures

🗺️ Anatomy - The Back Passage Basics

• Anal Canal: ~4 cm long, from anorectal ring to anal verge.
• Sphincters:
  • Internal (IAS): Involuntary, smooth muscle (autonomic).
  • External (EAS): Voluntary, striated muscle (Pudendal n. S2-S4). 📌 S2,3,4 keeps the poop off the floor.
• Dentate (Pectinate) Line: Critical anatomical landmark.
  • Above: Columnar epithelium, visceral innervation (painless), superior rectal a./v. (portal drainage), internal iliac nodes.
  • Below: Squamous epithelium, somatic innervation (painful), inferior rectal a./v. (caval drainage), superficial inguinal nodes.

⭐ The dentate line dictates symptoms and metastatic spread. Lesions above are typically painless with drainage to internal iliac nodes; lesions below are painful and drain to superficial inguinal nodes.

🩺 Pathology - Common Anal Woes

• Hemorrhoids: Dilated submucosal vessels. Risks: straining, constipation, pregnancy.

  Type	Location	Innervation	Symptoms
  Internal	Above dentate line	Visceral (ANS)	Painless, bright red bleeding, prolapse
  External	Below dentate line	Somatic	Painful, pruritus; severe pain if thrombosed

• Anal Fissure: Longitudinal tear in anoderm, distal to dentate line.

  • 90% at posterior midline (↓ blood flow).
  • Severe, tearing pain with defecation; blood on tissue.
  • Chronic triad: fissure, sentinel pile (skin tag), hypertrophied anal papilla.

  ⭐ An anal fissure located off the midline (e.g., lateral) is a red flag for underlying pathology like Crohn's disease, HIV, TB, or malignancy.

• Anorectal Abscess & Fistula:

  • 📌 Goodsall's Rule: Anterior-opening fistulas track straight; posterior-opening fistulas track in a curved path to the posterior midline.

✂️ Clinical - Snips, Bands, and Drains

• Hemorrhoids (Bands): Rubber Band Ligation (RBL)

  • Indication: Symptomatic internal hemorrhoids (Grades I-III).
  • Procedure: An elastic band is placed at the base of the hemorrhoid (above the dentate line) → ischemic necrosis → sloughing in 7-10 days.
  • Complications: Pain (if placed too low), bleeding, thrombosis, pelvic sepsis (rare).

• Anal Fissure (Snips): Lateral Internal Sphincterotomy (LIS)

  • Indication: Chronic anal fissure refractory to medical management (e.g., nifedipine, diltiazem).
  • Procedure: Controlled division of the internal anal sphincter to ↓ resting pressure and ↑ blood flow, promoting healing.
  • Complication: Minor fecal incontinence (flatus > stool) in up to 5% of patients.

• Anorectal Abscess (Drains): Incision & Drainage (I&D)

  • Indication: Acutely painful, fluctuant perianal/ischiorectal mass.
  • Procedure: Urgent drainage, often with a cruciate incision.
  • Sequela: High rate (~50%) of subsequent fistula-in-ano formation.

⭐ Post-hemorrhoidectomy urinary retention is the most common immediate complication. Severe, deep-seated pain days later suggests an evolving abscess or pelvic sepsis.

Hemorrhoid Management Algorithm

⚡ Biggest Takeaways

• Anal fissures failing medical therapy need lateral internal sphincterotomy (risk: incontinence).
• Excise thrombosed external hemorrhoids if <72 hours; use rubber band ligation for internal hemorrhoids.
• Anorectal abscesses require prompt incision and drainage; they often precede a fistula-in-ano.
• Treat simple fistulas with fistulotomy; use a Seton for complex cases (Crohn's, high) to preserve sphincter function.
• Full-thickness rectal prolapse (concentric rings) requires surgical rectopexy.
• Pilonidal abscess needs I&D; chronic disease requires excision of sinus tracts.