Important for medical students (both UG and PG) and clinicians. Detailed slide on anal canal anatomy, haemorrhoids pathophysiology, diagnosis, aetiology and management.

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2. Anatomy of Anal Canal
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3. Anatomy of Anal Canal
Anal cushions
• thickened anal mucosa that consist of arteriovenous blood vessels,
smooth muscle (e.g., Treitz muscle), and fibroelastic tissue (e.g. collagen,
elastic fibers)
• Located at 11, 7 and 3 o'clock in the lithotomy position
• Play an important role in maintaining continence by enabling tight
closure of the rectum
Anal Columns
• longitudinal folds of mucous membrane that are fused at their inferior
ends by transverse folds (anal valves)
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5. Anal Sinuses
• small, mucus-secreting pouches between the anal columns above the anal
valves
Dentate Line
• Circular separation line formed by the fusion of anal valves
• Divides anal canal into an upper and lower part
External Anal Sphincter
• Surrounds lower third of anal canal
• Consists of skeletal muscle; functions to open & close the anal canal and
opening
• Innervated by the pudendal nerve and under voluntary control
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6. Internal anal sphincter
• Surrounds upper two-thirds of anal canal
• Consists of involuntary circular smooth muscle and is responsible for
85% of the resting pressure of the anal canal
• Innervated by the enteric nervous system
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8. Blood Supply
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Fig. Pelvis with blood supply of the anal canal

10. Hemorrhoids (aka Piles)
• arise from a cushion of dilated arteriovenous blood vessels and
connective tissue in the anal canal that may abnormally enlarge or
protrude
• Divided into three categories:
 internal (above the dentate line)
 external (below the dentate line)
 mixed (above and below the dentate line)
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11. Etiology
• Excessive straining (e.g., from chronic constipation, frequent bowel
movements, chronic cough, heavy lifting, benign prostatic hyperplasia)
• Decreased venous return
• Extended periods of sitting (e.g., due to occupation or sedentary lifestyle)
• Connective tissue disorder (e.g., Ehlers-Danlos syndrome, scleroderma)
• Pregnancy
• Portal hypertension and anorectal varices
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12. Other Risk Factors
• Familial tendency
• Higher socioeconomic status
• Chronic diarrhea
• Colonic malignancy
• Hepatic diseases
• Obesity
• Elevated anal resting pressure
• Spinal cord injury
• Loss of rectal muscle tone
• Rectal surgery
• Episiotomy
• Anal intercourse
• IBDs
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13. Classification
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Internal hemorrhoids:
External hemorrhoids: no widely used classification system used.

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Fig. Grade II internal hemorrhoids
Fig. Grade III internal hemorrhoids

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Fig. Grade IV internal hemorrhoids

17. Internal Hemorrhoids
• Prolapse of internal hemorrhoids, with possible incarceration and
strangulation, may cause pain by triggering an anal sphincter complex
spasm → possible ischemia and necrosis of internal hemorrhoids →
worsening anal sphincter complex spasm → potential external
hemorrhoid thrombosis → cutaneous pain
• Develop above the dentate line, which is not innervated by cutaneous
nerves; distension does not cause pain.
• Bleeding and/or prolapsed internal hemorrhoids irritate sensitive
perianal skin → perianal itching
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18. External Hemorrhoids
• Develop below the dentate line, which is innervated by cutaneous
nerves; distention of this innervated skin due to a clot or edema results
in severe pain.
• Acute thrombosis triggers cutaneous pain, lasting 7–14 days →
thrombosis resolves → residual skin or skin tags of distended anal skin
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19. Clinical Features
Internal Hemorrhoids
• Often painless, bright red bleeding at the end of defecation (potentially
dull, aching pain with severe sphincter spasm)
• Perianal mass in the event of prolapse
• Pruritus
• Discharge (containing mucus or fecal debris)
• Ulceration (in grade IV)
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20. External Hemorrhoids
• Painful perianal mass
• Pruritus
Clinical Examination
• Inspect perianal area for external hemorrhoids and prolapsed internal
hemorrhoids; exclude other conditions (e.g., anal skin tags, polyps).
• Digital rectal examination may show abnormal masses or tenderness or
bleeding.
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21. Diagnosis
• Digital rectal examination
• Anoscopy
 For assessing the anus and distal rectum
 Useful when hemorrhoids are suspected but rectal examination is inconclusive
 In addition, proctoscopy may be used to support anoscopy findings
• Other procedures
 Flexible sigmoidoscopy, colonoscopy, or barium enema: to exclude suspected
malignancy
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22. Differential Diagnosis
• Anal skin tags: folds of skin at the
anal verge, often at 12 o'clock in
the lithotomy position (benign, but
may become inflamed or itch)
• Hypertrophied anal papillae
• Polyps
• Anal and colorectal carcinoma
• Anal fissures
• Anorectal varices
• Proctitis
• Condyloma acuminata
• Inflammatory bowel disease (often
associated with anal fistulas and
abscesses)
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23. Treatment
• Conservative treatment
• Outpatient treatment
• Surgical treatment
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24. Conservative Treatment
• Indications: grade I–II internal hemorrhoids and external hemorrhoids
• Interventions:
 Lifestyle modifications: weight loss, exercise, high fiber diet, avoid fatty and
spicy foods, increase water intake
 Alter stool habits (e.g., avoid excessive straining or > 5 min periods on the toilet)
 Sitz baths
 Stool softeners (e.g., docusate)
 Topical or suppository analgesia (e.g., lidocaine)
 Topical anti-inflammatory (e.g., hydrocortisone, especially with pruritus, but no
longer than 1 week)
 Topical antispasmodic agents (e.g., nitroglycerin)
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25. Outpatient Treatment
• Indications: all internal hemorrhoids with symptoms persisting
despite conservative treatment and grade III internal hemorrhoids
• Interventions:
• Rubber band ligation (RBL)
• Sclerotherapy
• Infrared coagulation
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26. Surgical Treatment
• Indications: grade IV internal hemorrhoids and no improvement of
condition after clinical interventions
• Interventions
 Arterial ligation of hemorrhoids (HAL)
 Submucosal hemorrhoidectomy
 Ferguson approach (closed approach)
 Milligan-Morgan approach (open approach)
 Stapled hemorrhoidopexy (e.g., using the Longo procedure): only effective
for internal hemorrhoids
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27. Complications
• Internal: prolapse of internal hemorrhoid → accumulation of mucus and
fecal debris in external anal tissue → local irritation and inflammation
• External: may become acutely thrombosed (e.g., with excessive
straining) → necrosis of overlying skin and bleeding
• Postoperative
 Pain
 Thrombosis
 Bleeding
 Perianal/pelvic sepsis
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28. Prevention
• Eat high-fiber diet
• Drink plenty of fluids
• Fiber supplements
• Don’t strain
• Go as soon as you feel the urge
• Exercise
• Avoid long period of sitting
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