• Clinical science



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Physiological hemorrhoids are arteriovenous cushions within the rectal corpus cavernosum, which may become pathological hemorrhoids following abnormal enlargement and possible protrusion. Hemorrhoids are divided into three categories: internal (above the dentate line), external (below the dentate line), or mixed (above and below the dentate line). Individuals at higher risk of contracting hemorrhoids are typically above the age of 45, have constipation or connective tissue disorders, or engage in activities that require prolonged sitting. The patient may present with rectal bleeding, pain, prolapse, and pruritus. The diagnosis of hemorrhoids involves careful inspection of the anal area during clinical examination, especially when the patient increases intra‑abdominal pressure by straining. Anoscopy and proctoscopy may be necessary to confirm the diagnosis. Internal hemorrhoids are classified into four grades, depending upon the extent of prolapse: Conservative management is recommended in grades I or II (anal hygiene, anti‑inflammatory ointments), while surgical intervention is indicated in grades III or IV (e.g., Milligan‑Morgan hemorrhoidectomy).


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Internal hemorrhoids

Grade Palpation Findings
I Hemorrhoids are not prolapsed (only projected into the anal canal); above the dentate line; reversible; often bleed
II Prolapse when straining, but hemorrhoids spontaneously reduce at rest
III Prolapse when straining; hemorrhoids only reducible manually
IV Irreducible prolapse; hemorrhoids may be strangulated and thrombosed with possible ulceration



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Anatomy of the anal canal

Structure Characteristics
Anal cushions
  • Thickenings of the anal mucosa
    • Specialized structures comprised of blood vessels, (e.g., arteriovenous), smooth muscle (e.g., Treitz's muscle), and fibroelastic (e.g., collagen, elastic fibers) tissue.
  • Located on the right anterior, right posterior, and left lateral position (3, 7 and 11 o'clock in the lithotomy position)
  • Play an important role in maintaining tight closure of the rectum and continence
  • Defecation causes contraction of supportive structures (e.g., Treitz's muscle) → compression of anal cushions → increased diameter of the anal canal for adequate passage of stool.
Anal columns
  • Folds of mucous membrane formed by anal cushions (arterial cavernous bodies) in the submucosa
Anal valves
  • Transverse folds that connect the distal end of the anal columns
Crypts of Morgagni
Pectinate line

Regional differences of the anal canal

Above the pectinate line Below the pectinate line
Embryological origin

Arterial supply

Venous drainage
  • Venous drainage: external hemorrhoidal plexus → inferior rectal vein (drains into the internal pudendal veininternal iliac vein → common iliac vein → inferior vena cava)
Lymphatic drainage


Hemorrhoids are engorgements of the corpus cavernosum recti, which are arteriovenous structures above the pectinate line. The corpus cavernosum recti function to help maintain continence. They drain into the superior or inferior hemorrhoidal veins.

The pathophysiology of hemorrhoids is not very clear, and multiple theories exist regarding their origin.

  • "Sliding anal canal" theory
    • Widely accepted theory
    • Degeneration of supportive fibroelastic tissue → abnormal downward displacement of anal cushions (prolapse) → venous engorgement and enlargement of the cushions
  • Other theories
    • Inadequate compression of anal cushions during defecation → venous engorgement
    • Anorectal bowel obstruction (e.g., caused by stool masses, inflammation) → increased pressure on the rectal corpus cavernosum (arteriovenous obstruction) → hyperplasia → increased tone in the anal sphincter complex→ further obstruction → repetitive cycle of worsening obstruction and arteriovenous cushion hyperplasia

Internal vs. external hemorrhoids

Hemorrhoids are classified as internal , external or mixed .

Hemorrhoids are not varicose veins (= widening of the veins)! However, anorectal varices do exist, e.g., following portal hypertension! The terms anorectal varices and hemorrhoids are often used interchangeably, but this is incorrect!


Clinical features

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Hemorrhoids are a clinical diagnosis!


  • 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 (especially in patients over the age of 40)


Differential diagnoses

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Always consider the possibility of a concurrent colorectal carcinoma!


The differential diagnoses listed here are not exhaustive.


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Hemorrhoids should only be treated in a symptomatic patient!

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), but NSAIDS should be avoided
    • Topical antispasmodic agents (e.g., nitroglycerin)

Outpatient treatment

  • Indications: all internal hemorrhoids with persistent symptoms despite conservative treatment or grade III internal hemorrhoids
  • Interventions
    • Rubber band ligation (RBL)
    • Sclerotherapy
    • Infrared coagulation

Surgical treatment (stages III–IV)



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Hemorrhoid disease

  • Internal: Mucous and fecal debris deposited by prolapsed internal hemorrhoids onto external anal tissue causes local irritation and inflammation.
  • External: may become acutely thrombosed (e.g., with excessive straining) → necrosis of overlying skin → bleeding



We list the most important complications. The selection is not exhaustive.