How can you differentiate between an internal and external hemorrhoid?

Differentiating Between Internal and External Hemorrhoids

Hemorrhoids are definitively classified as internal or external based on their anatomical location relative to the dentate line, with internal hemorrhoids located above the dentate line and external hemorrhoids located below it. 1, 2

Anatomical Differences

• Internal hemorrhoids:

  • Located above (proximal to) the dentate line
  • Covered by rectal mucosa
  • Not visible during external examination
  • Require anoscopy for proper visualization
  • Typically painless due to visceral innervation
  • Classified into four degrees based on prolapse:
    • First-degree: Bleeding without prolapse
    • Second-degree: Prolapse during defecation with spontaneous reduction
    • Third-degree: Prolapse requiring manual reduction
    • Fourth-degree: Irreducible prolapse

• External hemorrhoids:

  • Located below (distal to) the dentate line
  • Covered by anoderm and perianal skin
  • Visible during external examination
  • Do not require special instruments to visualize
  • Can be painful due to somatic innervation
  • Usually asymptomatic unless thrombosed

Clinical Presentation

Internal Hemorrhoids

• Primary symptom: Painless bright red bleeding
• Blood typically appears as scanty blood on toilet paper or dripping/squirting into toilet bowl
• May present with mucus discharge
• Prolapse may occur depending on degree
• Generally painless unless complicated by thrombosis or strangulation

External Hemorrhoids

• Usually asymptomatic unless thrombosed
• When thrombosed: acute onset of pain and a visible perianal lump
• May cause hygiene issues when large
• Thrombosis may lead to bleeding if local pressure causes skin erosion
• Pain is the hallmark symptom of thrombosed external hemorrhoids 1, 2

Physical Examination Findings

For External Hemorrhoids:

• Visible bluish lumps covered by perianal skin
• Located outside the anal canal
• Can be seen without special instruments
• When thrombosed, appear as tense, painful, purplish nodules
• May have associated skin tags from previous episodes

For Internal Hemorrhoids:

• Not visible on external examination unless prolapsed
• Require anoscopy with adequate light source for proper visualization
• Appear as reddish bulging tissue within the anal canal
• When prolapsed, appear as protrusions of rectal mucosa

Common Diagnostic Pitfalls

1. Misattribution of symptoms: Many anorectal symptoms are incorrectly attributed to hemorrhoids when other pathologies may be present 2

2. Incomplete evaluation: Relying solely on patient descriptions without proper examination can lead to misdiagnosis 1

3. Failure to recognize concurrent conditions: Up to 20% of hemorrhoid patients have concurrent anal fissures 1, 2

4. Confusing rectal varices with hemorrhoids: Portal hypertension can cause varices of the anal canal, which are distinct from hemorrhoids and require different treatment 1

5. Overlooking more serious conditions: Bright red rectal bleeding requires at minimum anoscopy and flexible sigmoidoscopy to rule out other sources 1

Remember that a thorough anorectal examination, including anoscopy, is essential for accurate diagnosis of hemorrhoids, as symptoms alone are not specific enough for definitive diagnosis 1.