• Clinical science

Thrombosed external hemorrhoid

Abstract

A thrombosed external hemorrhoid is a localized thrombosis of the inferior hemorrhoidal venous plexus that results in severe, acute anal pain. Perianal clinical examination reveals a bulging, purplish nodule that is very tender to palpation. It may be treated conservatively with analgesic creams and steroids or be surgically excised for immediate pain relief.

Definition

External hemorrhoids are located distal to the dentate (pectinate) line; and are drained by the inferior hemorrhoidal (rectal) plexus. External hemorrhoid thrombosis occurs if a clot forms in the inferior hemorrhoidal plexus.

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Etiology

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Pathophysiology

  • Acute distention blood vessels → pooling of the blood → thrombus formation → inflammation and distention of the overlying perianal skin → severe pain

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Clinical features

  • Acute onset of severe pain
  • Pain with defecation
  • May ulcerate and bleed
  • Thrombosed hemorrhoid detectable on rectal exam: palpable, bulging, dark red to purplish nodule at the outer rim of the anal canal; very tender to palpation

If the patient also presents with systemic symptoms such as weight loss, night sweats, or abdominal pain, underlying malignancy or infection must be ruled out!

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Differential diagnoses

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The differential diagnoses listed here are not exhaustive.

Treatment

Conservative

  • Indications: small thromboses , thromboses older than 72 hours, current pregnancy
  • Treatment
  • Thromboses usually resolve or improve within 2–3 days. Surgery is rarely required.

Surgical

  • Indications
    • Thrombosis with acute severe pain within 72 hours of onset → rapid pain relief
    • Symptoms refractory to conservative treatment
    • Combination of both internal and external hemorrhoids
  • Treatment
  • Complications (rare): recurrence requiring further surgery, local swelling, minor bleeding, perianal fistula or abscess

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