Haemorrhoids
Engorgement and downward displacement of the normal vascular anal cushions that help maintain continence, so bleeding is bright and painless because the cushions themselves have no somatic sensory innervation above the dentate line.
In a nutshell
Haemorrhoids are the normal anal vascular cushions engorged and prolapsed by raised pressure from straining. Because the cushions lie above the dentate line, in insensate mucosa, bleeding is characteristically bright red and painless. Grading tracks the degree of prolapse and guides treatment tier.
Classic presentation
Painless bright red rectal bleeding coating the stool or on the toilet paper, with a sensation of prolapse after defecation, in a patient with a history of straining or constipation.
Key points
- Haemorrhoids are engorged anal cushions above the dentate line, not new lesions: this is why bleeding is painless (insensate mucosa) and bright red (arteriovenous supply).
- Grading I-IV tracks the degree of prolapse, from bulging into the lumen (I) to permanently prolapsed (IV), and directly determines treatment choice.
- Pain implies either thrombosis of an external component (below the dentate line, somatically innervated) or a coexisting anal fissure, not the haemorrhoid itself.
- Rubber band ligation works because it is applied above the dentate line, where it causes no pain, unlike the somatically sensitive skin below it.
- Bleeding mixed through the stool, a change in bowel habit, or anaemia should prompt exclusion of a more proximal or malignant cause before attributing bleeding to haemorrhoids.
First-line investigation
Digital rectal examination and proctoscopy, with colonoscopy reserved for red-flag features.
First-line management
Dietary fibre, fluids and avoidance of straining for all grades, escalating to rubber band ligation for persistent grade I-III disease.
Exam traps
- Do not attribute rectal bleeding to haemorrhoids in an older patient without first excluding colorectal cancer, especially if bleeding is mixed with stool or accompanied by a bowel habit change.
- Painless bleeding is the haemorrhoid pattern; pain points to thrombosis or a fissure, not the haemorrhoid itself: the exam uses pain as the discriminator between these diagnoses.
- Grade IV haemorrhoids are permanently prolapsed and cannot be manually reduced: do not confuse with grade III, which reduces manually.
- Banding is applied above the dentate line specifically because tissue there is insensate; applying it below the line onto somatically innervated skin would be exquisitely painful.
Educational content pending clinical review. Not medical advice.