What causes hemorrhoids?

Causes of Hemorrhoids

Hemorrhoids are primarily caused by increased pressure in the anal canal that leads to abnormal swelling of the anal cushions, stretching of suspensory muscles, and dilation of the submucosal arteriovenous plexus, resulting in prolapse of upper anal and lower rectal tissue. 1

Pathophysiology of Hemorrhoids

Hemorrhoids are normal anatomical structures that become pathological when they enlarge and cause symptoms. They consist of:

• Connective tissue cushions surrounding arteriovenous communications between terminal branches of rectal arteries and veins 1
• Subepithelial smooth muscle that suspends and contributes to the bulk of hemorrhoidal cushions 1
• These cushions contribute 15-20% of resting anal pressure and ensure complete closure of the anal canal 1

Primary Risk Factors

The American Gastroenterological Association identifies several key factors that contribute to hemorrhoid development:

1. Inadequate fiber intake - leads to harder stools requiring more straining 1, 2
2. Prolonged sitting on the toilet - increases pressure on anal cushions 1, 3
3. Chronic straining during defecation - causes venous engorgement 1, 4
4. Constipation and diarrhea - both disrupt normal bowel habits 1, 2
5. Pregnancy - due to hormonal changes and increased intra-abdominal pressure 1
   • Approximately 80% of pregnant persons develop hemorrhoids, particularly in the third trimester 1
   • About 0.2% of pregnant women require urgent hemorrhoidectomy for incarcerated prolapsed hemorrhoids 1
6. Family history - suggests possible genetic predisposition 1
7. Increased intra-abdominal pressure - from various causes 4

Pathological Changes

When hemorrhoids become symptomatic, several changes occur:

• Abnormal swelling of anal cushions 1
• Stretching of the suspensory muscles 1
• Dilation of the submucosal arteriovenous plexus 1
• Dysregulation of vascular tone and vascular hyperplasia 5
• Destructive changes in supporting connective tissue within anal cushions 5

Age-Related Factors

• Peak prevalence occurs between 45-65 years of age 3
• Almost half of individuals older than 50 years experience symptomatic hemorrhoids 4
• The community-wide prevalence in the United States is approximately 4.4% 3

Important Clinical Considerations

• The pathogenesis of enlarged, prolapsing cushions is not fully understood, and rigorous proof for many proposed risk factors is lacking 1
• Symptoms attributed to hemorrhoids include bleeding, protrusion, itching, and pain 1
• External hemorrhoids are typically asymptomatic unless they become thrombosed 1
• Internal hemorrhoids can cause bright red bleeding due to arterial oxygen tension from arteriovenous communications 1
• Prolapse of rectal mucosa leads to mucus deposition on perianal skin, causing itchiness and discomfort 1

Preventive Measures

Based on the identified causes, prevention strategies include:

• Increasing dietary fiber intake to approximately 30g/day 1
• Ensuring adequate fluid intake, particularly water 1
• Avoiding prolonged sitting on the toilet 1, 3
• Addressing constipation through appropriate dietary and lifestyle modifications 1
• Using relaxation techniques and avoiding straining during bowel movements 1