Can constipation cause thrombosed hemorrhoids?

Can Constipation Cause Thrombosed Hemorrhoids?

While constipation is widely believed to contribute to thrombosed hemorrhoids, rigorous proof of this causal relationship is lacking, though clinical evidence suggests that straining and constipation often precede acute thrombosis. 1

The Evidence on Causation

What Guidelines Say About the Link

The American Gastroenterological Association emphasizes that rigorous proof for most commonly believed risk factors is lacking, including inadequate fiber intake, prolonged sitting on the toilet, and chronic straining at stool 1. Constipation has been proposed as a contributing factor, but none of these factors have been rigorously proven 1.

However, clinical observations paint a different picture:

• Acute thrombosed external hemorrhoids are often preceded by a bout of constipation, with blood stagnation and trauma to anal vessels from straining identified as the common denominator in thrombosis development 2
• Patients with hemorrhoids have a significantly higher prevalence of functional constipation compared to controls (OR 2.09; 95% CI 1.27-3.44) 3

The Pathophysiologic Mechanism

The relationship appears more complex than simple causation:

• Patients with hemorrhoids consistently demonstrate elevated anal resting pressures compared to controls, though whether this elevated pressure causes or results from enlarged hemorrhoids remains unclear 1
• Anal pressures normalize after hemorrhoidectomy, suggesting the hemorrhoids themselves may contribute to the pressure abnormality 1
• Severely constipated women without hemorrhoids have normal anal pressure profiles, while patients with hemorrhoids have abnormally high anal pressures regardless of constipation status 4

This suggests that hemorrhoids are associated with anal hypertonia rather than constipation per se 4.

Clinical Presentation of Thrombosed Hemorrhoids

External Thrombosis (Most Common)

• Patients present with acute-onset anal pain and a palpable perianal lump 5
• Thrombosed external hemorrhoids occasionally bleed when local pressure causes erosion through overlying skin 5
• Mean age of presentation is 36 years, with male predominance (2:1 ratio) 2
• Left-sided predominance (51%), unlike internal hemorrhoids which favor the right side 2

Internal Thrombosis (Far Less Common)

• Typical symptoms include pain, pressure, bleeding, mucus production, and inability to reduce spontaneously prolapsing tissue 5
• Represents fourth-degree hemorrhoids when acutely thrombosed and incarcerated 5

Management Algorithm

For Thrombosed External Hemorrhoids

Timing is critical for treatment decisions:

• If presenting within 72 hours of symptom onset: surgical excision under local anesthesia provides faster symptom resolution and lower recurrence rates 6, 7
• If presenting beyond 72 hours: conservative management is preferred with stool softeners, oral and topical analgesics (such as 5% lidocaine) 6, 7
• Incision and drainage of the thrombus alone is not recommended 6

For Thrombosed Internal Hemorrhoids (Incarcerated, Prolapsed)

• Hemorrhoidectomy or excision of external component with rubber band ligation of internal hemorrhoids is recommended 6
• In pregnancy, approximately 0.2% require urgent hemorrhoidectomy for incarcerated prolapsed hemorrhoids 6

Prevention Strategy

Despite lack of rigorous proof, the universal recommendation is to add dietary fiber and avoid straining at stool 5:

• Increase dietary fiber to approximately 30 g/day 6
• Psyllium reduces hemorrhoidal bleeding and painful defecation in controlled trials 5
• Adequate fluid intake to soften stools 6
• Osmotic laxatives (polyethylene glycol or lactulose) are safe options 6
• Avoid stimulant laxatives due to conflicting safety data 6

Critical Pitfalls to Avoid

• Never assume anal pain is from uncomplicated hemorrhoids alone—anal pain generally is not associated with hemorrhoids unless thrombosis has occurred, so new-onset anal pain suggests other pathology 5
• Up to 20% of patients with hemorrhoids have concomitant anal fissures, which also cause severe pain 5, 8
• Small intersphincteric abscesses can present as new-onset anal pain without visible source 5
• Do not attribute all rectal bleeding to hemorrhoids without proper evaluation—patients at risk for colorectal cancer require colonoscopy 9