What is the pathology and management of hemorrhoids in adults, particularly those over 50, with potential complications and comorbidities such as increased pressure during bowel movements, pregnancy, obesity, and low-fiber diet?

Pathology of Hemorrhoids

Hemorrhoids represent the pathologic enlargement and distal displacement of normal anal cushions—vascular structures in the subepithelial space of the anal canal consisting of connective tissue surrounding direct arteriovenous communications between terminal branches of the superior rectal arteries and rectal veins. 1

Normal Anatomy and Physiologic Function

• Anal cushions are normal structural components present from infancy, located in the subepithelial space of the anal canal 1
• These cushions consist of connective tissue surrounding arteriovenous communications between terminal branches of the superior rectal arteries and the superior, inferior, and middle rectal veins 1
• Subepithelial smooth muscle arising from the conjoined longitudinal muscle layer passes through the internal anal sphincter and inserts into the subepithelial vascular space, suspending and contributing to the bulk of hemorrhoidal cushions 1
• Normal anal cushions contribute approximately 15-20% of resting anal pressure 1, 2
• They serve as a conformable plug to ensure complete closure of the anal canal and maintain continence 1, 2
• Most people have 3 cushions, though the typical right anterior, right posterior, and left lateral configuration occurs only 19% of the time in cadaver studies 1

Pathophysiology of Symptomatic Hemorrhoids

The core pathologic process involves abnormal swelling of the anal cushions, stretching of the suspensory muscles, and dilation of the submucosal arteriovenous plexus, resulting in prolapse of upper anal and lower rectal tissue through the anal canal. 1

Vascular Changes

• Abnormal dilatation and distortion of the vascular channel occurs within the anal cushion 3
• Dysregulation of vascular tone and vascular hyperplasia appear to play important roles in hemorrhoidal development 3
• The arteriovenous communications within anal cushions explain why hemorrhoidal bleeding is typically bright red due to arterial oxygen tension 1, 4

Structural Deterioration

• Destructive changes occur in the supporting connective tissue within the anal cushion 3
• Stretching of the suspensory smooth muscle leads to loss of structural support 1
• This structural failure allows distal displacement and prolapse of the hemorrhoidal tissue 4

Symptomatic Manifestations

• Prolapsed tissue is easily traumatized during bowel movements, leading to bleeding 1
• Prolapse of rectal mucosa leads to mucus deposition on perianal skin, causing itching and discomfort 1
• External hemorrhoids remain asymptomatic unless they become thrombosed, presenting as an acutely painful perianal lump 1, 5
• Persisting skin tags after thrombosis resolution can lead to hygiene problems and secondary irritation 1

Classification Systems

Internal vs. External Hemorrhoids

• Internal hemorrhoids originate above the dentate line and cause rectal bleeding, discomfort, and tissue prolapse 4
• External hemorrhoids arise below the dentate line and cause rectal pain when engorged or thrombosed 4
• Mixed hemorrhoidal disease involves concurrent internal and external components 4

Grading of Internal Hemorrhoids

• Grade I: Prolapse into the anal canal only 4, 6
• Grade II: Prolapse beyond the anus with spontaneous reduction 4, 6
• Grade III: Prolapse requiring manual reduction 7, 4, 6
• Grade IV: Irreducible prolapse, often incarcerated and thrombosed 7, 4, 6

Risk Factors and Etiology

Commonly Cited but Unproven Factors

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, 5

• Constipation, diarrhea, pregnancy, and family history have been proposed but none rigorously proven 1
• Despite lack of rigorous proof, the universal recommendation remains to add dietary fiber and avoid straining 5

Pregnancy-Related Pathology

• Hemorrhoids occur in approximately 80% of pregnant persons, more commonly during the third trimester 7
• Compression of the rectum by the gravid uterus contributes to hemorrhoid development 7
• Approximately 0.2% of pregnant women require urgent hemorrhoidectomy for incarcerated prolapsed hemorrhoids 1, 7

Thrombosed Hemorrhoids: Specific Pathology

• Thrombosis in external hemorrhoids results in painful swelling and acute-onset anal pain with a palpable perianal lump 1, 5
• Thrombosed external hemorrhoids occasionally bleed when local pressure causes erosion through overlying skin 5
• Internal thrombosis presents with pain, pressure, bleeding, mucus production, and inability to reduce spontaneously prolapsing tissue 5

Critical Clinical Pitfalls

Never assume all anorectal symptoms are due to hemorrhoids—this attribution error leads to overlooking other pathology. 7, 2

• Up to 20% of patients with hemorrhoids have concomitant anal fissures 7, 5
• Anal pain generally is not associated with uncomplicated hemorrhoids unless thrombosis has occurred, so new-onset anal pain suggests other pathology 5
• Hemorrhoids themselves do not directly cause fecal incontinence; prolapsing hemorrhoids contribute to minor incontinence through mechanical obstruction and soilage rather than true sphincter dysfunction 2
• Anal itching from prolapsing hemorrhoids is just as likely due to inadequate hygiene or minor incontinence as it is to the hemorrhoids themselves 2
• A careful anorectal evaluation is warranted for any patient reporting both hemorrhoids and incontinence symptoms 2