Where are hemorrhoids typically found in the body?

Anatomical Location of Hemorrhoids

Hemorrhoids are found in the subepithelial space of the anal canal, consisting of connective tissue cushions surrounding direct arteriovenous communications between terminal branches of the superior rectal arteries and the superior, inferior, and middle rectal veins. 1

Anatomical Structure and Classification

• Hemorrhoids are classified as internal or external according to their position relative to the dentate line, which serves as the boundary between the upper and lower anal canal 1, 2
• Internal hemorrhoids originate above the dentate line and are covered by columnar epithelium 2
• External hemorrhoids arise below the dentate line and are covered by anoderm, which is highly innervated by somatic pain receptors 3
• Mixed hemorrhoids involve concurrent internal and external hemorrhoidal disease 2

Normal Anatomical Distribution

• Most people have 3 hemorrhoidal cushions in the anal canal 1
• The traditional description suggests they are located in right anterior, right posterior, and left lateral positions 1
• However, cadaver studies have shown this "typical" configuration occurs in only 19% of individuals 1
• These normal anal cushions contribute approximately 15-20% of the resting anal pressure and serve as a conformable plug to ensure complete closure of the anal canal 1

Pathophysiology of Symptomatic Hemorrhoids

• Symptomatic hemorrhoids develop when there is abnormal swelling of the anal cushions, stretching of suspensory muscles, and dilation of the submucosal arteriovenous plexus 1
• This results in prolapse of upper anal and lower rectal tissue through the anal canal 1
• Multiple studies have shown elevated anal resting pressure in patients with hemorrhoids compared to controls 1
• The pathogenesis of enlarged, prolapsing cushions is not fully understood, though factors such as inadequate fiber intake, prolonged sitting on the toilet, chronic straining, constipation, diarrhea, pregnancy, and family history have been proposed 1

Clinical Significance of Location

• Internal hemorrhoids typically cause painless rectal bleeding during defecation, with or without tissue prolapse 4
• External hemorrhoids are usually asymptomatic unless they become thrombosed, at which point they present as an acutely painful perianal lump 1
• The grading system for internal hemorrhoids (I-IV) is based on the degree of prolapse, which affects treatment options 1, 2
• When evaluating hemorrhoidal bleeding, it's important to note that hemorrhoids typically cause bright red blood rather than occult bleeding 5
• A positive fecal occult blood test in a patient with hemorrhoids should not be attributed to the hemorrhoids without further investigation 5

Common Pitfalls in Diagnosis

• Many patients and physicians incorrectly attribute any anorectal symptom to hemorrhoids 1
• Anal pain is generally not associated with uncomplicated hemorrhoids unless thrombosis has occurred, suggesting other pathology when present 1
• Up to 20% of patients with hemorrhoids have concomitant anal fissures 1
• Anemia due to hemorrhoidal disease is rare (0.5 patients/100,000 population) 5
• Complete colonic evaluation is mandatory when bleeding is atypical for hemorrhoids or when a positive Hemoccult test is present 5