Anus & perianal area

Other nonneoplastic


Last author update: 1 May 2014
Last staff update: 16 September 2022

Copyright: 2002-2023,, Inc.

PubMed Search: Hemorrhoids [title] anus "loattrfree full text"[sb]

Elliot Weisenberg, M.D.
Page views in 2022: 20,192
Page views in 2023 to date: 1,699
Cite this page: Weisenberg E. Hemorrhoids. website. Accessed January 27th, 2023.
Definition / general
  • Dilated / ectatic varices of anal and perianal venous plexuses (anal cushions) normally present in submucosa
  • From Greek "haimorrhoides phlebes" - bleeding veins
  • Due to possibility of encountering other findings (see below), careful histopathologic evaluation of hemorrhoids is obligatory
  • Most literature estimates are 4 - 5% of general population, but many authors believe these numbers grossly underestimate its prevalence
  • Many sufferers do not seek medical attention
  • No sexual predominance (except younger, pregnant patients)
  • More common in whites vs. African Americans
  • Peak age of diagnosis 45 - 65 years, rare under age 30 except in pregnancy
  • Generally located at left lateral, right lateral and right posterior portions of the anal canal (4:00, 7:00, and 11:00 in lithotomy position)
  • Hemorrhoids proximal to dentate line are known as internal hemorrhoids; distal to dentate line, hemorrhoids are known as external hemorrhoids
  • Mixed hemorrhoids that cross the dentate line occur
  • Dilated venous plexuses arise from elevated pressure in the hemorrhoidal plexus
  • Hemorrhoidal cushions are likely normal structures involved in continence, normally dependency will lead to stasis
  • Elevated intraabdominal pressure leads to vascular dilation and if persistent, may lead to hemorrhoid formation
  • Degradation of normal supporting structures in the hemorrhoidal plexus also plays a role; older patients appear to be more prone to this
  • Direct arteriovenous communication with dilation occurs between terminal branches of rectal and hemorrhoidal arteries and veins of the hemorrhoidal plexuses
  • Increased intraabdominal pressure from pregnancy, rectal carcinoma, uterine leiomyomata, other pelvic masses, increased straining at stool often related to low fiber diet, prolonged sitting at stool, persistent diarrhea, ascites
  • There is controversy whether uncomplicated portal hypertension leads to hemorrhoids
  • Prolapsed hemorrhoids are prone to thrombosis and ulceration with accompanying inflammation
  • Thrombosed vessels undergo recanalization
Clinical features
  • Patients usually have painless bleeding, noticing blood in the toilet or on lavatory paper
  • Patients may experience pain or discomfort, especially with thrombosis, strangulation or ulceration
  • Anemia from hemorrhoids is unusual - patients should undergo hematologic evaluation
  • There is controversy concerning the mechanisms involved in serious hemorrhoidal bleeding in cirrhotics: excessive bleeding may be solely from coagulopathy or portal hypertension may be an important cause
  • Clinically four grades:
    • First degree, anal cushions that slide down past dentate line with straining at stool, that bleed with defecation
    • Second, anal cushions that prolapse with straining, but reduce spontaneously
    • Third, hemorrhoids that remain outside of the anal canal unless manually replaced
    • Fourth, hemorrhoids that cannot be reduced
  • Usually a clinical diagnosis; hypertrophied anal papillae may have similar appearance
Prognostic factors
  • Hemorrhoids are annoying, but significant morbidity is rare unless secondary to complications of therapy
  • Potential complications include pain, urinary retention, constipation, fistula, prolapse, incontinence
  • Medical intervention may include high fiber diet with stool softeners, topical analgesics, Sitz baths, bulk laxatives
  • Other interventions include rubber band ligation, sclerotherapy or cryotherapy, infrared coagulation or hemorrhoidectomy
Clinical images

Images hosted on other servers:

Prominent prolapsed true (internal) hemorrhoids

Hemorrhoids at anorectal junction (scroll down)

Microscopic (histologic) description
  • Dilated, thick walled, congested submucosal vessels and sinusoidal spaces, often with thrombosis; variable hemorrhage into connective tissue
  • Dilated spaces may show exuberant vascular proliferation confined to vessel known as papillary endothelial hyperplasia
  • Internal hemorrhoids are lined by rectal or transitional mucosa, external hemorrhoids have a squamous lining
  • Surface may show ulceration
  • Pale cells in epidermis resembling Paget cells (pagetoid dyskeratosis) in 68%, prominent in 22%, likely related to trauma related to prolapse (Arch Pathol Lab Med 2001;125:1058)
  • Examination of hemorrhoids may reveal low or high grade squamous intraepithelial lesions, invasive squamous cell carcinoma, rectal carcinoma, neuroendocrine tumors, melanoma, lymphoma, inflammatory bowel disease, nonspecific granulomas, Herpes Simplex Virus infection, syphilis
Microscopic (histologic) images

Contributed by Elliot Weisenberg, M.D.

Dilated, thick walled, congested submucosal vessels

Differential diagnosis
Back to top
Image 01 Image 02