Anal Haemorrhoids

Notes

Overview

Haemorrhoid Plexi are normal anatomical structures located within the anal canal. The term “Anal Haemorrhoids” usually refers to a pathology where the Haemorrhoidal Plexi are enlarged. They are mainly caused by chronic constipation and frequent defecation leading to dilation and engorgement of haemorrhoidal tissue. Common symptoms are bleeding, pain and itching. There are internal and external haemorrhoids.

Definition

Haemorrhoid plexus: venous drainage of the anal canal being at the haemorrhoid plexi. There is an internal and external haemorrhoid plexus. Dilatation of a haemorrhoid plexus causes haemorrhoids.
Anal haemorrhoids: collections of submucosal, fibrovascular, arteriovenous sinusoids that are part of normal anorectum; sometimes referred to as “varicose veins” of the anorectum.
Internal haemorrhoids: originate proximal to the dentate line and are covered by insensate transitional epithelium.
Prolapsed haemorrhoids: severe and painful form of internal haemorrhoids that push through the anus and hang out of the body.
External haemorrhoids: located distal to the dentate line and are covered by sensate anoderm or skin.

Haemorrhoids Overview

Anatomy

Anal cushions – normal vascular cushions at 3, 7 and 11 o’clock positions; composed of venous sinusoids, connective tissue and smooth muscle. Their function is to help with anal continence by contributing to mucosal sealing; haemorrhoids as pathology occur when these cushions enlarge, prolapse and become symptomatic.

Typically haemorrhoids occur in the same location as the main anal blood vessels pedicles (described as 3, 7 and 11 o’clock positions as seen in the supine position).

Anal canal – channel connecting the rectum to the anus, located within the anal triangle of the perineum, between the two ischioanal fossae

Anal Sphincters

Internal sphincter
- Involuntary control – continuation of circular fibers of the colon so it receives autonomic supply
- Surrounds upper 3/4 of anal canal
External sphincter
- Voluntary control
- Surrounds entire length of anal canal
- Consists of three parts – subcutaneous, superficial and deep

Intersphincteric plane

Between external sphincter muscle laterally and the longitudinal muscle (inner sphincteric muscle) medially
Contains anal glands
Can be opened up surgically to provide access for operations on the sphincter muscles

Anal glands

Apocrine glands
Occasionally infected and act as a source of anal fistula

Dentate (pectinate) line

Junction of the proximal and distal segments of the anal canal
Divides the anus into proximal 2/3 and distal 1/3
Situated at the middle of internal sphincter

Distinction	Above Dentate line	Below Dentate line
Embryology	Hindgut (endoderm)	Proctodeum (ectoderm)
Epithelium	Columnar	Stratified squamous
Arterial supply	Superior rectal a.	Middle rectal a.Inferior rectal a.
Venous drainage	Superior rectal v.	Middle rectal v.Inferior rectal v.
Innervation	Visceral – Inferior hypogastric plexus(insensitive to pain)	Somatic – Inferior rectal nerves: branches of Pudendal nerve(sensitive to pain)
Lymph drainage	Internal iliac	Superficial inguinal
Haemorrhoids	Internal	External

Hilton’s Line also called while line/anocutaneous line indicates lower end of the internal sphincter. Ischiorectal abscess when communicating with anal canal usually opens at or below Hilton’s line.

Aetiology and Risk factors

Chronic constipation (most common)
- Low fiber diet
- Dehydration
- Medication side effects
Chronic diarrhea
Increased intraabdominal pressure
- Pregnancy
- Ascites
- Obesity
Age (between 45 and 65)
Spending long periods of time on toilet (eg. reading)
Heavy lifting
Chronic cough

Portal hypertension increases the risk of developing rectal varices, which present similarly to haemorrhoids.

Pathophysiology

Haemorrhoids are a normal component of the anal canal – they become pathological when they cause symptoms

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Increased venous pressure/weakening of supporting structures

↓

Engorgement of haemorrhoidal plexus/displacement of anal cushion

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Venous dilation and stasis

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Inflammation and oedema

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Clinical manifestations (bleeding, prolapse, pain, itching)

Classification

External haemorrhoids – below the dentate line; can form thrombus and cause severe pain that usually resolves after 2 weeks.

Internal haemorrhoids – above dentate line; can prolapse out of anal canal.

Clinical manifestation

Bleeding: bright red blood (on toilet paper, pain or coating stool – not mixed with it)
Palpable mass: prolapsed internal or external haemorrhoids
Pain: external haemorrhoids (severe if thrombosed)
Anal pruritus: due to moisture associated with prolapsed internal haemorrhoid or difficulty to maintain hygiene ^2,4

Although external thrombosed haemorrhoids causes severe pain, the presence of severe pain raises the possibility of other conditions, including anal fissure, perirectal or perivaginal infection, abscess, and other inflammatory processes.

Commonest age of onset is young adulthood.

Approximately 40% of haemorrhoids are asymptomatic.

Examination

General inspection
- Visible haemorrhoids: either external or prolapsed internal
- Skin tags (resolved external hemorrhoids)
- Assess for thrombosis (tender, tense bluish lump)
- Prolapse on straining – ask patient to bear down
Digital rectal exam (DRE): palpable internal lumps; evidence of bleeding
Anoscopy – if history is suggestive of haemorrhoids but DRE inconclusive: bulging purplish-blue or dark pink masses, potentially tender

Differential diagnosis

Anal fissure
Anal fistula
Polyps
Rectal prolapse
Colorectal or anal cancer
Rectal varices (due to portal hypertension)
Proctitis
Solitary rectal ulcer syndrome

Diagnosis

Anoscopy – most conclusive and specific tests for haemorrhoids

Endoscopic evaluation with colonoscopy or flexible sigmoidoscopy; indicated if:

Patient is 40 years or older
High suspicion of haemorrhoids but unable to detect on anoscopy
Concerning clinical manifestations
Iron deficiency anemia
Risk factors for colonic disease

Labs – FBC (rarely performed): might show iron deficiency anaemia if significant bleeding (indicates endoscopic evaluation)

Treatment

General treatment (first-line)

Increase dietary fibre and fluid intake
Regular exercise
Avoid straining while passing stool
Avoid prolonged sitting on toilet

Medical treatment

Sitz baths
Stool softeners or bulk forming laxatives
Steroid cream – temporary relief of some symptoms
Pramoxine (anti-itching) – temporary relief of some symptoms

Surgical treatment

Rubber band ligation – Stage I, II and III
Infrared coagulation – Stage I and II
Sclerotherapy – Stage I and II
Stapled haemorrhoidopexy – Stage III
Haemorrhoidal artery ligation – Stage III
Surgical haemorrhoidectomy – Stage IV and mixed (combined external and internal haemorrhoids)

Avoid constipation/straining. Exercise, high-fiber diet and drinking plenty of water are good recommendations.

Complications and Prognosis

Complications

Anaemia
Pain
Heavy bleeding
Chronic unremitting prolapse of mucosal tissue
Strangulation
Ulceration
Thrombosis

Prognosis

External haemorrhoids are usually self-limiting and patients live with existing lumps
Rubber banding is a good treatment with good outcome

References

1. Community HealthPathways. Haemorrhoids: Hunter New England; [cited 2025 Sep 20]. Available from: https://hne.communityhealthpathways.org/13803.htm.

2. BMJ Best Practice. Haemorrhoids [updated 27 September 2024; [cited 2025 Sep 20]. Available from: https://bestpractice.bmj.com/topics/en-gb/181.

3. American Society of Colon & Rectal Surgeons. Hemorrhoids [cited 2025 Sep 20]. https://fascrs.org/patients/diseases-and-conditions/a-z/hemorrhoids

4. healthdirect. Haemorrhoids [cited 2025 Sep 20]. Available from: https://www.healthdirect.gov.au/haemorrhoids-piles.

5. GP Exams. Haemorrhoids [cited 2025 Sep 20]. Available from: https://gpexams.com/haemorrhoids/.

6. Bleday R, Breen E. Hemorrhoids: Clinical manifestations and diagnosis [updated 2025 Sep 11; cited 2025 Sep 20]. Available from: https://www-uptodate-com.ezproxy.newcastle.edu.au/contents/hemorrhoids-clinical-manifestations-and-diagnosis.