Pathophysiology of Hemorrhoids

Varut Lohsiriwat MD. PhD. Associate Professor of Surgery

Faculty of Medicine Siriraj Hospital, Mahidol University

Bangkok, Thailand

Outline

• Applied anatomy of hemorrhoids

• Pathophysiology of hemorrhoids

• Symptoms & clinical evaluation

Applied Anatomy of Hemorrhoids

Blood Supply to Anorectal Region

Lohsiriwat V. Common anorectal diseases, 1st Ed. Siriraj Publisher, Bangkok 2015

Superior rectal (hemorrhoidal) artery

Inferior rectal (hemorrhoidal) artery

Middle rectal artery

From internal iliac artery

From internal pudendal artery

To internal iliac vein

To internal pudendal vein

Anal Cushions & Hemorrhoids

Lohsiriwat V. World J Gastroenterol 2012

Types of hemorrhoids

Internal hemorrhoids Located above the dentate line Covered by mucosa

External hemorrhoids Located distal to the dentate line Covered by skin

Lohsiriwat V.

cc

Fragmented subepithelial

smooth muscle (Trietz’s muscle or mucosal suspensory ligament)

Markedly dilated vascular channels 5 mm

Lohsiriwat V. World J Gastroenterol 2012

Histology of Hemorrhoids

Pathohysiology of Hemorrhoids

Theory of Hemorrhoid Formation

1. Sliding anal cushions/ Loss of fixation

Presenting symptom: Prolapse

2. Rectal redundancy/ Internal rectal prolapse

Presenting symptom: Circumferential prolapse

3. Vascular abnormalities

Presenting symptom: Bleeding

Lohsiriwat V. World J Gastroenterol 2012

(1) Theory of ‘Sliding Anal Cushions’

Destructive changes in the supporting connective tissue of anal cushion

Distal displacement of anal cushion

+

Abnormal vascular dilatation

(2) Theory of ‘Rectal Redundancy’

• Some clinicians postulated a redundant rectal mucosa as a primary alteration of hemorrhoids.

• This theory proposes that prolapsed hemorrhoids is always associated with an internal rectal prolapse.

(3) Theory of ‘Vascular Abnormalities’

3.1 Increased anorectal blood flow

3.2 Vascular hyperplasia

3.3 Dysregulation of the vascular tone

(i.e. ↑ vasodilator)

3.4 Inflammatory reaction involving the

vascular wall and surrounding tissue

Chung et al. Eur J Clin Invest 2004

Han et al. Chinese J Gastrointest Surg 2005

Aigner et al. J Gastrointest Surg 2006

Lohsiriwat et al. Current Vascular

Pharmacology 2018 (next slide)

Risk Factors for Hemorrhoids Strong risk factors (OR >2)

Constipation

Diarrhea

Modest risk factors (OR 1.1-2.0)

A history of childbirth

Depression

Low fiber intake

Obesity

Non-sedentary behavior

Pregnancy

ANAL CUSHIONS

Mechanical injury

Aging

(degenerative change)

Straining Increased anorectal blood flow

Venous stasis

Tissue inflammation

HEMORRHOIDS

Loss of fixation Disruption of supporting tissue in anal cushions

Abnormal venodilation Engorged and tortuous veins

in hemorrhoidal plexus

Pathophysiology & Risk Factors

Symptoms & Clinical Evaluation

Presenting Symptoms

• Bleeding

– Bright-red blood (due to direct arteriovenous communication in the anal cushion)

– Blood seen on the surface of stool, or dripping in the bowl, or on tissue paper during anal cleansing (if blood is mixed in stool, it suggests bleeding from GI tract elsewhere)

• Prolapse (depending on grade of hemorrhoids)

• Pain (if thrombosed or strangulated)

Clinical Evaluation

• Inspection

• Digital rectal examination

– In general, internal hemorrhoids should be palpable unless they are large or thrombosed

– Differential diagnosis of palpable intra-anal canal lesion includes anal malignancy and neoplasms

• Proctoscopy

– Number of lesion, location, grading, and any bleeding stigmata should be noted

Goligher’s Classification of Internal Hemorrhoids

1st degree (Grade I): no prolapse

2nd degree (Grade II): prolapse through the anus on straining but reduce spontaneously

3rd degree (Grade III): prolapse through the anus on straining and require manual reduction

4th degree (Grade IV): prolapse stays out at all times and is irreducible

Hemorrhoidectomy

Non-excisional Operation

Sclerotherapy

Dietary and Lifestyle Modification

Rubber Band Ligation

Medication - Venotonics

Grade 1 Grade 2 Grade 3 Grade 4

Modification from Lohsiriwat V. Approach to Hemorrhoids. Curr Gastroenterol Rep 2013;15:332-6

Approaches to Hemorrhoids (Based on Goligher’s Classification)

Approaches to Hemorrhoids (Based on Pathophysiology)

Sliding anal cushions (CC: Prolapse)

Rx: banding, sclerotherapy, plication, hemorrhoidectomy

Rectal redundancy (CC: Circumferential Prolapse)

Rx: stapled hemorrhoidopexy

Vascular abnormality (CC: Bleeding)

Rx: phlebotonic (venotonic), vasoconstrictor, anti-inflammatory, hemorrhoid artery ligation

Lohsiriwat V. World J Gastroenterol 2012

CONCLUSIONS

• Exact pathophysiology of hemorrhoids

Unknown (likely to be multi-factorial)

- Sliding anal cushions/ Loss of fixation

- Rectal redundancy/ Internal rectal prolapse

- Vascular abnormalities

• Different philosophy Different approach