Haemorrhoids

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Clinically Relevant Anatomy

Anal canal is the end part of the gastrointestinal tract (GIT), it is about 4cm in length in women and more longer in men to be about 4.4 cm in length, passes downwards and backwards forming the anorectal angle. The internal lining mucousa membrane of anal canal divided by the pectinate line into two portions: the upper one the vertical anal columns (8-10 anal fold), at there ends there are valves (anal valves), above each one of these anal valves there is a shallow mucosal pocket called the anal sinus. the lower part below the line is formed of nonkeratinized squamous epithelium with no ducts it is sensitive to pain and provides an internal moisturizing to the canal. The upper anal canal lined by three main anal cushions they are very vascular, their positions contribute with the anatomy of anal canal to help with continence, the first one located in the right anterior at 11 o'clock, the second at right posterior at 7 o'clock and the last one on the left lateral aspect at 3 o'clock of the anal canal, they consist of connective tissues and connection of arteries and veins, supported by smooth muscles and connective tissues and supplied by the rectal artery. In addition to the three main cushions there are many minor cushions between them.

The anal canal is described into anatomical and surgical anal canal. The anatomical anal canal starts from the dentate line and ending at the anal verge, while the surgical anal canal extends from the anorectal ring (junction between the anal canal and rectum) to the anal verge.

Mechanism of Injury / Pathological Process

Hemorrhoids is defined as a swollen/ enlargement/ or displacement of vascular anal cushions, it may be symptomatic condition or a symptomatic condition in others that affecting millions of people. The exact pathophysiology is still unclear but there are many theories.

Sliding of lining anal cushions theory, that was described in 1975, it suggested that the hemorrhoids happens when there is break down and downward displacement  of structures of internal anal cushions when the supporting structures of anal cushions become week this will this will predispose to prolapse of anal cushions such as during defecation or an increase of intra-abdominal pressure, theses displacement changes are associated with inflammatory process of internal canal, venous dilatation, process of degeneration of the fibroelastic and collagen tissues, vascular thrombosis and/ or anal sub-epithelial muscle this theory still accepted.

Hemodynamic and hypervascularization theory, the anal cushions are supplying by  terminal branches of the superior rectal artery, they are larger in diameter that is associated with an increase in the blood flow and venous back flow because of collapsed anastomosis of arteriovenous that lead enlargement and prolapse of cushions.

The smooth muscles around arteriovenous plexus act as a sphincter to reduce the arterial  inflow of the blood and improve venous drainage and so decrease the enlargement of arteriovenous plexus and the risk of hemorrhoids is another possible explanation for pathophysiology of hemorrhoids.

In a large sample of hemorroidal tissues there was an increase in microvascular density that support the phenomena of neovascularization specially when there is a thrombosis. Several enzymes and mediators play a role in the development of hemorrhoids such as; angiogenesis-related protein such as VEGF, matrix metalloproteinase (MMP), and zinc-dependent proteinase that have a degradation and remodeling effect.

Types of Hemorrhoids

Hemorrhoids is classified according to the location to pectinate line into:

Internal hemorrhoids originates from dilatation of the venous plexus above the dentate line and classified into four grades according to Goligher’s classification:

• Grade I, visible hemorrhoids with no prolapse.
• Grade II, prolapse of anal cushions through the anus at straining or increase of intra-abdominal pressure but they reduce spontaneously.
• Grade III, prolapse of anal cushions through the anus at straining or increase of intra-abdominal pressure but need manual reduction.
• Grade IV, that is nonreducible prolapse.

External hemorrhoids originates from dilatation of the venous plexus below the dentate line

Risk / Predisposing Factors

• Activities that increase intra abdominal pressure like weight lifting, straining.
• Chronic constipation
• Pregnancy (constipation or decrease support of connective tissues due to elasticity during pregnancy)
• Prolonged toileting in sitting position that lead disruption of blood back flow
• Bad dietary habits
• Hard feces (an increase in consistency of stool that make it difficult to pass) or diarrhea.

Clinical Presentation

In patients how suffer from hemorrhoids approximately 4 out of 10 will have symptoms . Clinical presentation of the patient depends on the degree and type of hemorrhoid, external hemorrhoid may be come with acute pain if there is thrombosis, feeling of swelling / lump around anus, bleeding that is usually painless, bright red bleeding related to internal hemorrhoids and associated with bowel movement.

Diagnostic Procedures

Detailed patient history and physical examination is important to diagnose hemorrhoids ad exclude any possible causes.

With external examination to detect if there is any anal discharge, lumps out the anus, thrombosis associated with external hemorrhoids that feels like firm, purplish nodule and tender with palpation, fecal soiling, or anal fissure. Digital/ Internal examination examination we can not detect internal hemorrhoids but we can detect if there is an abnormal internal mass, scar, fistula, or anal stenosis.

Anoscopy procedure is important to be carried if there is bleeding or the digital exam revealed that there is an internal mass and to confirm internal hemorrhoids, it can detect the size, location, and the severity of inflammation. In patients above 50 years old total colonoscopy can be done if there is bleeding for exclusion of causes.

Management / Interventions

Conservative management

• Diet and Life style modification

Increase fluid and fiber intake will help to improve constipation and movement of stool, as well as, practicing regular exercise and physical activity will help to improve bowel movement, change bowel habit and decreasing sitting time of defecation.

• Topical analgesic, anti-inflammatory, corticosteroid treatment or laxatives.
  

Non- surgical intervention

• Electrotherapy

Known as electrocoagulation in the outpatient setting using an anoscope a probe carrying a direct electric current with intensity between 8 mA and 16 mA will be directed to the base of hemorrhoid, the time of the session depends on the grade, it is used as an alternative procedure for grade I or II and can be used for grade III or IV as an alternative to surgery.

• Sclerotherapy

It uses chemicals such as zinc chloride, quinine, and polidocanol to be injected into hemorrhoidal tissues this is used to decrease the vascularity, and redundant tissue, and gradually the hemorrhoid will shrink and obliterates over time, used in grade I and II internal hemorrhoids  with no need to anaesthetia during the procedure.

• Rubber band ligation

Using an anoscope the hemorrhoid will be tied at its base by a rubber band to cut the blood supply, within 3 to 7 days later. This prolapsed part of hemorrhoid will fall off.

Differential Diagnosis

• Anal fissure, tear or opening of the moist thin tissues lining the anal canal that may cause bleeding and pain it is usually caused by stretching of anal canal because of hard bowel movement, trauma to the lining tissues,
• Fistula
• Colorectal cancer is important to be excluded if there is bleeding.

Resources

American Gastroenterological Association medical position statement: Diagnosis and treatment of hemorrhoids

Electrotherapy for the treatment of hemorrhoids NICE guidelines.