Anorectal disease Flashcards
What is the anatomy of the anus? Positioning from lithotomy position (looking from the anus and up)?
The anus is lined by discontinuous masses of spongy vascular tissue – the anal cushions, which contribute to anal closure. From the lithotomy position, the three anal cushions are at 3, 7 and 11 o’clock (where arterial plexuses also enter the anal canal). They are attached by smooth muscle and elastic tissue.
How does the cellular anatomy of the anal canal change at the dentate line?
Aka pectinate line/squamomucosal junction. Upper region is lined by simple columnar epithelium. Below the line, lining is stratified squamous epithelium.
What is the vasculature of the anal cushions?
Superior rectal artery (from the IMA; above the dentate line) and inferior rectal artery (from the internal pudendal artery; below the dentate line).
What are haemorrhoids?
Disrupted and dilated anal cushions.
What is the epidemiology of haemorrhoids: Prevalence? Age? Ethnicity? Socioeconomic class?
Very common – estimated 50% prevalence. Peak 45-60y/o. More common in Caucasians and higher socioeconomic class.
What is the aetiology/risk factors of haemorrhoids? (x7)
Gravity, increased anal tone, straining at stool (making them protrude to form piles), congestion from a pelvic tumour, pregnancy, congestive heart failure, portal hypertension.
What is the pathogenesis of haemorrhoids?
Vascular cushion protrudes through tight anus, become more congested, and hypertrophy to protrude again more readily. This continues in a vicious cycle and the protrusions may then strangulate.
What is the classification of haemorrhoids?
o FIRST DEGREE: remain in the rectum
o SECOND DEGREE: prolapse through the anus on defecation but spontaneously reduce
o THRID DEGREE: as for second degree but require digital reduction
o FOURTH DEGREE: remain persistently prolapsed.
What is an internal, external and mixed haemorrhoid?
External originate below the dentate line and therefore associated with the external rectal plexus; internal originate above the dentate line, so the internal rectal plexus is implicated; mixed originate above and below the dentate line, so both rectal plexi are implicated.
What are the symptoms of haemorrhoids? (x4)
o PR bleeding: from trauma or from the capillaries of the underlying lamina propria; bright red, often coating stools, on the tissue or dripping into the pan after defecation.
o Mucous discharge
o Pruritus ani
o Pain in external haemorrhoids, but NOT tenesmus (CRAMPING rectal pain)
What are the signs of haemorrhoids? (x2)
o Signs of anaemia
o Palpable mass; often can be visualised if external or protruding internal.
Why are some haemorrhoids painless? Exception?
Those that arise ABOVE the dentate line (internal haemorrhoids) are not innervated by sensory fibres, so are painless UNLESS they thrombose. Thrombosis can occur when they protrude and are gripped by the anal sphincter, blocking venous return.
What are the differentials for someone with symptoms of haemorrhoids? (x5)
Perianal haematoma, anal fissure, abscess, tumour, proctalgia fugax (muscle spasm around anus resulting in pain).
What are the complications of haemorrhoids? (x2)
They are vulnerable to trauma e.g. from hard stools. Most complications arise from their management.
What is lamina propria?
Connective tissue that lines mucosa.
What are the investigations for haemorrhoids? (x3)
o PR exam
o Proctoscopy/sigmoidoscopy to visualise internal haemorrhoids
o Colonoscopy/flexible sigmoidoscopy to exclude proximal pathology if over 50 years old.
What are the disadvantages of PR exam?
Internal haemorrhoids are not palpable.
What are the indications for medical management of haemorrhoids?
First degree haemorrhoids.
How are haemorrhoids medically managed? (x5)
Increased fluid and fibre are key +/- topical analgesics, and stool softener (bulk forming). Topical steroids for short periods to reduce inflammation and irritation (only used for short period as can cause thinning of mucosa which increases bleeding risk.
What are the indications for non-operative management of haemorrhoids?
Second and third degree, or first degree non managed medically.
How are haemorrhoids non-operatively managed? (x4)
o RUBBER BAND LIGATION: banding produces an ulcer and haemorrhoid falls off. Can only be used on internal haemorrhoids, at least 1 cm above dentate line.
o SCLEOSANTS: 2ml of 5% phenol in oil is injected into the haemorrhoid above the dentate line; vein walls collapse inducing fibrotic reaction.
o INFRARED COAGULATION: method of cauterisation; applied to localised areas of haemorrhoids, coagulates vessels and tethers mucosa to subcutaneous tissue.
o BIPOLAR DIATHERMY AND DIRECT CURRENT ELECTROTHERAPY: cauterisation that causes coagulation and fibrosis after local application of heat.
What are the side effects of rubber band ligation? (x3)
Bleeding, infection, pain.
What are the side effects of sclerosants? (x2)
Impotence and prostatitis – when agent injected into prostate which is nearby.
What is the advantage of infra-red coagulation to rubber band ligation?
Less painful.
What are the indications for surgical management of haemorrhoids?
If all other management options fail; fourth degree haemorrhoids.
How are haemorrhoids managed surgically? (x2)
o EXCISIONAL HAEMORRHOIDECTOMY: excision of haemorrhoids and ligation of vascular pedicles (tying off branches of an artery whose main function is not supplying the anus).
o STAPLES HAEMORRHOIDOPEXY: procedure for prolapsing haemorrhoids when there is a large internal component. Remove most of the haemorrhoidal tissue and repositioning the remaining tissue back to its original position.
What are the complications of haemorrhoidectomy? (x4)
Constipation, infection, stricture, bleeding.
How are prolapsed and thrombosed haemorrhoids managed?
Analgesia, ice and stool softeners. Pain usually resolves in 2-3 weeks.
What is the prognosis of haemorrhoids?
Most resolve without health intervention.
What is rectal prolapse?
The mucosa or all layers of the rectum may protrude through the anus.
What is defined as the mucosa of the rectum?
Epithelium, connective tissue and thin muscle layer. It is separated from the muscularis and serosa by the submucosa.
What is the aetiology/risk factors of rectal prolapse? (x7)
o Lax sphincter
o Increased abdominal pressure from prolonged straining (constipation), pregnancy and benign prostatic hyperplasia.
o Pelvic floor dysfunction
o Chronic neurological disorder from previous trauma, lumbar disc disease, cauda-equina syndrome, MS, spinal tumours.
o Parasitic infections such as schistosomiasis
o Psychological disorders
o Cystic fibrosis
What is the classification of rectal prolapse? (x3)
o Type 1, partial (mucosal layer only), or Type 2, complete (all layers of the rectal wall prolapse) – see photo, B and A respectively.
o External if they protrude from the anus and are visible externally, or internal if they do not
o Circumferential where the whole circumference of the rectal wall prolapses, or segmental if only parts of the rectal wall circumference prolapse.
What are the investigations for rectal prolapse? (x4)
o Proctoscopy/sigmoidoscopy/colonoscopy: may reveal oedema of the distal rectal mucosa and rectal ulceration. Also used to simultaneously screen for cancer.
o Video-defecography: x-ray test used to diagnose internal intussusception (see photo)
o Anorectal manometry: determines status of sphincters to assess cause of prolapse
o Anal electromyography: to assess neuronal function and evaluate incontinence
How are perineal abscesses classified? (x4)
According to their anatomical location: perianal (beneath skin of anal canal), ischiorectal (from the external anal sphincter to the ischiorectal space), intersphincteric (between internal and external anal sphincters) and supralevator abscess.
How are anorectal fistulae managed? (x9) When is each procedure used?
o FISTULOTOMY: cut the fistula open along its whole length so it heals as a flat scar. It is then packed on a daily basis to help heal.
o SETON STITCH: done when the fistula passes through a significant portion of the anal sphincter muscle. A loose seton is when a piece of surgical thread is left in the fistula for several weeks to keep it open. This allows drainage and helps to heal. This does not cure fistulae.
o CUTTING SETON: seton inserted and tightly to help cut through the fistula more slowly than fistulotomy. On each tightening, the seton cut through the sphincter muscle and heals as it goes.
o ADVANCEMENT FLAP PROCEDURE: when fistulotomy is contraindicated because of incontinence. Cutting or scraping out the fistula and covering the hole where it entered the rectum with a flap of tissue taken from the rectum.
o LIFT (ligation of the intersphincteric fistula tract) PROCEDURE: When fistula passes through the sphincter muscles. A cut is made in the skin above the fistula and the sphincter muscles are moved apart. The fistula is sealed at both ends and cut open so it lies flat (see photo).
o ENDOSCOPIC ABLATION: endoscopic tube placed in fistula and electrode passed through the endoscope and used to seal its opening.
o LASER SURGERY: used to seal the fistula.
o FIBRIN GLUE: the only non-surgical option. Injecting a glue into the fistula under GA which helps seal the fistula and encourage it to heal.
o BIOPROSTHETIC PLUG: insertion of cone-shaped plug made from animal tissue to block the internal opening.
What are the types of anorectal fistulae?
o EXTRASPHINCTERIC: rectum/sigmoid, through the levator ani and open onto the skin.
o SUPRASPHINCTERIC: between the internal and external sphincter muscles, extend above the puborectalis muscles, descend between this muscle and the levator ani, opening onto the skin.
o TRANSPHINCTERIC: between the internal and external sphincter muscles, crossing the external sphincter muscle and opening onto the skin.
o INTERSPHINCTERIC: between the internal and external sphincter muscles, pass through the internal sphincter muscle and open very close to the anus.
o SUBMUCOSAL: pass superficially beneath the submucosa and do not scross either sphincter muscle.
