Anal Pathology Flashcards
Anal canal - histology
- rectum until the pectinate (dentate) line at junctional zone of epithelium –> cuboidal epithelium
- after pectinate line (anal canal) –> non-keratinised stratified squamous epithelium
- after external anal sphincter (anal skin) –> keratinised stratified squamous epithelium
Anus - Innervation
Internal Anal Sphincter
- involuntary (smooth muscle)
- contraction = sympathetic fibers from superior rectal and hypogastric plexuses
- inhibition of contraction = parasympathetic (pelvic splanchnic S2-S4)
External Anal Sphincter
- voluntary (skeletal muscle)
- contraction = Branch from S4 and from the inferior hemorrhoidal branch of the pudendal nerve (S2,3,4)
Defecation Reflexes
- faeces in rectum –> distension of rectal wall
- activation of stretch receptors
- afferent sensory fibres to spinal cord (S2-S4)
- Activation of myenteric plexus (Auerbach) –> smooth muscle –> peristalsis (intrinsic reflex)
- efferent pelvic splanchnic (parasympathetic reflex)
- relaxation of internal anal sphincter
- stool moves down the rectum
- voluntary inhibition of external anal sphincter
Haemorrhoids - definition
- Haemorrhoids are normal vascular-rich cushions made of sinusoids, connective tissue, and smooth muscle located within the anal canal, usually occupying the left lateral and right anterior and posterior positions.
- They become pathological as they enlarge and cause symptoms, termed haemorrhoidal disease.
Haemorrhoids - aetiology
- excessive straining due to either chronic constipation or diarrhoea
- increase in intra-abdominal pressure can be caused by pregnancy or ascites or obesity
therefore risk factors are:
- age between 45 and 65
- constipation
- pregnancy
- pelvic space occupying lesion eg large ovarian cyst
Internal haemorrhoids
- originate proximal to the dentate line and covered by insensate transitional epithelium
- not as painful due to autonomic innervation
- grade 1 = limited to anal canal
- grade 2 = beyond anal canal but reduces spontaneously on cessation of straining
- grade 3 = outside anal canal and manually reducible
- grade 4 = outside anal canal and irreducible
External haemorrhoids
- located in the distal anal canal, distal to the dentate line, and covered by sensate anoderm or skin
- more painful due to somatic innervation
Haemorrhoids - clinical features
- rectal bleeding = bright red bleeding in association with defecation or straining
commonly painless bleeding - Importantly, blood is seen on the surface of the stool, not mixed in.
- perianal discomfort: can have itching or feeling of incomplete evacuation
- moist, pink bumps in anus (or purple or blue)
- constant pain = thrombosed external haemorrhoids
Haemorrhoids - investigations
- Dx is clinical (rectal examination) or
- anoscopic examination (hollow tube device with a light attached at one end)
- FBC (may have microcytic anaemia)
consider colonoscopy/flexible sigmoidoscopy if you suspect serious pathology like IBD or cancer
Haemorrhoids - management
1st line - dietary and lifestyle modification = increased fibre intake and adequate fluids, consider fibre supplements and analgesia
- topical hydrocortisone rectal, topical local anaesthetic (lignocaine gel
- 2nd line = rubber band ligation (elastic bands around it and falls off) or sclerotherapy (injection of sclerosing agent - makes it shrink)
- 3rd line = surgical haemorrhoidectomy
(if large symptomatic, unresponsive to other tx or thrombosed)
Anal fissure - definition
Anal fissure is a split in the skin of the distal anal canal characterised by pain on defecation and rectal bleeding. It is a common condition in young to middle-aged adults.
Anal fissure - aetiology
- passage of a hard stool bolus may precipitate (tears the anal skin from the pectin - at the dentate line)
- IBD
- may begin during an episode of loose stool, or often spontaneously with no obvious precipitating factor
- opiate analgesia is a/w constipation and a subsequent increased incidence of anal fissure
- STIs e.g. HIV, syphilis, herpes
- may be an ischaemic ulcer with spasm of the IAS
therefore risk factors are:
- hard stools
- pregnancy
- opiate analgesia
- IBD
- STIs
Anal fissure - clinical features
- pain on defecation = severe pain, ‘like passing broken glass’, can also be burning. Occurs immediately after bowel movements and improves with time
- tearing sensation on passing stool
- fresh blood on stool or on paper
- anal spasm and tenderness of examination
- symptoms tend to come and go (intermittent)
- clinical Dx
Anal fissure - management
- conservative: high-fibre diet, adequate fluid intake, sitz baths, topical analgesia, lubricant before defecation (petroleum jelly)
- laxatives: bulk forming laxatives 1st line, lactulose 2nd line, stool softener
- topical glyceryl trinitrate (GTN) or topical diltiazem
- resistant fissures = botulinum toxin injection or surgical sphincterotomy
- The main complication is faecal incontinence
Anorectal abscess - definition
infection of the soft tissues around the anus. Severe perianal pain and swelling are the most common presenting complaints. Rarely, patients may present with life-threatening sepsis from an associated necrotising soft-tissue infection.
Anorectal abscess - aetiology
The majority result from infections of the anal glands (cryptoglandular infections). The anal canal has 6 to 14 glands that lie between the sphincters. Ducts from these glands pass through the internal sphincters and drain into the anal crypts at the dentate line. These glands may become infected when a crypt is occluded by impaction of food matter, by oedema from trauma secondary to a hard stool or foreign body, or as a result of an inflammatory process such as Crohn’s
Anorectal abscess - clinical features
- RF: anal fistula, Crohn’s disease, male gender
- perianal pain
- perianal or rectal induration
- perianal swelling
- low-grade fever and mild tachycardia
- On examination, there will be a erythematous, fluctuant, tender perianal mass, which may be discharging pus or have surrounding cellulitis.
Anorectal abscess - investigations
- often clinical Dx with rectal examination
- occasionally examination under anaesthetic is required
- FBC (leukocytosis), inflamm markers, culture
Anorectal abscess - management
- Abx as per local protocol
- analgesia
- surgical incision and drainage of abscess
- Once drained, proctoscopy to check for any fistula. If present –> insert seton
- postoperative care: warm baths, high fibre diet, fluids
Anal fistula - definition
Chronic abnormal communication between the epithelialised surface of the anal canal and usually the perianal skin. Anal fistulae commonly occur in people with a history of anal abscesses. They can originate in anal glands when anal abscesses do not heal properly
(can also be 2ary to other infection eg crohn’s)
Anal fistulae - types
Park Classification
- Extrasphincteric: begin at the rectum or sigmoid colon and open into the skin surrounding the anus (a/w crohns or appendiceal or diverticular abscesses)
- Suprasphincteric: begin between the sphincters, extends above levator ani and opens near the anus
- Transphincteric: begin between the sphincters and crosses the EAS and opens near anus
- Intersphincteric: begin between the sphincters and crosses the IAS and opens very close to the anus
Anal fistula - clinical features
- skin maceration (softening and breaking down)
- pus, serous fluid and/or (rarely) feces discharge — can be bloody or purulent
- pruritus ani — itching
- recurrent perianal abcesses
- pain, swelling, tenderness, fever, unpleasant odor
- clinical Dx: could see opening on the skin, or redness, induration, discharge etc.
Anal fistula - management
Proctoscopy or MRI (complex fistulas)
“SNAP”
- think Sepsis, address Nutrition, define Anatomy, plan Procedure
(majority heal on their own without procedure)
- fistulotomy - superficial disease (cutting along the whole length of the fistula to open it up so it heals as a flat scar)
- seton techniques - high tract disease (if crosses a significant portion of anal sphincters): surgical thread that is left in the fistula for several weeks to keep it open
- other: ligation of the intersphincteric fistula tract (LIFT) procedure, fibrin glue injections
Anal fistula surgery - complications
- infection
- recurrence of fistula
- bowel incontinence
Haemorrhoids - complications
- anaemia
- thrombosis (sudden onset of perianal pain and the appearance of tender nodule adjacent to anal canal)
- incarceration of prolapsing haemorrhoidal tissue –> urgent haemorrhoidectomy
- bowel incontinence
- pelvic sepsis
- anal stenosis