The Anus Flashcards
Anal anatomy zones
Distal zone-> squamous mucotaneous junction to dentate line
- non keratinising squamous epithelium
- very sensitive
Transitional zone-> variable 0.3-2cm
- transitional epithelium, squamous to columnar
- anal glands in sub mucosa
- surrounded by external anal sphincter
Dentate line-> bellow the anal columns
Columns of morgani
- 6-10 longitudinal folds
- contain a terminal branch of the superior rectal artery and vein
- L lateral, R posterior and R anterior most prominent
- form the anal cushions-> fine control of continence
Columnar mucosal zone
- relatively insensitive
- darker reddish blue
Faecal continence
Internal sphincter + external sphincter + puborectalis
1) distension of rectum by flatulus/faeces
2) reflexive small relaxation of internal sphincter
3) small amount of contents in to in to anal canal
4) increased pressure in rectum and relaxation of continue muscles
5) defecation
6) increased electrical activity keeps sphincter closed
* if inconvenient sphincters contract and contents of anal canal returns to rectum
Haemorrhoids definition
Pathological enlargement of columns of morgani
Haemorrhoids risk factors
Familial predisposition
Pregnancy
Constipation
Diarrhoea
Haemorrhoids pathology
Initiated by straining to pass hard stool
- increased intrauterine abdo pressure
- obstruction of venous return
- venous plexus becomes enlarged
- bulging mucosa dragged distally by hard stool
Haemorrhoids classification
Internal-> above the dentate line
External-> bellow the dentate line
Grade 1-> never prolapse
Grade 2-> prolapse during defecation and then return spontaneously
Grade 3-> remain prolapsed unless manipulated digitally
Haemorrhoids clinical features
Intermittent Days to weeks Precipitated by constipation Red bleeding-on loo role but may also spurt/drip Pruritis ani Discomfort on defecation Perianal discharge 'Something coming down'
Not palpable unless very large-> visible on protoscopy
Haemorrhoids complications
Prolapse Thrombosis -acute pain with oedematous purple mass-> ice and laxatives Strangulation Anaemia Skin tags Anal polyps
Haemorrhoids management
Increased fluids and fibre Creams-> treat itch and decrease inflammation/bacteria Avoid straining Sclerosant injections Bonding around neck Haemorrhoidectomy
Perianal infection causes
Infection of anal fissure
STI
Blocked anal glands
Perianal infection pathology
1) infection in crypto glandular epithelium
2) internal sphincter breached through crypts of morgani -> inter sphincters space
Downwards spread-> Perianal abcess 80%
Outwards spread-> ischiorectal abcess 15%
Upwards spread-> superiolateral abcess 5%
Perianal infection risk factors
DM Immunocomprimised Anal sex IBD Diverticulitis Male 20-60y
Perianal infection clinical features
3-4 days of pain and difficulty defecating
Pus from rectum
Constipation
Perianal-> painful, red swelling close to anal verge
Ischiorectal-> sepsis, perianal pain, tender over ischiorectal fossa, later mass on DRE
Superolateral-> sepsis, rectal pain, difficulty with micturition
Fistula in ano definition
Pus buries through the wall of the anal canal
-> induration on DRE
Perianal infection management
Draining, no antibiotics
Send pus for micro-> gut bacteria means fistula
Differentials of rectal bleeding
Haemorrhoids, most common Anal fissure Fistula in ano Diverticular disease IBD Colonic polyps Colon cancer
Perianal haematoma
Thrombosis in a subcutaneous vein bellow the transitional zone
Discrete painful swelling
Should resolve
Fissure in ano definition
Longitudinal tear in the Mucosa and skin of the anal canal, distal to the dentate line
Commonly posterior midline
Fissure in ano clinical features
Pain which is worse when defecating and continues after Small amount of fresh blood Sphincter spasm Constipation due to fear of pain Less painful when chronic
Tear in midline of the posterior margin
Skin tag
Tenderness
Fissure in ano management
GTN creams-> relax sphincter and increase blood supply
Botox injection
Lateral internal sphincterectomy
Anal cancers
4% of large bowel cancers
>80% squamous
Causes:
- HPV 16 and 18
- intraepithelial neoplasia
- HIV/immunocomprismised
Symptoms:
- rectal bleeding
- perianal pain
- pruritis
- incontinence
- mucous discharge
- inguinal lymphadenopathy
Management:
- biopsy and CT
- MRI
- small WLE
- large radio +- chemo
