Perianal Flashcards
How long is the rectum and anal canal?
Rectum = 12cm, anal canal = 4cm
Where does the rectum begin and end?
Sacral promontory to levator ani muscle
What forms the rectum’s continuous muscle layer?
The 3 tenia coli fusing around the rectum
Where does the anal canal begin and end?
Levator ani muscle to anal verge
What kind of epithelium is in the anal canal?
Upper 2/3 - columnar
Lower 1/3 - squamous
Is the anal canal sensate or insensate?
Upper 2/3 is insensate, lower 1/3 is sensate
What is the blood supply to the anal canal?
Upper 2/3: superior rectal artery and vein
Lower 1/3: middle and inferior rectal arteries and veins
Which lymph nodes does the anal canal drain to?
Upper 2/3 - internal iliac nodes
Lower 1/3 - superficial inguinal nodes
What are the dentate and white lines of the anal canal?
Dentate - squamomucosal junction
white - where anal canal becomes true skin
What’s the difference between the internal and external anal sphincters?
- Internal
- Thickening of rectal smooth muscle
- Involuntary
- External
- Three rings of skeletal muscle (deep, superficial, subcutaneous)
- Voluntary
Where is the anorectal ring located and what is it composed of?
Deep segment of the external sphincter which is continuous with the puborectalis muscle (part of levator ani). Palpable on PR about 5cm from the anus.
Demarcates teh junction between teh anal canal and the rectum and must be preserved to maintain continence
Define perianal haematoma
How does a perianal haematoma present?
- Tender blue lump at the anal margin
- Pain worsened by defecation or movement
How is a perianal haematoma treated?
Analgesia and wait for spontaneous resolution, or can be evacuated under local
How does proctalgia fugax present?
- Young, anxious men
- Crampy anorectal pain which is worse at night
- Unrelated to defecation
- Associated with trigeminal neuralgia
How is proctalgia fugax treated?
Reassurance
GTN cream
What are the 2 most common kinds of perineal warts and who are they common in? How are they treated?
MSM:
- Condylomata accuminata:
- HPV
- Podophyllin paint, cryo, surgical excision
- Condylomata lata
- Syphilis
- Penicillin
What are the causes of pruritus ani?
- 50% idiopathic
- Poor hygiene
- Haemorrhoids
- Anal fissure
- Anal fistula
- Fungi
- Worms
- Crohn’s
- Neoplasia
What are haemorrhoids?
Disrupted and dilated anal cushions
What is the pathophysiology of haemorrhoids?
- Anal cushion = mass of spongy vascular tissue.
- Gravity and straining cause engorgement and enlargement of the anal cushions
- Hard stool disrupts connective tissue around cushions
- Cushions protrude and can be damaged by hard stool causing bright red bleeding (capillary)
Where do haemorrhoids tend to be positioned and why?
At 3, 7 and 11 o’clock because this is where the three major arteries that feed the vascular plexused enter the anal canal
What are the causes of haemorrhoids?
- Constipation with prolonged straining
- Venous congestion can contribute:
- Pregnancy
- Abdominal tumour
- Portal hypertension
How do you classify haemorrhoids?
- 1st degree: never prolapse
- 2nd: prolapse on defecation but spontaneously reduce
- 3rd: prolapse on defecation but require digital reduction
- 4th: remain permanently prolapsed
How do haemorrhoids present?
- Fresh painless PR bleeding
- Bright red
- On paper, on stool, may drip into pan
- Pruritus ani
- Lump in perianal area
- Severe pain = thrombosis
- Discharge - faecal soiling or mucus - because they prevent complete anal closure
What causes thrombosis of haemorrhoids?
Gripping by the anal sphincter (can ulcerate or infarct)
What investigations should be done for suspected haemorrhoids?
- Full abdo exam and palpate for masses
- Inspect perianal area: masses, recent bleeding
- DRE: can’t palpate them unless they’re thrombosed
- Rigid sig to identify higher rectal pathology
- Proctoscopy (also allows treatment)
What are the differentials for haemorrhoids?
- Perianal haematoma
- Fissure
- Abscess
- Tumour (must exclude in all cases)
What are the conservative management options for haemorrhoids?
- Increase fibre and fluid intake
- Stop straining at stool
- May resolve on its own
What are the medical management options for haemorrhoids?
- Topicals
- Anusol: hydrocortisone
- Topical analgesics
- Laxatives: lactulose, fybogel
What are the interventional management options for haemorrhoids?
- Injection with sclerosant (5% phenol in almond oil)
- Injection above dentate line
- SE: impotence, prostatitis
- Barron’s banding -> thrombosis and separation
- SE: bleeding, infection
- Cryotherapy
- SE: watery discharge post procedure
- Infra red coagulation
Describe the surgical management options for haemorrhoids
Haemorrhoidectomy
- Excision of piles and ligation of vascular pedicles
- Lactulose + metronidazole 1 week post op
- Discharge with laxatives post op
- SE: bleeding, stenosis
How are thrombosed piles managed?
- Analgesia
- Ice packs
- Stool softeners
- Bed rest with elevated foot of bed
- Pain usually resolves in 2-3 weeks
- Haemorrhoidectomy is not usually necessary
Define anal fissure
Tear of squamous epithelial lining in lower anal canal
What causes anal fissures?
- Mostly trauma secondary to the passage of hard stool
- Associated with constipation
- Spasm of internal anal sphincter contributes to pain and leads to ischaemia and poor healing
- Commoner in women
- Rarer causes, often leading to multiple ± lateral fissures:
- Crohn’s
- Herpes
- Anal cancer
- Poor blood supply can perpetuate
How do anal fissures present?
- Intense anal pain especially on defecation
- May prevent patient from passing stool
- Fresh rectal bleeding mostly on paper
- Constipation
- Rarely discharge of small amounts of pus
What investigation findings are consistent with an anal fissure?
- PR often impossible
- Midline ulcer seen
- Usually posterior at 6 oclock
- May be anterior
- May be a mucosal tag -> sentinel pile
- Usually posterior at 6 oclock
- Groin LNs suggest a complicating factor e.g. HIV
What are the indications for an EUA for an anal fissure?
Fissure is recurrent, chronic or difficult to treat
What are the conservative management options for haemorrhoids?
- Soaks in warm bath
- Toileting advice
- Dietary advice: increase fibre and fluids
What are the medical management options for haemorrhoids?
- Laxatives: lactulose + fybogel
- Topical -> resolution in 75%
- Lignocaine
- GTN
- Diltiazem
- Botulinum injection
Describe the surgical management options for haemorrhoids and the possible complications
Lateral partial sphincterotomy
- Division of internal anal sphincter at 3 o’clock
- Pre-op anorectal US and manometry
- Complications
- Minor faecal/flatus incontinence (=GTN)
- Perianal abscess
What was Lord’s operation and why isn’t it used anymore?
Anal dilatation under anaesthetic for anal fissure - no longer used because of high rates of incontinence
Define fistula in ano
Abnormal connection between the ano rectal canal and the skin
What is the pathogenesis of fistula in ano?
- Usually secondary to perianal sepsis
- Blockage of intramuscular glands -> abscess
- Abscess discharges to form fistula
Which conditions are associated with fistula in ano?
- Crohn’s
- Diverticular disease
- Rectal cancer
- Immunosuppression
How do you classify anal fistulas?
- High: cross sphincter muscles above dentate line
- Low: don’t cross sphincter muscles above dentate line
What is Goodsall’s rule?
- Determines path of anal fistula dract
- Fistula anterior to anus track in a straight line (radial)
- Fistula posterior to anus always have an internal opening at the 6 o clock position - curved track
How do anal fistulas present?
- Persistent anal discharge
- Perianal pain or discomfort
What examination findings are consistent with an anal fistula?
- May visualise external opening ± pus
- Induration around the fistula on DRE
- Proctoscopy may reveal internal opening
What investigations should you order in a suspected anal fistula?
MRI and endoanal USS
How are anal fistulae managed?
- Extent of fistula must be delineated first by probing the fistula at EUA
- Low fistula
- Fistulotomy and excision, laid open to heal by secondary intention
- High fistula
- Fistulotomy could damage the anorectal ring
- Suture - a seton - is passed through the fistula and gradually tightened over months
- Stimulates fibrosis of tract
- Scar tissue holds sphincter together
What is the pathogenesis of perianal abscess?
- Anal gland blockage -> infection -> abscess
- E.g. e coli, bacteroides
- May develop from skin infections e.g. sebaveous gland, staphs
Which conditions are associated with perianal abscess?
- Crohn’s
- DM
- Malignancy
How do you classify perianal sepsis/abscessesand what distinguishes them clinically?
- Perianal: 45%
- Discrete local red swelling close to the anal verge
- Ischiorectal: <30%
- Systemic upset
- Extremely painful on DRE
- Intersphincteric/intermuscular >20%
- Pelvirectal/supralevator - ~5%
- Systemic upset
- Bladder irritation
How does a perianal abscess present?
- Perianal mass or cellulitic area
- Fluctuant mass on PR
- Septic signs: fever, tachycardia
How do you treat a perianal abscess?
- Antibiotics may suffice if treatment started very early in course
- Most cases require EUA with I&D
- Wound packed
- Heals by secondary intention
- Daily dressing for 7-10 days
- Look for an anal fistula which complicates ~30% of abscesses
What is a sinus?
A blind ending tract, lined by epithelial or granulation tissue, which opens onto an epithelial surface
What is the pathophysiology of pilonidal sinus?
- Hair works its way beneath the skin
- Foreign body reaction
- Formation of abscess
- Usually occurs in the natal cleft
What are the risk factors for a pilonidal sinus?
- M>F 4:1
- Mediterranean, Middle East, Asians
- Often overweight with poor personal hygiene
- Occupations with lots of sitting - e.g. truck drivers
How does a pilonidal sinus present?
- Persistent discharge of purulent or clear fluid
- Recurrent pain
- Abscesses
How do you treat a pilonidal sinus?
- Conservative
- Hygiene advice
- Shave/remove hair from affected area
- Surgical
- Incision and drainage of abscesses
- Elective sinus excision
- Methylene blue to outline tract
- Recurrence in 4-15%
How common is anal carcinoma?
Relatively uncommon - 250-300/year in the UK
What kinds of cancer occur in the anal canal & margin?
- 80% SCCs
- Melanomas
- Adenocarcinomas
What are the features of anal margin tumours compared to anal canal?
- Well differentiated keratinising lesions
- Commoner in men
- Good prognosis
What are the features of anal canal tumours compared to anal margin?
- Arise above dentate line
- Poorly differentiated, non-keratinising
- Commoner in women
- Worse prognosis
Where do anal carcinomas spread to?
- Above dentate line -> internal iliac nodes
- Below dentate line -> inguinal nodes
What is the aetiology of anal carcinoma?
- HPV (16, 18, 31, 33) is an important factor
- Increased incidence in MSM
- Increased incidence of perianal warts
How do anal carcinomas present?
- Perianal pain and bleeding
- Pruritus ani
- Faecal incontinence
- 70% have sphincter involvement at presentation
- May lead to rectovaginal fistula
- Mucus discharge
What are the examination findings in anal carcinoma?
- Palpable lesion in only 25%
- ± palpable inguinal LNs
What investigations should you do in anal carcinoma?
- Low Hb (ACD)
- Endoanal US
- Rectal EUA and biopsy
- CT/MRI: assess pelvic spread
How do you manage anal carcinoma?
- Chemoradiotherapy: most patients
- 50% 5 years
- Surgery
What are the indications for surgery in anal carcinoma?
- Tumours that fail to respond to radiotherapy
- GI obstruction
- Small anal margin tumours without sphincter involvement
Define rectal prolapse
Protrusion of rectal tissue through the anal canal
How do you classify rectal prolapses and how are they different clinically?
- Type 1: mucosal prolapse
- Partial prolapse of redundant mucosa
- Common in children especially with CF
- Essentially large piles - same risk factors
- Type 2: full thickness prolapse
- Commoner than type 1
- Usually elderly females with a poor O&G history
How does rectal prolapse present?
- Mass extrudes from rectum on defecation
- May reduce spontaneously or require manual reduction
- May become oedematous and ulcerated
- Causing pain and bleeding
- Faecal soiling
- Associated with vaginal prolapse and urinary incontinence
What examination findings are consistent with a rectal prolapse?
- Visible prolapse: brought out on straining
- ±Excoriation and ulceration
- Decreased sphincter tone on PR
- Associated uterovaginal prolapse
What investigations should you do in a suspected rectal prolapse?
- Sigmoidoscopy to exclude proximal lesions
- Anal manometry
- Endoanal US
- MRI
What are the treatment options for a partial rectal prolapse?
- Phenol injection
- Rubber band ligation
- Surgery: Delorme’s procedure
What are the treatment options for a complete rectal prolapse?
- Abdominal approach: rectopexy
- Lap or open
- Mobilised rectum fixed to sacrum with mesh
- Perineal approach: Delorme’s procedure
- Resect mucosa and suture the two mucosal boundaries
