Colorectal Flashcards
Blood supply to the appendix
Appendicular artery
terminal branch of ileocolic artery - branch of the SMA
Things that can obstruct an appendix
- faecoliths
- calculi
- lymphoid hyperplasia
- infection
- tumour
Pathogenesis of appendicitis
- obstruction
- increased luminal and intramural pressure
- thrombosis and occlusion of small vessels and stasis of lymph
- activation of visceral nerves T8-T10 = central pain
- parietal inflammation = localised pain
Classical signs and symptoms of appendicitis
- RLQ pain
- anorexia
- nausea and vomiting
Differentials for appendicitis
- UTI
- renal calculi
- gastroenteritis
- rupture ovarian cyst
- PID
- cholcystitis
3 Eponimous clinical signs in appendicitis
- Rovsing’s sign
- Obturator sign
- Iliopsoas sign
Rovsing’s sign
Palpation of the lower left quadrant elicits pain in the right lower quadrant
Obturator sign
Pain with internal rotation of the hip (pelvic appendix)
Iliopsoas sign
Extension of the right hip elicits pain in the right hip (retrocecal appendix)
U/S findings in appendicitis
Want to exclude pelvic pathology
- thickened wall >2mm
- increased appendix diameter >6mm
- free fluid
CT findings in appendicitis
- thick wall
- appendix diameter >7mm
- appendicolith/abscess
- free fluid
Management of appendicitis
- admission
- IV fluid + analgesia
- if confident, appendectomy
- investigation
- diagnostic lap for young women
What is an appendicular mass?
> 5 days of symptoms
Findings in RLQ
palpable mass
Treatment of appendicular abscess
CT/US-guided percutaneous drainage
Definition of a volvulus
A loop of bowel and its mesentery twist on a fixed point at its base
Causes obstruction
Pathophysiology of volvulus
- torsion and obstruction
- gas an fluid production
- loop distends
- fluid and electrolyte loss
How does volvulus progress to gangrene?
- obstruction of mesenteric blood flow
- increased intraluminal pressure obstructs venous and arterial obstruction
Subserosal petechiae - blood stained ascites
- gangrene
Most common volvulus sites
- sigmoid
- caecum
Less common volvulus sites
- transverse colon
- splenic flexure
- descending colon
Risk factors for sigmoid volvulus
- long sigmoid and mesocolon with narrow mesenteric attachements
- chronic constipation
- high fibre diet
- use of enemas
- altitude
Difference between endemic and sporadic volvulus
Endemic patients have increased blood supply and so present less with gangrene and more with fluid sequestration
Presenting features of sigmoid volvulus
- recurrent abdo distention
- constipation
- pain
- dyspnoea
Investigations to diagnose sigmoid volvulus
- upright abdo XRAY
- barium enema (bird’s beak)
- CT (whirl)
XRAY findings in sigmoid volvulus
- bent inner tube
- coffee bean sign
- summation light
- liver overlap sign
Contraindications to sigmoidoscopy with sigmoid volvulus
- gangrene
- compound volvulus
When to do an urgent lap for volvulus
- failed decompression
- features of peritonitis
- gangrene
What is an ileo-sigmoid knot?
- volvulus of both small and large bowel
Two types of caecal volvulus
- axial ileo-colic volvulus
- caecal bascule
Signs and symptoms of a caecal volvulus
- abdo pain and distension
- constipation/obstipation
- vomiting
XRAY findings in a caecal volvulus
- single fluid level in a dilated caecum
- absence of gas in the distal colon
3 types of urgent surgery for a caecal volvulus
- right hemicolectomy
- caecopexy
- caecostomy
Definition of a polyp
A localised elevated lesion arising from an epithelial surface
Types of adenomatous polyps
- villous adenoma
- tubular villous adenoma
Evidence for the polyp-cancer sequence
- polpectomy decreases cancer incidence
- colonic adenomas occur more frequently with cancers
- large adenomas are more likely to have cancer
- severe dysplasia in polyps progresses to cancer
- residual adenomatous tissue is found in invasive cancers
- 100% of FAP develop cancer
- high rate of adenomas where there is a high cancer rate
Symptoms of polyps
- bleeding
- mucus
- prolapse
When to follow up a polyp patient
- high risk: 2-3 years
- low risk: 4-5 years
Types of polyp syndromes
- Juvenile polyp
- Juvenile polyposis
- Peutz-Jeglers polyposis
- FAP
Where is the mutation in FAP?
APC gene on chromosome 6
What is Gardener’s syndrome?
FAP with extra-intestinal features
Extra-intestinal features of Gardener’s syndrome
- osteomata of the skull
- epidermoid cyst
- soft tissue skin tumours
- dental abnormalities
Other associations with FAP
- desmoid tumours
- Congenital hypertrophy of retinal pigment epithelium
- malignant lesions
3 prophylactic surgeries for FAP
- proctocolectomy
- colectomy with ileo-rectal anastomosis
- restorative proctocolectomy
What is a diverticulum?
A sac-like protrusion of colonic wall
How do patients with diverticuli present?
- asymptomatic
- symptomatic
- diverticular bleed
- diverticulitis
Complications of diverticuli
- abscess
- fistula
- peritonitis (purulent/faeculent)
- stricture and obstruction
Explain the Hinchey classification for diverticuli
Stage 1 = pericolic/mesenteric abscess
Stage 2 = walled-off pelvic abscess
Stage 3 = generalised purulent peritonitis
Stage 4 = generalised faeculent peritonitis
How does diverticular haemorrhage present?
- abrupt and painless bleeding
- potentially life-threatening
- mostly from the right colon
Potential etiology of IBD
- genetic predisposition
- infection
- hypersensitivity
Pathological features of UC
- usually in the colon
- continuous
- involves the rectum
- involves the mucosa
- crypt abscesses
- smoking is protective
Pathological features of Crohns
- found usually in terminal ileum and proximal colon
- patchy with skip lesions
- deep fissuring ulcers that penetrate through the wall
- non-caseating granulomas
- smoking = risk factor
Definition of an acute severe attack of UC
6 or more stools a day with 2 or more of:
- pyrexia
- anaemia
- tachycardia
Initial management of IBD
- resus
- confirm Dx with rigid/flexi (NOT C-SCOPE)
- stool cultures
- daily chest and abdo XRAY
- 2x daily Dr assessement
- high dose IV steroids
- after 3-5 days: surgery/rescue therapy
Medical rescue therapy for IBD
- cyclosporine
- anti-TNF therapy
When do you need to do emergency surgery for IBD?
- toxic megacolon
- colonic perforation
- massive haemorrhage
When do you need to do urgent surgery for IBD?
Failed medical therapy
When do you need to do elective surgery for IBD?
- chronic ill health
- risk of malignancy
Operations for UC
- proctocolectomy with removal of anus and permanent end ileostomy
- restorative proctocolectomy
- colectomy and ileostomy
- colectomy and ileorectal anastomosis
La Place’s Law
As the radius increases with a constant pressure, the tension exerted on the wall will increase
Etiology of large bowel obstruction
- colorectal cancer
- volvulus
- diverticular stricture
- Other (fecal impaction, hernia, foreign body)
Differential diagnoses for large bowel obstruction
- small bowel obstruction
- ileus
- Hirschsprungs
- colonic pseudo-obstruction
- congenital leiomyopathy
- toxic megacolon
Presenting features of large bowel obstruction
- early onset obstipation and distension
- mild abdo pain
- vomiting (late)
Investigations for large bowel obstruction
- Abdo XRAY
- water soluble contrast enema
- CT-scan with rectal contrast
XRAY features of small bowel
- central
- linea coniventes
XRAY features of large bowel
- peripheral
- haustral markings
Operation for a R-sided obstruction
- midline lap +
- R hemicolectomy/ extended R hemicolectomy
- primary anastomosis
Operations for a L-sided obstruction
- 3 stage (for rectal cancer)
- 2 stage (for obstructing sigmoid cancer)
- 1 stage (for young patients with good sphincters)
Definition of a lower GIT bleed
- bleeding that occurs distal to the ligament of Treitz
Presentation of lower GIT bleed
- acute
- chronic
- occult
Features of a massive LGIB
- large amounts of red/ maroon blood
- haemodynamic shock/instability
- Hb of 8 or less
- need to transfuse >2 U of blood
- bleeding continues for 3 days
- significant rebleed within 1 week
Most common causes of LGIB
- diverticulosis
- angiodysplasia
- colitis
- neoplasia
- haemorrhoids etc
- drug-related
Radiology options for LGIB
- abdo X-ray
- CT with mesenteric angiography
- Technetium-labeled RBC scanning
- selective mesenteric angiography
Other investigations for a LGIB
- endoscopy
- colonoscopy
Ways to achieve haemostasis in a LGIB
- colonoscopy (coag, haemoclip, injecion)
- formal angiography (trans cath embolization)
- surgery
Pre-op management of anal sepsis
- diagnosis
- exclusion of other pathology
- determine anatomical extent
Diseases associated with anorectal sepsis
- Crohns
- UC
- hidradenitis suppurativa
- carcinoma of anus/ lower rectum
- TB
- pelvic sepsis
- foreign bodies
- lymphogranuloma venereum
- actinomycosis
Pathways of anal fistulas
- intersphincteric
- transsphincteric
- suprasphincteric
- extrasphincteric
What is a simple fistula?
- one opening and easily identifiable primary tract
What is a complex fistula?
- multiple external openings and secondary tracts
Symptoms of an acute anal abscess
- pain worsening over a few days
- worse with defeacation
- fever
- discharge/ painful swelling
Who needs inpatient treatment for an anal abscess?
- very large abscess
- immunocomp
- diabetic/systemically unwell
How to drain an abscess
- under GA
- EUA and rigid (exclude rectal disease)
- incision at max flux
- pus swab
- break loculi
- trim edges
- saline soaked gauze, dry pad and disposable panty
Surgical management of a fistula
- lay open the primary tract
- drain secondary tracts
- create a wound that’s easy to dress
- preserve continence
Goodsall’s rule
- anerior fistulas tend to be straight and radial
- posterior fistulas are more likely to be complex, but usually have a midline internal opening
Features of a thrombosed perianal varix
- sudden onset pain
- worse when walking/sitting
- pain subsides over 10 days
- obvious tender lump covered by stratified squamous epithelium
- bluish and rubbery
Function of a temporary stoma
To assume the function of elimination of waste, to permit healing or rest the gut or section of bowel
Function of a permanent stoma
To take over the function of elimination of the bowel that has been removed or permanently bypassed
Three classifications of stomas
- input stomas
- diverting stomas
- output stomas
Examples of input stomas
- gastrostomy
- jejenostomy
Examples of diverting stomas
- ileostomy
- loop colostomy
Examples of output stomas
- bladder/bowel
Indications for stoma surgery
- congenital
- acquired
- traumatic
- infective
- neoplastic
Most commonly created output stomas
Faecal: colostomy and ileostomy
Urinary: ileal conduit/ urostomy and nephrostomy
Factors taken into consideration when siting a stoma
- loaction of the rectus muscle
- the waistline/beltline
- hobbies, work, sport, activities
Places to avoid when siting a stoma
- lower costal margins
- planned incisions
- old scars
- obvious creases
- umbilicus
- iliac crests
Types of colostomies
- end colostomy
- loop colostomy
- divided colostomy
- Double-Barrel/ Mikulicsz
Factors influencing stool frequency and consistency
- site in the colon
- precipitating condition or disease process
- previous GIT surgery
- radio/chemotherapy
- medication
- physical status
- eating and drinking habits
Size of ideal colostomy
approx 1cm
Size of ideal ileostomy
approx 3 cm
Things to assess when thinking of doind a stoma
- output/effluent of the stoma
- stool consistency
- condition of the skin
- diameter of the stoma
- financial consideration
- patient’s ability to manage
- availability of the product
Dermatological complications of a stoma
- faecal contamination
- allergy to tape
- mechanical
- bacterial/fungal infection
Surgical complications of a stoma
- parastomal hernia
- stenosis
- retraction
- prolapse
- peristomal granulation
- bolus obstruction
- stoma separation
- ischaemia
Polyps that are considered high risk for cancer
- large polyps >1cm
- villous lesions
- sessile lesions
- high grade dysplasia
Where are polyps most commonly found?
- in the recto-sigmoid area
Hereditary colorectal cancers
- FAP
- Attenuated FAP
- Lynch syndrome
- MUYTH associated polyposis
Factors in IBD that increase risk of cancer
- greater extent of disease
- evidence of mucosal dysplasia
- sclerosing cholangitis
- family history of cancer
How often should first degree relatives of colorectal cancer patients have a colonoscopy?
10 years prior to age of onset of disease in affected relative
Symptoms of rectal tumours
- mucoid discharge
- alteration in bowel habit
- obstructive symptoms
- perianal pain`
Symptoms of left-sided colonic tumours
- intermittent constipation or diarrhoea
- obstructive symptoms
- bleeding
- LOW
- palpable mass
Symptoms of right-sided colonic tumours
- unexplained anaemia and/or weight loss
- occult faecal blood
- obstructive features uncommon
Diagnosis of colorectal cancer
Only on histological assessment
Investigation of colorectal cancer
- procto-sigmoidoscopy (only for distal lesions)
- colonoscopy (gold standard)
- barium enemas
How to stage a colorectal cancer
- chest XRAY
- U/S (liver, ascites, lymphadenopathy)
- CT
- MRI
- PET
Surgeries for colorectal cancer
- right hemi-colectomy
- left hemi-colectomy
- sigmoid colectomy
- anterior resection and abdomino-perineal resection
Factors that confer poorer prognosis for colorectal cancer
- tumour at surgical margins
- obstructed tumour at presentation
- poorly diff tumour
- inadequate lymph node yield
- perineural invasion
- peritoneal deposits/micromets
When do most recurrences of colorectal cancers occur?
In the first two years following surgery
Tumour markers for colorectal cancers
- carcino-embryonic antigen (CEA
