Colorectal Flashcards
Differentiate between an ileostomy and colostomy
Ileostomy V Colostomy
Location : Right iliac fossa V More likely on the left
Appearance: Spouted (to keep irritant contents away from skin) V Flushed
Output: Liquid V Solid
What is a gastrostomy used for? Where is it found?
Use:
Gastric decompression or fixation
Feeding
Site:
Epigastrium
What is a loop jejunostomy used for? Where is it found?
Use:
Seldom used as very high output
May be used following emergency laparotomy with planned early closure
Site: wherever needed
What is a Percutaneous jejunostomy used for? Where is it found?
Use:
Feeding
Site:
LUQ (proximal bowel)
What is a Loop ileostomy used for? Where is it found?
Use:
Defunctioning of colon e.g. following rectal cancer surgery
Does not decompress colon (if ileocaecal valve competent)
Site:
RIF
What is an End ileostomy used for? Where is it found?
Use:
Usually following complete excision of colon or where ileocolic anastomosis is not planned
May be used to defunction colon, but reversal is more difficult
Site:
RIF
What is an End colostomy used for? Where is it found?
Use:
Where a colon is diverted or resected and anastomosis is not primarily achievable or desirable
Site:
Either left or right iliac fossa
What is a loop colostomy used for? Where is it found?
Use:
To defunction a distal segment of colon
Since both lumens are present the distal lumen acts as a vent
Site:
May be located in any region of the abdomen, depending upon colonic segment used
Key features of anal fissures?
Typically presents with painful rectal bleeding
Intense pain post defecation
Location: midline 6 & 12 o’clock position. Distal to the dentate line
Chronic fissure > 6 weeks: triad: Ulcer, sentinel pile, enlarged anal papillae
3 major causes of proctitis?
Crohn’s, ulcerative colitis, Clostridioides difficile
Causes of ano-rectal abscess?
Position?
E.coli, staph aureus
Positions: Perianal, Ischiorectal, Pelvirectal, Intersphincteric
Cause of anal fistula? Location?
Usually due to previous ano-rectal abscess
Intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric. Goodsalls rule determines location
Associations of rectal prolapse?
childbirth and rectal intussceception
Cause of pruritus ani?
Extremely common
In children is often related to worms, in adults may be idiopathic or related to other causes such as haemorrhoids.
Most common anal neoplasm?
Squamous cell carcinoma
Associations of rectal ulcer?
Signs on histology?
Associated with chronic straining and constipation.
Histology shows mucosal thickening, lamina propria replaced with collagen and smooth muscle (fibromuscular obliteration)
Define haematochezia
passage of fresh blood per rectum
generally caused by bleeding from the lower GI tract
Common causes of acute lower GI bleeding?
diverticular disease
ischaemic / infective colitis
haemorrhoids
malignancy
angiodysplasia
Crohn’s disease / UC
radiation proctitis
What is the most common cause of lower GI bleeding?
Diverticulosis
Diverticula are outpouchings of the bowel wall that are composed only of mucosa, most commonly in the descending and sigmoid colon
What are haemorrhoids?
pathologically engorged vascular cushions in the anal canal that can present as a mass, with pruritus, or fresh red rectal bleeding
Key questions to ask in a hx for a PR bleed?
Nature of bleeding – duration, frequency, and colour, and whether related to stool and defecation
Associated symptoms – including pain (especially association with defaecation), any haematemesis or melena, any PR mucus, previous episodes, or weight loss
Family history – bowel cancer or inflammatory bowel disease
What score can be used to help stratify patients presenting with a lower GI bleed to determine if outpatient management is feasible?
The Oakland Score
Factors used:
Age, Sex, Previous Admissions for Lower GI bleeding, PR findings, Heart Rate, Systolic BP, and Hb Concentration.
Investigations for rectal bleeding?
If unstable?
FBC, U&Es, LFT, clotting profile
Group and Save
Stool cultures to exclude infective causes
Further investigations:
colonoscopy to exclude left-colonic pathology (especially malignancy)
if no abnormality on colonoscopy = OGD
If haemodynamically unstable:
resuscitate using blood products and correct any coagulopathy
urgent CT angiogram (before any endoscopic therapy)
Key risk factors for adverse outcomes from any acute rectal bleeding?
haemodynamic instability
ongoing haematochezia
age >60yrs
serum creatinine >150µmol/L
significant co-morbidities
Management of rectal bleeding?
95% settle spontaneously
unstable rectal bleeding = urgent resuscitation
- wide bore IV access and blood products and urgent reversal of any anticoagulation
any patient with a Hb <70g/L (or <80g/L in those with CVD) requires transfusion
Further management:
Endoscopic haemostasis methods: injection (diluted adrenaline), contact and non-contact thermal devices, and mechanical therapies (endoscopic clips and band ligation)
Arterial embolisation- patients with an identified bleeding point (“blush”) of sufficient size on angiogram
What is the aetiology of colorectal cancer?
most commonly adenocarcinoma
“adenoma-carcinoma sequence”:
progression of normal mucosa > colonic adenoma (polyps) > invasive adenocarcinoma
What genetic mutations predispose to colorectal cancer?
Adenomatous polyposis coli (APC)
Mutation of the APC gene (tumour suppressor) = growth of adenomatous tissue, such as Familial Adenomatous Polyposis (FAP)
Hereditary nonpolyposis colorectal cancer (HNPCC)
Mutation to HNPCC (DNA mismatch repair gene) = defects in DNA repair, such as Lynch syndrome
Risk factors for colorectal cancer?
75% are sporadic
older male
fam hx (present in 10–20% of all patients)
inflammatory bowel disease
low fibre diet and high processed meat intake
smoking and alcohol
Clinical features of bowel cancer?
Common : change in bowel habit, rectal bleeding, WL, abdo pain, and symptoms of iron-deficiency anaemia
Right-sided colon cancers – abdo pain, iron-deficiency anaemia, palpable mass in RIF, often present late
Left-sided colon cancers – rectal bleeding, change in bowel habit, tenesmus, palpable mass in left iliac fossa or on PR exam
Which patients should be referred for urgent investigations for bowel cancer?
≥40yrs with unexplained weight loss and abdominal pain
≥50yrs with unexplained rectal bleeding
≥60yrs with iron‑deficiency anaemia or change in bowel habit
Positive occult blood screening test
Major differentials for colorectal cancer?
Inflammatory bowel disease – The average age of onset is younger (20-40yrs) than with colorectal cancer and typically presents with diarrhoea containing blood and mucus
Haemorrhoids – Bright red rectal bleeding on the pan or surface of the stool but rarely presents with abdo pain, altered bowel habits, or weight loss
What colorectal cancer screening is offered in the UK?
FIT tests every 2 years for people aged 60-75
Investigations for colorectal cancer?
FBC (anaemia) LFTs and clotting
CEA should NOT be used as a diagnostic test (poor sensitivity and specificity) but can be used to monitor disease progression
(elevated baseline CEA = worse prognosis)
gold standard for diagnosis of colorectal cancer is via colonoscopy with biopsy
Once diagnosis made:
CT CAP: distant mets and local invasion
MRI rectum: (for rectal cancers) to assess depth of invasion and need for pre-op chemo
Endo-anal USS : (for early rectal cancers, T1 or T2 only) to assess suitability for trans-anal resection
When would you use a Right Hemicolectomy or Extended Right Hemicolectomy?
caecal tumours or ascending colon tumours
extended option for any transverse colon tumours
During the procedure the branches of the SMA (ileocolic, right colic, and right branch of the middle colic) are divided and removed with their mesenteries
When would you use a Left Hemicolectomy?
descending colon tumours
the left branch of the middle colic vessels (branch of SMA/SMV), the inferior mesenteric vein, and the left colic vessels (branches of the IMA/IMV) are divided and removed with their mesenteries
When would you use a Sigmoidcolectomy?
sigmoid tumour
IMA is fully dissected out with the tumour in order to ensure adequate margins are obtained