Colorectal Surgery JC060: Intestinal Obstruction: Colorectal Cancer Flashcards

1
Q

Questions to Intestinal obstruction

A
  1. **Paralytic ileus vs **Mechanical obstruction
    - Small bowel: Mechanical usually
  2. Site + Cause of obstruction
    - ***Small vs Large bowel
  3. Simple / ***Strangulated (blood supply compromised)
    - indication for surgery
  4. What investigations
  5. Treatment
    - conservative?
    - duration
  6. Indications for surgery
  7. Surgical options
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2
Q

***Intestinal obstruction

A

Mechanical obstruction:
- Physical barrier to aboral progress of intestinal contents

Paralytic ileus:
- Failure of peristalsis to propel intestinal contents with no mechanical barrier

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3
Q

***Causes of Paralytic ileus

A

記: Post-op, Peritonitis, Ischaemia, Metabolic, Medication

Intra-peritoneal (insult to peritoneal cavity):
1. **Post-op
2. **
Peritonitis / Intra-abdominal abscess (e.g. perforated ulcer / appendicitis)
3. Inflammatory / Infective conditions
4. ***Intestinal ischaemia (e.g. atherosclerosis)

Retroperitoneal (insult to Retroperitoneal cavity / Autonomic NS controlling peristalsis):
1. **Retroperitoneal haematoma / infection
2. Aortic, Spinal, Urological operations
3. **
Pancreatitis

Extra-abdominal conditions
1. **Metabolic abnormalities
- Electrolyte imbalance
- Sepsis
- Uraemia
- Hypothyroidism
- Lead poisoning
- Prophyria
2. **
Medications: Opioids, Anticholinergics, Antihistamines, Catecholamines
3. Spinal injury / operation

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4
Q

Clinical features of Paralytic ileus

A
  1. Abdominal pain
    - **Diffuse, Constant, Less severe (vs **Colicky pain in Mechanical obstruction)
  2. Abdominal distension
  3. Vomiting
  4. Constipation
  5. **Sluggish / Absent bowel sound (vs **Hyperactive in Mechanical obstruction)
  6. Features associated with cause
    - e.g. peritoneal signs in peritonitis
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5
Q

Mechanical bowel obstruction

A

Pathophysiology:
Proximal bowel distended with gas and fluid
—> Hypersecretion + Loss of fluid to gut / extracellular space / peritoneal cavity
—> **
Pressure buildup (
↑ luminal pressure) + **Bacterial overgrowth in proximal bowel (+ **Edematous bowel wall)
—> **
Compromised blood supply
—> ***Necrosis + Perforation of bowel (accelerated in closed loop / strangulating obstruction)

Classification:
- Partial / Complete
- Acute / Chronic
- Simple (obstruction of lumen, usually at 1 point)
- **Strangulating (blood supply to bowel impaired)
- **
Closed loop obstruction (lumen occlusion in >=2 points)

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6
Q

Clinical features of Mechanical obstruction

A
  1. ***Colicky pain (Gripping pain)
    - if ischaemia —> Constant severe pain
  2. Abdominal distension (depend on level of obstruction)
    - upper level obstruction: less prominent distension
    - colonic obstruction: ***more prominent distension
  3. Vomiting
    - upper level obstruction
  4. Constipation
  5. ***Hyperactive bowel sounds

Severity of each symptom depends on the level of obstruction

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7
Q

History taking of Intestinal obstruction

A
  1. Previous episodes bowel obstruction
  2. Previous Abdominal / Pelvic ***operation
  3. History of **cancer / abdominal / pelvic **radiation —> damage to bowel
  4. History of Abdominal ***inflammatory condition
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8
Q

Physical examination

A
  1. General
    - **Fever
    - **
    Vital signs: Temp, BP, Pulse, RR
    - ***Hydration status
  2. Abdomen
    - Distension (symmetrical / asymmetrical)
    - Tenderness, Guarding, Rebound tenderness (Peritoneal signs)
    - Mass (on deep palpation)
    - **Bowel sound (hyperactive / hypoactive)
    - **
    Hernia (cough impulse)
    - Scars
  3. Rectal + Vaginal examination (+ Urine dipstix + External genitalia)
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9
Q

***Investigations

A
  1. Bedside tests
    - **Urinalysis (Urine R/M: UTI, Microscopic RBC)
    - **
    Pregnancy test
  2. Blood tests
    - CBC + D/C (e.g. **Leukocytosis in strangulation, ischaemic bowel, diverticulitis, acute appendicitis, peritonitis)
    - LRFT
    - Electrolytes
    - **
    Amylase (acute pancreatitis)
    - **ABG (bowel ischaemia: metabolic acidosis, vomiting: alkalosis)
    - **
    VBG (lactate)
    - Clotting profile (planning for invasive procedures)
    - Type and screen (planning for invasive procedures)
  3. Imaging
    - Erect CXR (pneumoperitoneum / free gas under diaphragm: perforated viscus)
  • **Erect + Supine AXR
    —> **
    free gas (pneumoperitoneum)
    —> **dilated bowel (e.g. massive dilatation of colon)
    —> **
    air-fluid levels
    —> **evidence of strangulation:
    ——> thumb printing (large bowel wall thickening)
    ——> pneumatosis cystoides intestinalis (presence of multiple gas-filled cysts in submucosa / subserosa of the small intestine, signify necrotising enterocolitis, impending bowel perforation)
    ——> free peritoneal gas
    —> **
    air in biliary tree
  • USG (pelvis)
  • CT (more sensitive than AXR)
    —> **level of obstruction (transition between dilated and collapsed loop)
    —> lesions (tumour, foreign body)
    —> **
    viability of bowel (by IV contrast)
  • Contrast studies
    —> water soluble contrast
    —> differentiate complete vs partial obstruction
    —> Ba study: precipitate complete obstruction + barium peritonitis
    —> therapeutic effect?
  1. Endoscopy
    - Colonoscopy
    - Upper endoscopy
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10
Q

***Small bowel vs Large bowel obstruction

A

Small bowel obstruction:
- Colicky abdominal pain with **visible peristaltic wave in upper / middle abdomen
- Upper / Epigastric abdominal distension
- **
Early N+V
- ***Severe fluid + electrolyte imbalance
- Metabolic alkalosis

Large bowel obstruction:
- Longer spasm of lower abdomen
- Lower abdominal distension
- **Early constipation
- **
No major fluid + electrolyte imbalance

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11
Q

***Causes of Small bowel obstruction

A

Intraluminal
- Foreign bodies
- Gallstones
- Bezoars (food bolus)
- Worms

Intramural
- Tumour (primary / secondary)
- **
Strictures (
Crohn’s disease, Radiation, Anastomotic, Drug induced)
- *Intussusception (
Gastrointestinal stromal tumor (GIST), Carcinoids, ***Meckel’s diverticulum)

Extramural
- **Adhesions (most common)
- **
Hernia (common in HK)
- ***Volvulus
- Intraperitoneal malignancy (invading the small bowel)

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12
Q

***Management decision

A

Conservative treatment vs Urgent surgery

Conservative (Non-operative) treatment:
1. Partial obstruction
- Adhesions (70% resolved its own)
- Crohn’s disease
- Radiation stricture (unless very tight)
- Disseminated malignant disease (∵ multiple levels of obstruction)

Indications for urgent surgery (記: Perforation, Inflammation, Ischaemia):
1. Incarcerated, **strangulated hernia
2. Suspected / proven strangulation
3. **
Peritonitis
4. **Pneumoperitoneum (indicate viscus perforation)
5. **
Pneumatosis cystoides intestinalis (presence of multiple gas-filled cysts in submucosa / subserosa of the small intestine, signify necrotising enterocolitis, impending bowel perforation)
6. **Closed loop obstruction
7. **
Volvulus (a type of closed loop obstruction) with peritoneal signs

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13
Q

Features suggestive of Strangulation

A
  1. ***↑↑ Abdominal pain (Constant)
  2. ***Blood in vomitus
  3. **Fever, **↑ WBC
  4. Imaging
    - ***Thumb printing (large bowel wall thickening)
    - Loss of mucosal pattern
    - Gas within bowel wall / within Intrahepatic branches of portal vein (may be seen in strangulation)
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14
Q
  1. ***Adhesive obstruction
A
  • Most common cause of small bowel obstruction in western countries
  • Clinical features of small bowel obstruction with previous abdominal surgery
  • Success rate of non-operative treatment: ~50%

Causes:
1. Congenital
2. Post-inflammatory
3. ***Post-abdominal surgery (a defence mechanism after trauma / infection to peritoneal cavity)

Prevention:
1. **Gentle handling of bowel during surgery
2. Removal of powder from gloves
3. **
Anti-adhesive film: Sodium hyaluronate bioresorbable membrane (Seprafilm)
4. Saline lavage
5. ***Minimally invasive surgery

Treatment:
1. Conservative
2. **Gastrografin
3. **
Enterolysis / ***Adhesiolysis

Indications for surgery:
- Non-responsive to conservative treatment (after a few days)
- Clinical features of strangulation

Controversies:
- Duration of conservative treatment
- Administration of ***water soluble contrast (Gastrografin)
—> differentiate partial vs complete obstruction
—> therapeutic effect? (may resolve partial obstruction) reduced operating rate, shorten hospital stay

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15
Q
  1. ***Intussusception
A
  • Mainly in childhood
  • Idiopathic
  • ***IC region
  • Small bowel: **Gastrointestinal stromal tumor (GIST), Carcinoids, **Meckel’s diverticulum, ***Hypertrophic Peyer’s patches
  • Large bowel: cancer
  • Other causes: **Intraluminal polyp, **Lymphoma, ***Peutz–Jeghers syndrome (Polyp in small intestine)

Adults:
- lesion usually found as the leading point
- **pneumatic reduction unlikely useful
- **
surgery usually indicated

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16
Q

***Non-operative treatment

A
  1. ***IV fluid + electrolytes + acid-base balance
  2. ***NG tube decompression
  3. ***Nil by mouth: Nutrition when prolonged fasting anticipated (Parenteral)
  4. Frequent monitor vital signs, abdominal signs, X-ray
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17
Q

***Operative treatment for Small bowel obstruction

A
  1. **Enterolysis / **Adhesiolysis
    - lysis of adhesions + release of constricting band
  2. ***Hernia: Repair
  3. Foreign bodies (Bezoars, Gallstones)
    - **Break down and milk down to colon
    - **
    Enterotomy + removal
  4. ***Bowel resection —> Anastomose with healthy bowel
    - strangulation with gangrenous bowel
    - unhealthy bowel
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18
Q

Clinical features of Resolution of Obstruction

A
  1. Less abdominal distension
  2. Reduction of NG output
  3. Passage of flatus + bowel movement
  4. Resolution in AXR

Unresolved obstruction —> Surgical treatment (duration of Conservative treatment controversial: usually ***48 hours)

Prognosis of Small bowel obstruction:
Mortality:
- Non-strangulating obstruction: 2%
- Strangulating obstruction: 10-30%

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19
Q

***Colonic obstruction

A
  • 15% of IO
  • ***Sigmoid colon usually
  • Lesion at IC valve
    —> can present as Small bowel obstruction
    —> ***Competence of IC valve determines clinical features of distal colon obstruction

Competent IC valve:
- Large bowel shadow

Incompetent IC valve:
- Large bowel + Small bowel shadow

Causes:
1. **Cancer (most common)
2. **
Volvulus
3. Diverticulitis
4. ***Stricture
- Anastomotic
- Radiation
- Ischaemic
- Endometriosis

  1. ***Extrinsic compression
    - Metastasis
    - Pelvic / Extraperitoneal tumour (e.g. PoD tumour)

(6. Faecal impaction
- Digital evacuation)

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20
Q
  1. ***Obstructing Colorectal cancer
A
  • 15-20% Colorectal cancer present with IO

Features:
- More advanced cancer (***>=Stage 2 ∵ through bowel wall)
- Elderly patients with comorbidity
- High operative mortality / morbidity
- Worse prognosis

Diagnosis:
1. Clinical
2. AXR
3. **CT scan
- IV contrast, **
Rectal contrast
—> Site of obstruction (transition of dilated loop and collapsed loop)
—> Mass lesion
—> Perfusion of bowel wall
—> Distant disease in case of malignancy

  1. **Sigmoidoscopy / Colonoscopy / Lower GI endoscopy
    - **
    Diagnostic
    - ***Therapeutic: Decompression in sigmoid volvulus + pseudo-obstruction, Stenting
    - Cautions: avoid excessive insufflation of gas
  2. Contrast enema (less used now)

Management (記: Resuscitation, Decompression, Surgery, Non-surgery):
1. **Resuscitation
2. **
Decompression with endoscopy
3. Operation
- ***Resection
—> Primary anastomosis
—> Without anastomosis

  • Non-resection
    —> Proximal **stoma
    —> **
    Bypass
  1. Non-surgical treatment
    - Insertion of metallic stent
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21
Q

Determinants of procedures

A

Patient factors:
1. **General condition and nutritional status
2. **
Haemodynamic status
3. ***Sepsis
4. Condition of remaining bowel

Tumour factors:
1. **Site of lesion (right colon vs left colon vs rectum)
2. **
Invasion to adjacent structures
3. ***Perforation / contamination of peritoneal cavity

Surgeon factors:
1. Experience in bowel resection and anastomosis in emergency

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22
Q

***Operative treatment of CRC

A

Right-sided obstruction: Caecum to Splenic flexure
1. Resection with Anastomosis (Ileocolic anastomosis)
- if patient stable (Right / Extended right colectomy)

  1. ***Resection without Anastomosis
    - if patient / bowel condition not favourable
  2. Non-resection: **Stoma / **Bypass
    - if advanced tumour

Left-sided obstruction:
Factors to consider:
- **Competence of IC valve (closed loop obstruction —> perforation)
- **
Heavy bacterial + faecal load in proximal colon (higher chance of infective episodes at anastomosis / surgical site)
- **Edematous unhealthy proximal colon (if unprepared)
- Poor general condition of patient:
—> malignancy + malnutrition
—> dehydration
- **
Primary anastomosis (colon to colon) is risky —> bowel compromised

  1. 3-stage operation (old fashioned, not commonly performed today):
    - Transverse colostomy —> decompression
    - Resection + Anastomosis
    - Closure of colostomy
  2. Hartmann’s operation
    - Resection without anastomosis
  3. Primary resection and anastomosis
    - Segmental resection with primary anastomosis (on table lavage to wash out faeces in proximal colon)
    - Subtotal colectomy with anastomosis of Ileum and Distal colon / Rectum

Prognosis of emergency surgery for colonic obstruction:
- Mortality >10%
- Depend on:
—> Comorbidity
—> Advanced malignancy

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23
Q

***Non-surgical treatment of CRC

A

Insertion of metallic stent
- made of metal alloys
- self-expanding mechanism
- insert + deploy under endoscopic / fluoroscopic guidance
- for definitive ***palliation (unresectable, metastatic disease)
—> avoid surgery
—> avoid stoma

  • as a bridge to surgery
    —> avoid emergency surgery
    —> ***elective operation with more time for bowel preparation
    —> more time to stage the disease
    —> lower operative mortality and morbidity
    —> reduces stoma rate
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24
Q
  1. ***Volvulus of colon
A
  • Rotation of colon along axis formed by its ***mesentery
  • Commonly at Sigmoid (65%) / Caecum (30%)
  • Colon obstruction with ***Impairment of circulation —> Prone to perforation / Ischaemia —> Surgical emergency

Investigations
- X-ray: Dilated sigmoid (**Coffee bean sign)
- Barium enema: **
Bird’s beak / Ace of spade sign

Treatment:
1. **Sigmoidoscopic decompression (successful rate: 80%, recurrence 50%)
2. **
Resection (if perforation, strangulation, failed decompression)

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3. ***Pseudo-obstruction (Ogilvie’s syndrome)
- Massive ***Colon dilatation in the absence of mechanical obstruction - Usually associated with bedridden patients with severe ***extracolonic diseases / trauma - Distended abdomen ***without pain - X-rays: Severe gaseous distension of colon Management: - Exclude mechanical obstruction 1. NG tube feeding / enemas 2. ***Colonoscopic decompression 3. ***Rectal tube decompression 4. ***Neostigmine (AChE inhibitor, cardiac SE) 5. ***Caecostomy
26
Summary
- Intestinal obstruction is a common surgical emergency - Management: Initial resuscitation —> determination of site + cause of obstruction - Decision on surgery + timing of surgery is important - High mortality if complications occur
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JC Interactive Tutorial: Intestinal obstruction
Causes: - Extramural: Adhesions, Hernia, Volvulus, Intussusception - Mural: Stricture, Malignancy - Intraluminal: Faecal impaction, Foreign body, Bezoars, Gallstones - Mechanical vs Functional Small intestine: ***Adhesion Large intestine: ***Colon cancer Cardinal signs: - Abdominal pain - Abdominal distension - Vomiting - Absolute constipation - Visible peristalsis - Focal tenderness (e.g. guarding, rebound tenderness) - Lack of abdominal tenderness (obstruction with tenderness may indicate bowel strangulation) Small intestine: - Colicky, cramping, intermittent pain - Spasms for a few minutes - Central / Mid-abdominal pain - Early vomiting (before constipation) (Gastric —> Biliary (indicate distal to Ampulla of Vater), Pancreatic —> Faeculent) —> Nature of vomitus hint level of obstruction - Late constipation Large intestine: - Longer spasm - Lower abdomen pain - Late / Less prominent vomiting - Earlier constipation - Proximal obstruction may present as small bowel IO (e.g. incompetent IC valve) Complications: - Bowel strangulation —> ischaemia - Perforation —> Pneumoperitoneum - Dehydration - Electrolyte imbalance - Pressure on diaphragm —> respiratory compromise - Vomitus aspiration Closed loop obstruction: - Surgical emergency - Second obstruction proximally (e.g. volvulus / large bowel obstruction with competent IC valve) - Strangulation —> Ischaemia —> Necrosis + Perforation Investigations: - CBC (anaemia) - LFT - RFT (U+C: hydration status) - Electrolyte imbalance —> Recurrent vomiting: Hypochloremic hypokaelmic metabolic alkalosis, Hyponatraemia —> Bowel strangulation: Metabolic acidosis, Hyperkalaemia - Arterial blood gas (Metabolic acidosis) - Venous blood gas (High lactate: ischaemia) - Amylase (leaked bowel) Imaging: - AXR (supine + erect) —> Multiple air-fluid levels —> 3, 6, 9 rule —> Pneumoperitoneum (Rigler sign) —> Thumb printing (indicate strangulation) —> Stepladder sign —> Intramural, Intraperitoneal, Extraperitoneal gas - Contrast CT General management ("Drip and suck"): - NPO (Bowel rest) - NG tube to decompress stomach - IV fluid Resuscitation —> correct electrolyte - Fecal impaction: Stool evacuation - Rigid / flexible sigmoidoscopic detorsion (for Sigmoid Volvulus) Surgical management: - Laparotomy
28
SpC Interactive tutorial: Intestinal obstruction ***Causes of of Small bowel obstruction
Classification according to Adhesion, External hernia, Virgin abdomen (∵ Management is different!!!) 1. ***Adhesion - Appendicectomy - Colorectal surgery - Cholecystectomy - Gastroduodenal surgery - Gynaecological surgery 2. ***External hernia (Give sedation —> Try reduce hernia at bedside —> Early elective surgery —> Emergency surgery) - Inguinal hernia - Femoral hernia - Incisional hernia 3. ***Virgin abdomen (Conservative management usually not successful —> Require laparotomy) ***Intraluminal: - ***Gallstone (AXR show ***pneumobilia, Treatment: Laparotomy + crushing and milk down / Enterotomy (try to avoid ∵ risk of anastomotic leak and stricture)) - Bezoars - Parasites (e.g. ascaris) - Foreign body ***Intramural: - ***Tumour —> Primary ——> Small bowel tumour (carcinoma, stromal tumour, lymphoma) ——> Carcinoma of caecum —> Secondary - ***Benign stricture —> Crohn's disease —> Radiation enteritis ***Extraluminal: - Internal hernia - Congenital adhesion - ***Intussusception (Adult usually pathological because of tumour, resection always required, pneumatic reduction unlikely useful) - ***Volvulus (Meckel's diverticulum, Malrotation)
29
Investigations of Small bowel obstruction
1. AXR - ***Dilated small bowel - ***Multiple air-fluid levels 2. CXR - ***Aspiration pneumonia - Atelectasis 3. CT scan - Dilated proximal and collapsed distal small bowel - ***May identify the cause of obstruction - ***May detect bowel ischaemia (intramural gas suggesting impending perforation)
30
Management of Small bowel obstruction
General: 1. NPO 2. ***IV fluid 3. ***NG tube decompression 4. Correction of electrolytes Adhesive obstruction: 1. ***Conservative treatment (70% usually resolve on its own) 2. ***Gastrografin meal and follow through (if no response to conservative treatment within 48 hours) 3. ***Operative treatment (if suspicion of bowel strangulation / Gastrografin shows complete obstruction - ***Enterolysis +/- ***Bowel resection External hernia: 1. ***Hernia repair 2. Bowel resection Virgin abdomen: 1. ***Laparotomy - ***Enterotomy and removal of obstructive material - ***Bowel resection - Bypass - Enterolysis - Stricturoplasty
31
***Causes of Large bowel obstruction
1. ***Colorectal carcinoma (90%) - ~10% of patients with colorectal carcinoma present with acute obstruction - CA sigmoid and descending colon (58%) - CA ascending and transverse colon (38%) - CA rectum (4%) 2. ***Volvulus - ***Sigmoid (80%) - Caecum - Transverse colon - Ileosigmoid knotting 3. ***Pseudo-obstruction 4. Diverticular disease 5. Inflammatory bowel disease 6. Irradiation stricture 7. Ischaemic stricture 8. ***Faecal impaction (Treatment: Digital evacuation)
32
Investigations of Large bowel obstruction
1. AXR - ***Distended large bowel +/- small bowel (depending on competence of ileocaecal valve) - Colonic cut off point at level of obstruction - ***Multiple air-fluid levels 2. CXR - ***Aspiration pneumonia - Atelectasis - ***Lung metastasis 3. Colonoscopy - Localization of obstructive tumour - ***Exclude synchronous tumour / polyps distal to level of obstruction - ***Stenting 4. CT - Useful if colonoscopy fails to locate obstructive tumour - ***Staging - Dilated proximal and collapsed distal large bowel - ***May identify the cause of obstruction - ***May detect bowel ischaemia (intramural gas suggesting impending perforation)
33
Management of Large bowel obstruction
1. ***Stenting - Insertion of self expanding metallic stent - Up to 22 mm diameter on full expansion - Performed under colonoscopic and fluoroscopic guidance - Avoids emergency operation and stoma - Most commonly performed for sigmoid and rectal tumours - Technically difficult for more proximal tumours 2. Surgery ***Right sided obstruction: (obstruction at ***ascending and ***transverse colon) - Right / Extended right hemicolectomy with ***primary anastomosis - Right / Extended right hemicolectomy with ***exteriorisation of bowel ends - Ileocolic bypass - Diverting stoma ***Left sided obstruction: (obstruction distal to ***splenic flexure) - 3 stage procedure - 2 stage procedure - 1 stage procedure
34
3 stage procedure
1st stage: Diverting stoma 2nd stage: Resection of tumour + Anastomosis 3rd stage: Closure of stoma   Advantage: - Treatment of choice for patients who are unfit for resection at presentation Disadvantage: - ***Decreased long term survival
35
2 stage procedure
1st stage: Resection of tumour + End colostomy (Hartmann’s operation) 2nd stage: Reanastomosis Advantage: - ***Early removal of tumour - ***Anastomosis and its attendant risk of failure are avoided in the 1st stage operation Disadvantage: - Reanastomosis can be very difficult - Up to 40% of patients did not have bowel continuity restored due to various reasons
36
1 stage procedure
1st stage: - Segmental resection (Left hemicolectomy / Sigmoid colectomy / Anterior resection) + On table irrigation + Primary anastomosis - Subtotal / Total colectomy + Primary anastomosis Advantage: - ***Avoidance of stoma Disadvantage: - Risk of anastomotic leakage 5-10%
37
Sigmoid volvulus
- Elderly - 1/3 of patients either have mental illness / institutionalised - Narrowed sigmoid mesocolon, redundant and faecal loaded sigmoid colon Treatment: 1. ***Colonoscopic decompression +/- Insertion of ***flatus tube (80% success rate) 2. ***Early sigmoid colectomy to prevent recurrence 3. ***Urgent laparotomy - peritonitis - bowel ischaemia on colonoscopy - colonoscopic decompression fails
38
Pseudo-obstruction (Ogilvie's syndrome)
- S/S of large bowel obstruction in the absence of mechanical obstruction Causes: Surgical: - pelvic surgery (15%) - trauma (11%) - orthopaedic surgery (7%) - caesarian section (4%) - cardiovascular surgery (4%) Medical: - infection (10%) - cardiac disease (10%) - neurological disease (9%) - pulmonary disease (6%) - metabolic disease (5%) - renal failure (4%) Treatment: 1. ***Colonoscopic decompression +/- Insertion of ***flatus tube 2. ***Adrenergic blocker (Guanethidine) 3. ***Parasympathomimetic agent (Neostigmine) 4. ***Caecostomy
39
SpC Interactive tutorial: Colorectal malignancy Risk factors for CRC
1. Age 2. Race 3. ***Personal history of colorectal polyps / cancer (Colonic adenoma: (SpC Medicine) - Two-thirds of all colonic polyps - Variable disease course - Risk of progression increased in advanced adenoma: —> ***High-grade dysplasia —> ***Villous histology —> ***>=1 cm —> Advanced adenoma: earlier surveillance colonoscopy) 4. ***Personal history of IBD (Crohn's, UC) 5. Type 2 DM 6. ***Family history - ***Family history without polyposis syndrome - ***FAP - ***HNPCC - Other polyposis syndrome (MYH-associated polyposis, Hamartoma polyposis) 7. Lifestyle - ***Diet —> ↑ risk: Red meat, Processed meat, Fat —> ↓ risk: Dietary fibres - ***Obesity - Alcohol - ***Smoking - Lack of exercise - Other dietary factors: Ca, Folate, NSAIDs
40
Pathogenesis of Sporadic cancer
1. ***Chromosomal instability pathway (MSS pathway) - 60-70% of sporadic cases ("classical" adenoma carcinoma sequence) - ***APC mutation (Early adenoma) —> K-ras mutation (Late adenoma) —> p53 mutation (Carcinoma) —> potential targets for Targeted therapy 2. ***Microsatellite instability pathway (MSI pathway) - 15% of sporadic cancer (not belong to HNPCC) - ***DNA mismatch repair gene mutation / silencing (Microsatellite instability) —> Mutations in regulatory genes (Carcinoma) —> potential targets for Targeted therapy Pathophysiology: - Adenoma carcinoma sequence (most common pathway) - Stepwise manner —> Polyp take ***7-10 years to progress to cancer —> Allow screening - Numerous genetic mutations involved (tumour suppression genes and oncogenes) - Invasion of the bowel wall - Spread to regional LN and distant organ by lymphatic / haematogenous / peritoneal spread
41
Site distribution of CRC
Rectum: 30% Sigmoid: 20% Left colon: 15% Transverse colon: 10% Right colon: 25% Rectum + Sigmoid + Left colon = 65% - Sigmoidoscopy: can screen up to 70% of cancer Other countries: Right shift of colon cancer (more Right colon cancer) —> sigmoidoscopy less effective as a screening tool
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Screening for CRC
Options: 1. Detect cancer - Stool for occult blood —> Guaiac based —> Faecal immunochemical test —> Stool for DNA 2. Detect cancer + polyp - Colonoscopy —> expensive + invasive —> require bowel preparation —> anaesthesia —> introduce discomfort - Sigmoidoscopy - CT / MR colonography —> can detect extra colonic lesion - Barium enema (obsolete) Recommendations for average risk persons: - After 45 years old - Colonoscopy every 10 years (if normal) - Sigmoidoscopy every 5 years —> Colonoscopy for abnormal test - CT colonography every 5 years* —> Colonoscopy for abnormal test - Barium enema every 5 years* —> Colonoscopy for abnormal test - Annual stool test (FOB or FIT)
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***Clinical features of CRC
Asymptomatic: - Detected by screening Locoregional symptoms: 1. Rectal bleeding 2. Tenesmus 3. Mucus 4. ***Change in bowel habits (Spurious / Overflow diarrhoea) 5. Abdominal pain (if cause obstruction) 6. Abdominal mass 7. Anaemia - Anaemia in elderly: suspect GI bleeding —> need to exclude CRC Systemic symptoms (Late): 1. Weight loss 2. Loss in appetite Metastatic symptoms: 1. Abdominal masses (liver, omentum) 2. Jaundice 3. Bone pain, pathological fracture (4. Lung) Acute symptoms: 1. Obstruction 2. Perforation - Localized abscess - Peritonitis 3. Severe bleeding (uncommon)
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***Investigations for CRC
1. Blood tests (workup for surgery, chemo) - Hb - LRFT 2. Tumor marker - CEA: as baseline —> ***FU of patients after curative resection —> ***Earlier detection of recurrence / metastasis —> ***Monitor treatment progress —> A glycoprotein present in primitive endoderm —> Serum level elevated usually in advanced disease —> In early disease, normal serum in 30-40% of patients —> NOT as screening / diagnosis —> Other malignant causes: gastric, pancreatic, lung cancer —> Benign causes: smoking 3. Colonoscopy - Diagnosis of tumour with biopsy (esp. important for distal rectal cancer since anal cancer will have different treatment!) - Removal of polyps - Detection of synchronous cancer 4. CT, MRI, (USG), PET scan - Extent of local disease —> Determine Surgical options, Neoadjuvant therapy - Distant metastasis
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CT, MRI, PET scan for CRC
CT: - Less accurate in assessing local diseases - Assessment of ***distant metastasis (Liver, Lung, Pelvis) MRI: Accurate in the assessing ***Rectal cancer 1. ***Mesorectal margins (distance accurately defined) —> Determine Surgical options + ***Neoadjuvant therapy + ***Prognosis of rectal cancers 2. ***Lymph nodes within and outside mesorectum (e.g. pelvic sidewall) 3. Extramural vascular invasion 4. After chemoradiation 5. For recurrent disease PET scan: - FDG is used in patients with colorectal cancer - Detects hypermetabolic lesions (both ***primary tumour, ***metastases, ***recurrences) - Helps to differentiate recurrence from scarred tissues - Helps in surgical decision in the management of recurrent / metastatic diseases
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***Staging in CRC
Purpose: 1. Guide treatment 2. Prognostication AJCC TNM staging: Stage I: ***T1-2, N0, M0 Stage II: ***T3-4, N0, M0 Stage III: any T, ***N1-2, M0 Stage IV: any T, any N, ***M1 T: - T1: invades ***submucosa (anything more superficial —> benign, other names: CIS, intraepithelial neoplasm, severe dysplasia) - T2: invades to ***muscularis propria but not through it - T3: invades through the muscularis to ***subserosa - T4 (a/b): invades ***through the serosa and to other organs N: - N0: no lymph node involved - N1: 1-3 lymph nodes - N2: 4 or more lymph nodes M: - M0: no distant metastasis - M1: distant metastasis Dukes’ staging: - Dukes’ A: tumor within the wall of the bowel - Dukes’ B: tumor invades through the wall of the bowel - Dukes’ C: presence of regional lymph node metastasis - (Dukes’ D: presence of distant metastasis)
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***Treatment for CRC
1. Surgery - ***Curative resection —> Resection of bowel segment which bears the tumor + Adequate lymphadenectomy —> Resection of distant metastasis (e.g. liver / lung metastasis) - ***Palliative resection —> Palliation of symptoms (e.g. obstruction and bleeding) (when removal of all cancer tissue not possible) - ***Non-resection —> ***Stoma / ***Bypass surgery for palliation 2. Adjuvant therapy - Depends on stage - Recommendations: —> ***Postoperative chemotherapy for Stage 3 cancer —> Regimen: 5 FU based —> New agents: Oxaliplatin, Xeloda —> Stage 2: controversial (consider if have other poor prognostic features: ***lymphovascular permeation, emergency surgery, no. of LN harvested)
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***Surgery for CRC
Principles: 1. ***Resection of the bowel segment + ***lymphadenectomy (allow pathologist for staging + prevent local recurrence) 2. Resection depends on the ***site of tumour 3. Site of resection usually determined by ***vascular anatomy (∵ lymphatics follow arteries (from Andre Tan)) 4. A mural ***margin of ***5 cm is usually adequate 5. Restoration of bowel ***continuity Emergency operation: 1. Obstruction 2. Perforation - Higher operative mortality and morbidity - Worse prognosis (stage for stage) Peri-operative preparation: 1. Mechanical bowel preparation? - mechanical prep + oral antibiotics (not GI absorbable e.g. Neomycin) 2. Prophylactic antibiotics - single dose of IV antibiotics on induction +/- 2-3 postoperative doses - prolonged antibiotics not necessary (∵ risk of Clostridium difficile) 3. Prophylactic therapy against DVT - Mechanical: Stocking - Pharmacological: Anticoagulant
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Laparoscopic colon resection
Benefits: - ***similar oncological outcome to open - less pain - shorter duration of ileus - quicker recovery - less inflammatory response - shorter hospital stay Disadvantages: - expensive instrument - longer operating time - technically more difficult
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***Complications of CRC surgery
General: 1. Cardiopulmonary 2. DVT, PE —> Early mobilisation 3. Infections —> Early feeding + remove catheter early - Wound - Pneumonia - Urinary tract - Phlebitis Acute: 1. Bleeding - ***Splenic injury - Injury to major vessels (uncommon) 2. Injury to neighbouring structures (rare now) - ***Ureter (left side cancer) - ***Duodenum (hepatic / splenic flexure) - Spleen (splenic flexure) Late: 1. ***Anastomotic leakage +/- Intra-abdominal abscess / collection - Tumour factors —> Sites of anastomosis (colon vs rectum (higher risk esp. extraperitoneal anastomosis)) —> Timing of operation (emergency (no bowel prep) vs elective) - Patient factors —> Comorbidities affect healing —> Steroid, medication affect healing - Surgeon factors —> No tension 2. ***Prolonged ileus 3. ***Intestinal obstruction (Adhesive IO)
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***Surgery for Rectal cancer
Principles: 1. Adequate ***circumferential margin (e.g. ***Total mesorectal excision —> presence of radial spread determine ***prognosis) 2. ***Narrow distal margin (2 cm) is adequate provided mesorectal dissection is performed (∵ aim to preserve anal sphincter (different from colon surgery)) 3. ***Sphincter preservation 4. ***Autonomic nerve preservation (e.g. bladder, sexual function) Treatment: 1. ***Anterior resection (aka Low anterior resection) 2. ***Abdominoperineal resection 3. ***Hartmann’s operation (resection +/- anastomosis) - Temporary (2 stage) / Permanent - Temporary: Emergency situation when a primary anastomosis is not safe - Permanent: Patients with poor sphincter function + do not want low anorectal anastomosis ∵ associated with bowel problems) 4. Local excision (for very early disease, different approaches) Preparation for rectal cancer surgery: 1. Medical consultation if necessary 2. Mechanical bowel preparation (Controversial) 3. Prophylactic IV antibiotics 4. ***Prophylaxis against DVT (∵ prolonged operation + operation in pelvis) - Mechanical: Stocking - Pharmacological: Anticoagulant 5. Consultation to enterostomal therapist and marking of stoma sites
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Determinants of sphincter preservation
Tumour factor: 1. ***Level of tumor (most important) 2. Position and fixity of tumor 3. Differentiation (poorer differentiation —> want to obtain a more distal mural margin) Patient factor: 1. Body build 2. Gender (female: wider pelvis —> easier dissection) Surgeon factor: 1. Technique and experience
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Anterior resection
- More common now than APR (∵ better anastomotic technique) - ***Resection of rectum + ***Colorectal anastomosis (連接番肛門) - Lower anterior resection: mobilisation down to distal rectum and anastomosis at the level below the peritoneal reflexion
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Abdominoperineal resection
- For ***very distal rectal cancer (***<5 cm from anal verge) - Synchronous ***abdominal + ***perineal resection - ***Permanent colostomy - Less used with better techniques in sphincter preservation
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***Complications of Rectal surgery
General: 1. Cardiopulmonary 2. DVT, PE —> Early mobilisation 3. Infections —> Early feeding + remove catheter early - Wound (***perineal wound, RT can also impair healing) - Pneumonia - Urinary tract (associated with ***urine retention) Acute: 1. Bleeding - ***Splenic injury (∵ splenic fluexure mobilisation) - Pre-sacral venous plexus 2. Injury to neighbouring structures (higher risk than Colon surgery) - Ureter - ***Urethra - ***Bladder - Spleen Late: 1. ***Anastomotic leakage +/- Intra-abdominal abscess - ***high risk ∵ distal + extraperitoneal - depends on level of anastomosis (<5% for high anterior resection, ~10% with low anterior resection) —> ***Proximal diversion by loop colostomy / loop ileostomy 2. ***Prolonged ileus 3. ***Intestinal obstruction 4. Urinary retention 5. ***Sexual dysfunction 6. ***Bowel disturbance (anterior resection: LAR syndrome) - Incontinence - Clustering of bowel movement - Urgency Stoma-related (permanent/ temporary): 1. Ischaemia 2. Retraction 3. Prolapse 4. Skin problem 5. Parastomal hernia
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Adjuvant vs Neoadjuvant therapy
Adjuvant: 1. ***Reduces local recurrence 2. ***Improves survival Options: 1. Chemo + RT Current: ***Neoadjuvant ChemoRT preferred: 1. ***Less toxicity 2. ***Downstage tumour (convert sphincter losing to sphincter saving surgery) - Regime of RT —> long course ChemoRT: 5-6 weeks (wait another 8-10 weeks for surgery for downstaging) —> short course RT: 1 week Complications: 1. Radiation cystitis 2. Radiation proctitis
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Advanced disease
Liver metastasis 1. ***Curative resection - Absence of extra hepatic disease - Location + Number of metastasis (anatomical resection not necessary) - Hepatic reserve - Synchronous vs Sequential resection with Colon surgery 2. ***Ablative therapy - RFA - Cryosurgery - Alcohol injection - Etc. 3. Palliative chemotherapy - ***Systemic (Chemotherapy, Targeted, Immunotherapy) —> Hepatic arterial infusion —> Embolisation
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Prognosis of CRC
5-year survival: Stage 1: 80-100% Stage 2: 60-80% Stage 3: 30-50% Stage 4: 10%