Bowel Obstruction

Question 1

Define bowel obstruction

Answer 1

Blockage (partial or complete) of bowel which blocks passage of intestinal content

Question 2

How are BO generally classified?

Answer 2

• Mechanical
  
  • SBO
    
    • Adhesions, hernia, malignancy, Intussusception
  • LBO
    
    • Colorectal ca, Volvulus, Diverticular stricture
• Non mechanical - failure of peristalsis to occur
  
  • Paralytic ileus
  • Acute-colonic Pseudoobstruction (oglive syndrome)

Question 3

Deescribe the patho[physiology of bowel obstruction (BO)

Answer 3

1. Bowel segment becomes occluyded
2. P{roximal limb dilates
3. Inc peristalsis of bowel
4. Inc secretion of electrolyte rich fluid

Question 4

What is a closed loop obstruction?

Answer 4

• Bowel obstructed @ two points

Question 5

Examples of closed loop obstruction?

Answer 5

• volvulus
• large bowel obstruction c competent ileocaecal valve

Question 6

What are the causes of BO?

Answer 6

SBO

• post operative adhesions (most common)
• hernia
• Intussusception, Gallstone ileus, IBD, malignancy

LBO

• malignancy (most comon)
• diverticular disease (second common)
• volvulus

Question 7

Mechanical BO can be classified into intraluminal, mural and extramural. What are they?

Answer 7

Intraluminal

• fecal
• foreign body
• gallstone ileus

Mural

• cancer
• strictures
• diverticulum
• intussusception

Extramural

• hernias
• adhesions
• volvulus

Question 8

What are the cardinal signs of BO?

Answer 8

• Abdominal pain - colicky
• Vomiting (early in SBO)
• Obstipation (early in LBO) - cannot pass stool and gas
• Abdominal distentiion

Question 9

What will you find on Ex wth BO?

Answer 9

• Palpate: peritonism signs
  
  • localised tenderness
  • Guarding
  • Rebound tenderness
• Auscultate: tinkling/absent bowel sounds

Question 10

What are your differentials for BO?

Answer 10

• pseudo-obstruction
• ileus
• toxic megacolon
• constipation

Question 11

What are the types of BO

Answer 11

Simple

• 1 obstructing point, no vascular compromise

Closed loop

• 2 obstructing points

STrangulated

• vascular compromise
• localised pain
• peritonism
• fever and WCC

Question 14

What are the non mechanical causes of BO?

Answer 14

• ileus
• peritonitis
• pancreatitis
• low potassium
• mesenteric ischaemia

Question 15

What Ix would you order for BO?

Answer 15

Bedside

• Observations
• ECG
• Fluid balance
• PR examination
• Pregnancy test

Bloods

• routine
• VBG/ABG - lactate
• G+S

Imaging

• CXR - check for pneumoperitoneum
• AXR - signs of dilation
• CT abdo-pelvis

Special test

• Gastrograffin - look for mechanical ob
• Colonoscopy - High risk of perforation

Question 16

What will you look for on AXR for BO?

Answer 16

• Small bowel
  
  • Valvulae conniventes
• Large bowel
  
  • Haustral folds
• 3,6,9 rule
• Sigmoid volvulus
  
  • from LUQ to RUQ
  • coffee bean signs
  • No haustral lines
• Caecal volvulus
  
  • from RLQ to E/LUQ
  • Haustral lines

Question 17

Why is CT preferred over AXR for BO?

Answer 17

• more sensitive for BO
• can differentiate between mechanical and pseudoobstruction
• Can demonstrate site and cause
• can demonstrate presence of mets

Question 18

What scoring system is used to estimate morbidity and mortality in gen surg patients undergoing surgical management?

Answer 18

• P-POSSUM

Question 19

What are the advantages of gastrograffin for SBO?

Answer 19

• non irritating to gut
• act as osmotic agent, decreaseing oedema in gut
• inc. bowel motility

Question 20

What are the initial mx of BO?

Answer 20

• Fluid resus
• Urine catheter
• If ischaemic - urgent surgery

Question 21

What are the mx for BO?

Answer 21

Conservative (drip and suck)

• NBM
• Nasogastric decompression
• Analgesia
• O2
• Anti emetics
• Fluid resus, correct electrolyte
• UC & Fluid balance
• Abx as needed

Surgical

• Decompress obstructed bowel
• SBO
  
  • resection + primary anastomose
  • resection with defunctioning stoma
  • adhesiolysis - adhesions
  • • LBO
  • defunctioning stoma and resection with primary anastomosis.
  • endoscopic stenting
  • Flatus tube

Question 22

What are the features which indicate risk of strangulation in bowel obstruction?

Answer 22

• tachycardia
• fever
• tenderness + peritonism
• high leukocytes
• incarcerated hernias or unscarred abdomen

*strangulation or ischaemic bowel is a surgical emergency

Question 23

What are the indicators for surgery in bowel obstruction?

Answer 23

• mechanical obstruction with no previous surgery
• signs of strangulation
• complete obstruction on gastrgrafin flow
• no possibility of colonic stenting

Question 24

How would you manae paralytic ileus?

Answer 24

• electrolyte abnormality corrected
• IVF administered
• NG tube decompression
• opiate analgesia

Question 25

How would you tx Acute colonic pseudo-obstruction?

Answer 25

• Neostigmine (cholinesterase inhibitor) given to encourage motility
• Endoscopic colonic decompression in those failing to respond.
• Surgery

Question 26

What are the Cx for bowel obstruction?

Answer 26

• ISchaemia
• Perforation
• Dehydration - AKI