Intestinal obstruction

Question 1

What is intestinal obstruction?

Answer 1

Obstruction of normal movement of bowel contents: mechanical blockage

Question 2

How may intestinal obstruction be classified?

Answer 2

Small or Large bowel
Partial or Complete obstruction
Simple or Strangulated
Extramural, intramural or intraluminal

Question 3

List 4 causes of extramural intestinal obstruction

Answer 3

Hernia (SB)
Adhesions (SB)
Bands
Volvulus (LB)

Question 4

List 4 causes of intramural intestinal obstruction

Answer 4

Tumours: Single or Multifocal (LB)
Inflammatory strictures (e.g. Crohn’s)
Diverticular strictures (LB)
Intussusception

Question 5

List 3 causes of intraluminal intestinal obstruction

Answer 5

Pedunculated tumours
Foreign body (e.g. bezoars, gallstones)
Faecal impaction

Question 6

Describe the epidemiology of intestinal obstruction

Answer 6

COMMON

More common in ELDERLY due to increased incidence of adhesions, hernias + malignancy

Question 7

List 5 symptoms of intestinal obstruction

Answer 7

Severe gripping colicky pain with periods of ease
Abdo distension
Vomiting (may be bile-stained or faeculent)
Absolute constipation
Anorexia

Question 8

Describe pain in small bowel obstruction

Answer 8

Colicky (cramping + intermittent), with spasms lasting a few minutes.
Pain central + mid-abdominal.
Vomiting may occur before constipation

Question 9

Describe pain in large bowel obstruction

Answer 9

felt lower in the abdomen + spasms last longer.

Question 10

List 5 signs of intestinal obstruction

Answer 10

Abdo distension with generalised tenderness
Visible peristalsis
Tinkling bowel sounds
Tympanic to percussion
Peritonitis: absent bowel sounds, guarding + rebound tenderness

Question 11

List 4 investigations used for intestinal obstruction

Answer 11

Bloods
ABG/ VBG (High lactate indicates poor bowel perfusion)
AXR: Assists dx + localisation
CT: establishes cause

Question 12

What may be seen on abdominal x-ray in small bowel obstruction?

Answer 12

dilated bowel >3cm
Central gas shadows
Valvulae conniventes (completely cross the lumen)
No gas in large bowel

Question 13

What may be seen on abdominal x-ray in large bowel obstruction?

Answer 13

Dilated bowel >6cm or >9cm if at caecum
Peripheral gas shadows proximal to the blockage
Haustra which don’t cross whole lumen width

Question 14

What may FBC show in intestinal obstruction?

Answer 14

Increased WBC (inflammation)
Anaemia (if Ca)

Question 15

Describe general management of intestinal obstruction

Answer 15

Drip + suck: NGT (decompress) + IV fluids to rehydrate + correct electrolyte imbalance
Analgesia
Urinary catheter + monitor fluid balance

Question 16

In which cases is surgical management considered for intestinal obstruction?

Answer 16

Strangulation
Closed loop obstruction
Obstructing tumour
If not improved with conservative management after 48 hrs
If perforation or peritonitis suspected

Question 17

List 4 complications of intestinal obstruction

Answer 17

Dehydration
Bowel perforation leading to Peritonitis
Toxaemia (blood poisoning)
Gangrene of ischaemic bowel wall

Question 18

What is the prognosis for intestinal obstruction?

Answer 18

Variable

Dependent on the general state of the patient + prevalence of complications

Question 19

How does Gallstone Ileus occur?

Answer 19

When a stone erodes through the gallbladder into the duodenum, forming a cholecysto-duodenal fistula
= mechanical obstruction caused by an impacted gallstone in the small bowel

Question 20

Which obstructions can be managed conservatively (at least initially)?

Answer 20

Ileus

Incomplete small bowel obstruction

Question 21

What surgery is required in in acute obstruction?

Answer 21

Emergency laparotomy

Question 22

What should you look out for when suspecting intestinal obstruction?

Answer 22

Hernias 
Abdo scars: previous abdo surgery increases risk of adhesions 
Abdo mass (e.g. intussusception, carcinoma)

Question 23

What bloods should be taken in suspected intestinal obstruction?

Answer 23

FBC
CRP: HIGH
U+E's: deranged due to vomiting
Glucose (Exclude DKA)
G+S

Question 24

What is it important to monitor in patients with intestinal obstruction?

Answer 24

Electrolyte changes

3rd space losses (causes dehydration)

Question 25

What may cause a metabolic alkalosis in intestinal obstruction?

Answer 25

Hypokalaemia due to vomiting

Sequestration of fluid in distended bowel loops (3rd spacing) causing dehydration

Question 26

What may cause a metabolic acidosis in intestinal obstruction?

Answer 26

Anaerobic metabolism by ischaemic cells producing lactic acid
Lysis of ischaemic cells releasing intracellular K+

Question 27

What is Ileus?

Answer 27

Slowing of GI motility + distention, with no mechanical intestinal obstruction