Small Bowel Obstruction

Question 1

What happens to bowel proximal to an obstruction

Answer 1

Becomes dilated with air and fluid

Question 2

How does an upper SBO present

Answer 2

Acute presentation
Hours of onset
Large volumes of gastric, pancreatic and biliary secretions are regurgitated into the stomach and committed as they can’t pass through the bowel

Question 3

How does a distal/large bowel obstruction present

Answer 3

Colicky abdominal pain and distension

Vomiting possible faeculent

Question 4

General symptoms of intestinal obstruction

Answer 4

Vomiting 
Pain 
Constipation 
Distension 
Complete obstruction 
Incomplete obstruction

Question 5

What determines how early vomiting developed

Answer 5

Where the obstruction is
More proximal obstructions - vomiting starts earlier

Can occur even when nothing is taken by mouth as GI secretions continue to be produced and vomited up

Question 6

Vomitus of semi-digested food eaten a day or to previously with no bile suggests what kind of obstruction

Answer 6

Gastric outlet obstruction

Question 7

Vomitus of copious amounts of bile-stained fluid suggests what kind of obstruction

Answer 7

Upper small bowel obstruction

Question 8

vomitus of thick brown, foot smelling ‘faeculent’ fluid

Answer 8

Distal bowel obstruction

Question 9

What causes the pain in intestine obstruction

Answer 9

Distension of the bowel gives intermittent episodes of colicky pain

Question 10

How does intestinal obstruction cause constipation

Answer 10

Propulsion of bowel contents stopped

bowel gas is absorbed distal to the obstruction

Question 11

What is ‘absolute constipation”

Answer 11

No faeces or gas passed

Question 12

Symptoms of large bowel obstruction developed more quickly true/false

Answer 12

False

develop more gradually due to the large capacity of the colon and caecum and their absorptive activity

Question 13

In what percentage of large bowel obstruction cases does the ileocaecal valve remain competent

Answer 13

50%
When it is competent it prevents backward flow of bowel contents

If it is incompetent the small bowel distends delaying onset of symptoms

Question 14

Why does the caecum rupture

Answer 14

Because it is thin walled and progressively distends with swallowed air

‘closed loop obstruction’

Question 15

What is incomplete obstruction

Answer 15

Bowel only partially obstructed and clinical features less defined

Vomiting intermittent and bowel habits erratic ect.

Question 16

What causes hypertrophy of the muscle of the bowel wall

Answer 16

chronic incomplete construction

Question 17

What are some physical signs of intestinal obstruction

Answer 17

Dehydration 
Abdominal distension 
Visible peristalsis 
Relative lack of abdominal tenderness 
Obstruction abdominal mass may be palpable 
Resonant percussion due to gas
Groin may have obstructing hernia

Question 18

Bowel obstruction with tenderness

Answer 18

Bowel strangulation

Question 19

What do bowel sounds sound like in intestinal obstruction

Answer 19

High-pitched and tinkling

Question 20

What investigations to do for SBO

Answer 20

Abdo x-ray - shows bowel proximal to obstruction distended with gas

CT - confirms diagnosis and look for cause

Question 21

Where do distended small bowel loops lie on AXR

Answer 21

Central

Question 22

Where does the distended large bowel sit on AXR

Answer 22

Anatomical position and has haustra coli

Question 23

What does a CT of a bowel obstruction show

Answer 23

Distended bowel proximal to obstruction and collapsed bowel distal

Question 24

Initial management of intestinal obstruction

Answer 24

Nil by mouth
Insert IV cannula and send blood
Resuscitate with IV fluids replacing electrolyte losses
Pass a nasogastric tube to decompress the stomach

Question 25

Mechanical causes of bowel obstruction

Answer 25

Adhesions or bands 
Incarcerated abdominal wall hernia 
Internal hernia 
Volvulus 
Tumour 
Inflammatory strictures 
Bolus obstruction 
Intussusception

Question 26

What causes adhesions or bands

Answer 26

congenital
previous abdominal surgery
peritonitis

(they are scarring)

Question 27

What are incarcerated abdominal wall hernias

Answer 27

inguinal 
femoral 
umbilical 
paraumbilical 
ventral 
incisional

Question 28

What is a volvulus of large or small bowel

Answer 28

Mobile loop of bowel rotates causing an obstruction at its neck

Question 29

What causes inflammatory strictures which cause obstruction

Answer 29

Crohn’s disease
Diverticular disease

Inflam causing narrowing of the bowel

Question 30

What kind of bolus can cause obstruction

Answer 30

Food bolus
Impacted faeces
impacted gallstone ileus
trichobezoar (ingestion of hair)

Question 31

What is intussusception

Answer 31

A segment of bowel wall becomes folds into the segment distant to it

eg. small intestine inside the large intestine and ileocaecal valve

Question 32

What is bowel strangulation

Answer 32

Segment of bowel becomes trapped so that its lumen becomes obstructed and its blood supply compromised

Question 33

What is Adynamic bowel obstruction

Answer 33

failure of peristalsis

Question 34

Risk factors for adynamic bowel obstruction

Answer 34

Recent GI surgery
Inflammation with peritonitis
Diabetic keto acidosis

Question 35

Types of adynamic bowel obstruction

Answer 35

Paralytic ileus

Pseudo obstruction

Question 36

Treatment for adynamic bowel obstruction

Answer 36

‘Drip and suck’ while awaiting restoration of peristalsis

Question 37

What is pseudo obstruction

Answer 37

acute dilation of the colon in the absence of colonic obstruction in acutely unwell patients