Bowel obstruction

Question 1

What happens to bowel proximal to obstruction?

Answer 1

Dilation even if not eating. Can be with with gas or food or fluid (gastric secretions)

Question 2

What happens to bowel distal to obstruction?

Answer 2

Collapse

Question 3

How does an upper small bowel obstruction present?

Answer 3

Acute onset (hours) 
Large volumes of vomit.
Vomiting bile if obstruction distal to ampulla of Vater

Question 4

How does a distal small bowel or large bowel obstruction present?

Answer 4

Colicky abdominal pain due to bowel peristalsing. Smooth muscle- visceral pain.
Vomiting, possiblely faeculent.
Gradual onset

Question 5

General symptoms of intestinal obstruction?

Answer 5

Vomiting, pain, constipation, distention.

Question 6

WHat does vomit of semi-digested food eaten in the last 24-48 hours with no bile sugegst?

Answer 6

Gastric outlet obstruction

Question 7

What does vomit which is bile stained suggest?

Answer 7

Proximal half of small bowel

Question 8

What does vomit that is thicker, brown, foul smelling vomit suggest?

Answer 8

A more distal obstruction of small bowel or colon

Question 9

What is absolute constipation?

Answer 9

Neither faeces or flatus passed rectally.

Pathognenomic of bowel obstruction

Question 10

What is meant by a competent ileo-caecal valve?

Answer 10

Backwars flow of accumulated bowel contents is prevented.
Distention of colon but not small bowel (greater risk of perforation-caecum is thin walled)
50% of patients

Question 11

What is meant by an incompetent ileo-caecal valve?

Answer 11

The ileo-caecal valve allows backwards movement of colic contents.
Distention of small and large bowel.
50% of patients.
Delays onset of symptoms

Question 12

What are the symptoms of incompete or sub total obstruction?

Answer 12

Intermittent vomiting and bowel movements.
Severe pain in chronic incomplete obstruction is more common because smooth muscle proximal undergoes hypertrophy and contracts harder to force contents past obstruction.

Question 13

What are the physical signs of intestinal obstruction?

Answer 13

Dehydration (dry mouth, loss of skin turgor and elasticity)
Abdominal distention
Visible peristalsis (thin patients and chronic incomplete obstruction)
Lack of abdominal tenderness- should not be peritonitic)
Palpable mass
Resonant percussion due to gas in bowel
Check groins for hernia
Tinkling or absent bowel sounds or echoing (lots of fluid)

Question 14

What do you worry about if the patient is peritonitic?

Answer 14

Bowel strangulation or perforation.

Question 15

What are the investigations for bowel obstruction?

Answer 15

Suprine AXR- proximal distention of bowel with gas. You can also see competent or incompetent ileo-caecal valve. (Erect AXR will show air fluid lines- not comon practice)
Erect CXR- free gas under the diaphragm
CT scan looking for transition point (distention proximal to obstruction and collapse distal)

Question 16

How is intestinal obstruction managed?

Answer 16

Nil by mouth
Bloods
Insert canula- Give IV fluids and correct elecrolytes.
NG tube to decompress stomach
DRIP AND SUCK for 48-72 hours and reveiw

Question 17

What are the causes of bowel obstruction?

Answer 17

Adhesions/bands (can be congenital but often from surgery)
Incarcerated hernia
Volvulus
Tumour
Inflammatory strictures
Bolus obstruction
Intussusception

Question 18

What are the common hernia sites?

Answer 18

Epigastric
Umbilical/paraumbilical
Incisional
Spiegel (side of rectus sheath)
Inguinal
Femoral

Question 19

Which hernias are difficult to see?

Answer 19

Femoral hernias- may only be seen on CT

Question 20

Most common site of volvulus?

Answer 20

1) Sigmoid colon

Also caecum and small bowel rarely

Question 21

Which patients get volvulus’?

Answer 21

Older patients with long term difficulties with constipation

Question 22

How is a volvus treated?

Answer 22

Ridgid sigmoidoscopy or flexible colonoscopy

Question 23

What are the most common obstructing tumours?

Answer 23

Colorectal cancer

Question 24

What size is the caecum when at risk of perforation?

Answer 24

> 10cm worrying

>16cm is very likely to perforate => peritonitis

Question 25

What can cause inflammatory strictures leading to bowel obstruction?

Answer 25

Chron’s disease (distal ileum)
Divericular disease
Usually incomplete obstruction.

Question 26

What are the bolus obstructions in the GI tract and where are they commonly found?

Answer 26

Food bolus- distal oesophagus (stricture form cancer or reflux oesophagitis)
Impacted faeces- older people, dehydration
gallstone ileus- ileocaecal valve. (Due to fistula between gall bladder and duodenum)
Trichobezoar hair(rare)

Question 27

What is intussesception?

Answer 27

A segment of bowel wall becomes telescoped into the segment distal to it.
Common in children.
Due to a mass in the bowel wall: enlargement of lymphatic tissue or tumour.

Question 28

What are they symptoms of bowel strangulation?

Answer 28

Severe ischemic pain

Question 29

WHat is the pathophysiology of bowel strangulation?

Answer 29

A segment of bowel becomes trapped.
Venous return obstructed 
Intravascular pressure rises and then arterial flow is compromised 
=> ischemia, infarction and perforation.
Occurs in external hernia or volvus.

Question 30

What is the abdominal venous pressure?

Answer 30

14mmHg

Question 31

What is paralytic ileus, when does it occur and how is it treated?

Answer 31

Occurs following surgery or inflammation with peritonitis and usually effects the small intestine.
Failure of peristalsis. Less pain and bowel sounds
Generally just wait for bowel to settle. Can try drip and suck for fluid

Question 32

What is adynamic bowel obstruction?

Answer 32

Its not mechanical obstruction but its paralysed. Gas and fluid is not moving- no peristalsis.

Question 33

What is pseudo obstruction?

Answer 33

Acute dialition of the colon in the absence of colonic obstruction in acutely unwell patients.

Question 34

What are the risk factors for pseudo obstruction?

Answer 34

Elderly
Hip replacement surgery
CABG
Spinal fracture
Pneumonia

Question 35

How is pseudo obstruction treated?

Answer 35

Most resolve spontaneously.

If symptomatic and effecting diaphragm or threatening colon- decompression with colonoscope