Bowel Obstruction.

Question 1

What happens to the bowel proximal to a bowel obstruction?

Answer 1

It becomes dilated with air, gas, and fluid.

Question 2

What happens to peristalsis during a bowel obstruction?

Answer 2

It is disrupted.

Question 3

What does the bowel obstruction patients presentation depend on?

Answer 3

Dependent on the level of obstruction.

Question 4

How does an upper small bowel obstruction present?

Answer 4

Acute onset within the last few hours.

Vomiting large volumes of gastric, biliary, salivary and pancreatic secretions.

Question 5

Where do bowel obstructions occur?

Answer 5

Any part of the bowel.

Question 6

How does an obstruction of the distal small or large bowel present?

Answer 6

Colicky abdominal pain and distension.

Vomiting, possibly feculent.

Question 7

What does the onset of vomiting tell us about the location of a small bowel obstruction?

Answer 7

The quicker is starts the more proximal the blockage is.

Question 8

What are the general symptoms of bowel obstruction?

Answer 8

Vomiting, pain, constipation and distension.

Question 9

Can vomiting be present in bowel obstruction without any food intake?

Answer 9

Yes can occur with biliary and gastric secretions and saliva.

Question 10

What kind of vomit does a gastric outlet obstruction present with?

Answer 10

Semi digested, eaten a day or two prior without any bile present.

Question 11

What kind of vomit do we get with a small bowel obstruction?

Answer 11

Copious bile stained fluid.

Question 12

What kind of vomit do we get with a distal obstruction?

Answer 12

Thicker, brown, feculent, foul smelling vomit.

Question 13

What causes the pain from a bowel obstruction?

Answer 13

Distension of the proximal gut by air and secretions.

Colicky pain in attempt to clear the blockage.

Question 14

What is complete cessation of flatus and faeces indicative of and why?

Answer 14

Complete bowel obstruction.

Propulsion of contents is arrested and the gas is absorbed in the distal part of the bowel.

Question 15

How quick an onset of symptoms do we get with a large bowel obstruction and why?

Answer 15

More gradual development due to colon and cecum absorptive capacity.

Question 16

What happens to the ileocecal valve in 50% of cases and what consequences does this have?

Answer 16

Remains competent half the time preventing backward flow. The thin walled cecum progressively dilates with swallowed air and may rupture (closed loop obstruction).
If the valve is incompetent, the small bowel dis tends and delays the onset of symptoms.

Question 17

What symptoms do we get during an incomplete obstruction?

Answer 17

The clinical features are less defined. The vomiting may be intermittent and the bowel habits erratic.

Question 18

What happens to the bowel when there is a chronic incomplete obstruction?

Answer 18

Leads to gradual hypertrophy of the smooth muscle of the bowel wall proximally. Peristaltic activity in the hypertrophic muscle is responsible for bouts of colicky pain. These can be more prominent than in complete obstruction.

Question 19

What are the signs of obstruction?

Answer 19

Dehydration, abdominal distension, visible peristalsis and a relative lack of tenderness. Possibly a palpable mass, altered percussion notes and bowel sounds.

Question 20

What anatomical area must we make sure we examine when a patient has a suspected obstruction and why?

Answer 20

The groin for an obstructing hernia.

Question 21

What are the signs of dehydration?

Answer 21

Dry mouth, loss of skin turgor and elasticity.

Question 22

What should we think if the patient is tender and has signs of a bowel obstruction?

Answer 22

May indicate an obstruction due to strangulation.

Question 23

What can we often hear on abdominal percussion in a bowel obstruction?

Answer 23

Centre of abdomen tends to be resonant due to gassy distension.

Question 24

What bowel sounds do we hear with a bowel obstruction?

Answer 24

Traditionally a high pitched tinkling.

In reality can be absent, echoing cavernous sounds or may sound like water lapping against a boat.

Question 25

What investigations do we do for a bowel obstruction?

Answer 25

Supine xray most useful. Erect no longer done.

Question 26

What do we see on an abdominal xray in a bowel obstruction?

Answer 26

The bowel proximal is distended with gas.
Distended small bowel loops tend to be central and have valvulae conniventes.
Distended large bowel stays in the anatomical position and have Haustra coli.
A Cut off will be seen between the distended proximal bowel and the collapsed distal bowel.

Question 27

What are valvulae conniventes?

Answer 27

Otherwise called the plicae conniventes. The lines of smooth muscle straight across the bowel.

Question 28

What is the management of a bowel obstruction?

Answer 28

NG tube to decompress the stomach, nil by mouth, cannula and bloods, resus with fluid and electrolytes and a surgical consult if pain.

Question 29

What are mechanical causes of a bowel obstruction?

Answer 29

Adhesions or bands.
Incarcerated or internal hernias.
Volvulus.
Tumour.
Inflammatory strictures.
Bolus obstruction.
Intussusception..

Question 30

What can cause adhesions of bands?

Answer 30

Congenital or resulting from past surgery or peritonitis.

Question 31

What hernias can incarcerate?

Answer 31

Inguinal, femoral, umbilical, paraumbilical, ventral and incisional.

Question 32

What is a volvulus?

Answer 32

Mobile bowel of loop that rotates causing obstruction at its neck.

Question 33

What tumours can cause bowel obstruction?

Answer 33

Gastric cancer blocking the pylorus.

Small bowel tumours which are rare and large bowel cancer.

Question 34

What causes inflammatory strictures and what can this result in?

Answer 34

Diseases like diverticular or Crohn’s.

Usually result in incomplete obstruction.

Question 35

What kind of bolus can cause obstruction?

Answer 35

Food, faeces, impacted gallstone ileus (rare) and trichobezoar (rare).

Question 36

What is a trichobezoar?

Answer 36

A hairball.

Question 37

What is Intussusception?

Answer 37

Segment of bowel wall becomes telescoped into the segment distal to it.

Question 38

What causes an Intussusception and what patients are the more common in?

Answer 38

Usually initiated by a mass in the bowel wall, enlargement of lymphatic tissue or tumour.
More common in children.

Question 39

What happens in bowel strangulation?

Answer 39

Segment becomes trapped and if not relieved will progress to infarction and perforation. Lumen becomes obstructed (incarcerated) and then the blood supply is compromised (strangulated).

Question 40

What can cause pain over a hernia and what actions should we take?

Answer 40

Can occur in external hernia or volvulus and this needs rapid surgical evaluation.

Question 41

What are the causes of a dynamic bowel obstruction?

Answer 41

Paralytic ileus and pseudo obstruction.

Question 42

What is a pseudo obstruction?

Answer 42

Inability of bowel to push food properly.

Question 43

What is paralytic ileus?

Answer 43

Obstruction of the intestine due to paralysis of the intestinal muscles. Does not need to be complete paralysis just enough to stop the contents from passing through.
Otherwise just called ileus.