Bowel obstruction

Question 1

What is more common, small or large bowel obstruction?

Answer 1

Small bowel obstruction

Question 2

Why does bowel obstruction cause fluid losses?

Answer 2

Fluid is secreted by the bowel that is then usually absorbed in the distal colon. When this reabsorption cannot occur, this leads to fluid losses from the intravascular space into the GI tract. This is known as “third spacing”

Question 3

3 biggest causes for bowel obstruction?

Answer 3

“TAH”

Tumours
Adhesions
Hernias

Other causes include volvulus, diverticular disease, strictures and intussusception (paeds 6 months-2 years)

Question 4

What are adhesions?

Answer 4

Scar tissue that bind abdominal contents together.

This causes kinking and squeezing of the bowel. Often more common in small bowel.

Question 5

What are the causes of adhesions?

Answer 5

Abdomino-pelvic surgery - more often open
Peritonitis
Abdominal/pelvic infections
Endometriosis 
Congenital 
Iatrogenic - radiotherapy

Question 6

What is it called when there are two points of obstruction in a bowel causing a middle section between the two?

Answer 6

Closed loop bowel obstruction.

Question 7

What causes a closed loop obstruction?

Answer 7

Hernias

Adhesions

Volvulus

Single point of obstruction in the large bowel and a competent ileocaecal valve.

Question 8

Complications of closed loop bowel obstruction?

Answer 8

Ischaemia and perforation.

Requires emergency surgery.

Question 9

Clinical presentation of bowel obstruction?

Answer 9

Vomiting - green and bilious 
Abdominal distension
Diffuse abdo pain
Constipation
Lack of flatulence 
Bowel sounds - tinkling

Question 10

What is the key finding of bowel obstruction in AXR?

Answer 10

Distended loops of bowel

Question 11

What are the upper limits of the normal diameter of small bowel, colon and caecum?

Answer 11

Small bowel 3cm

Colon 6cm

Caecum 9cm

Question 12

What is the name for the mucosal folds that form lines extending the full width of the bowel?

Answer 12

Plicae circulares OR Valvulae conniventes

Question 13

What is the name for the pouches formed by the muscles in the walls of the bowel, which form lines that do not extend the full width of the bowel on an abdominal x-ray?

Answer 13

Haustra, found in the large bowel.

Question 14

What does a raised serum lactate suggest in a patient with bowel obstruction?

Answer 14

Bowel ischaemia

Question 15

What is the name of the condition affecting the small bowel, where the normal peristalsis that pushes the contents along the length of the intestines, temporarily stops?

Answer 15

Ileus

Question 16

When are you most likely to find a patient with ileus?

Answer 16

Post operatively or with electrolyte imbalance

Question 17

What are the two types of volvulus and which type is more common?

Answer 17

Caecal and sigmoid. Sigmoid is more common.

Question 18

What might you find on investigative bloods in bowel obstruction?

Answer 18

Electrolyte imbalances
Metabolic alkalosis - due to excessive vomiting
Raised lactate

Question 19

What is the initial management for bowel obstruction?

Answer 19

Drip and suck

IV fluids to hydrate the patient and correct electrolyte imbalances

NG tube

Question 20

First line investigation for bowel obstruction?

Answer 20

Abdominal x-ray is initial investigation however if patient is presenting acutely CT scan is usually carried out.

Erect CXR used to demonstrate abdominal perforation

Question 21

Gold standard diagnostic investigation for bowel obstruction?

Answer 21

Contrast abdominal CT scan is usually required to confirm the diagnosis and establish the site and cause.

Can also be used to diagnose intra-abdominal perforation

Question 22

Management of sigmoid volvulus?

Answer 22

Conservative management initially - if sigmoid volvulus does not self resolve within 48 hours, then:

• Sigmoidoscopy to locate correct area of twisted bowel
• Flatus tube inserted to relieve compression (left in situ for up to 24 hours)

Question 23

When is surgery indicated in a sigmoid volvulus?

Answer 23

• Advanced volvulus - ischaemic/necrotic

* Repeated failed attempts at decompression

Question 24

What surgical intervention is carried out if required in volvulus?

Answer 24

A laparotomy for Hartmann’s procedure (necrotic sigmoid bowel removed and end colostomy formed)

Question 25

Management of a caecal volvulus?

Answer 25

Cecopexy - surgical manipulation to place the caecum back into rightful position

Definitive management is laparotomy with ileocaecal resection or right hemicolectomy.

Question 26

What is the mesentery?

Answer 26

The mesentery is the membranous peritoneal tissue that creates a connection between the bowel and the posterior abdominal wall.

Question 27

What are the key risk factors for a sigmoid volvulus?

Answer 27

Chronic constipation

Lengthening of the mesentery that is attached to the sigmoid colon.

High fibre diet

Pregnancy

Adhesions