Bowel Obstruction

Question 1

What is Bowel Obstruction?

Answer 1

A surgical emergency - blockage to the passage of foods, fluid and gas through the intestines.

Question 2

Which type of Bowel Obstruction is commoner?

Answer 2

Small Bowel > Large Bowel.

Question 3

Vomiting in Bowel Obstruction (2).

Answer 3

1. Build-up of gas and faecal matter proximal to obstruction.
2. Back-pressure = vomiting and dilation of intestines proximal to obstruction.

Question 4

Why is Bowel Obstruction a Surgical Emergency? (4)

Answer 4

1. GI Tract secretes fluid which is resorbed in the colon.
2. Obstruction = fluid does not reach colon.
3. Fluid Loss from Intravascular Space into GI Tract (3rd Spacing) = Hypovolaemia and Shock.
4. When obstruction is higher up in the intestines, fluid losses are greater.

Question 5

Aetiology of Bowel Obstruction (7).

Answer 5

90%
1. Adhesions (Small Bowel).
2. Hernias (Small Bowel).
3. Malignancy (Large Bowel).
Rest :
A. Volvulus (Large Bowel).
B. Diverticular Disease.
C. Strictures (Crohn’s).
D. Intussusception.

Question 6

What are Adhesions?

Answer 6

Pieces of scar tissue that bind the abdominal contents together, causing kinking/squeezing of the bowel.

Question 7

Aetiology of Intestinal Adhesions (4).

Answer 7

1. Abdominal/Pelvic Surgery.
2. Peritonitis.
3. Abdominal/Pelvic Infections.
4. Endometriosis.

Question 8

What is a Closed Loop Obstruction?

Answer 8

Two points of obstruction along the bowel with an obstruction-free area in between.

Question 9

Aetiology of Closed Loop Obstruction (4).

Answer 9

1. Adhesions that Compress 2 Areas of Bowel.
2. Hernias that Isolate a Section of Bowel Blocking Either End.
3. Volvulus where the Twist Isolates a Section of Intestine.
4. Single Obstruction with a Competent Ileocaecal Valve.

Question 10

What is a Competent Ileocaecal Valve?

Answer 10

A valve that prevents movement back into the ileum from the caecum.

Question 11

Clinical Presentation of Bowel Obstruction (5).

Answer 11

1. Vomiting - Green Bilious.
2. Abdominal Distension.
3. Diffuse Abdominal Pain.
4. Absolute Constipation & Lack of Flatulence.
5. Tinkling Bowel Sounds (Early).

Question 12

Imaging in Bowel Obstruction (3).

Answer 12

1. X-Ray : Distended Loops of Bowel.
2. Upper Limits of Normal Diameter = 3cm for Small Bowel; 6cm for Colon; 9cm for Caecum.
3. X-Ray : Valvular Conniventes.

Question 13

What are Valvular Conniventes?

Answer 13

Mucosal folds that form lines extending the full width of the bowel.

Question 14

Differences Between Valvular Conniventes (2).

Answer 14

1. VC = Small; Haustra = Large.
2. VC = Full Width; Haustra = Partial.

Question 15

Management of Bowel Obstruction (4).

Answer 15

1. A-E Approach.
2. Initial - Drip and Suck.
3. Conservative - if Adhesions/Volvulus.
4. Definitive - Surgery.

Question 16

Drip and Suck Management (3).

Answer 16

1. NBM.
2. IV Fluids to Hydrate and Correct Electrolyte Imbalances.
3. NG Tube with Free Drainage - Allow stomach contents to freely drain and reduce risk of vomiting and aspiration.

Question 17

Investigations in Bowel Obstruction (4).

Answer 17

1. Bloods - U&Es : Electrolyte Imbalances.
2. VBG - Metabolic Alkalosis (Vomiting).
3. VBG - Raised Lactate (Bowel Ischaemia).
4. Imaging - 1st AXR; Contrast Abdominal CT (Confirm diagnosis and Establish Site/Cause); Erect CXR for Perforation.

Question 18

Surgical Management of Obstruction (4).

Answer 18

1. Exploratory Surgery (Unclear Cause).
2. Adhesiolysis.
3. Hernia Repair.
4. Emergency Resection (Tumour).

Question 19

Complications of Obstruction (4).

Answer 19

1. Hypovolaemic Shock (3rd Spacing).
2. Bowel Ischaemia.
3. Bowel Perforation.
4. Sepsis.