Small bowel obstruction

Question 1

Define a small bowel obstruction.

Answer 1

· A mechanical disruption in the patency of the GI tract.

Question 2

Having which disease increases the incidence risk of a small bowel obstruction?

Answer 2

Crohn’s disease.

Question 3

What is the pathophysiology of a small bowel obstruction?

Answer 3

· Interruption in the patency of the GI tract.
· Proximal dilation of the intestine, with peristalsis, leads to abdominal cramping (colic), which can become severe.
· This may be accompanied by vomiting.
· The distal interruption of faecal flow leads to absolute constipation.
· In acute cases, there may be hyperperistalsis distal to the obstruction, leading to diarrhoea.
· Over time, obstructed bowel will prevent venous drainage with the possible result of decreased arterial perfusion.

Question 4

Untreated patients can develop what 3 things?

Answer 4

1. Progressive intestinal ischaemia.
2. Necrosis.
3. Perforation.

Question 5

What 3 type of mechanical obstructions can cause a small bowel obstruction?

Answer 5

1. Simple = 1 point
2. Closed Loop (volvulus)
3. Strangulated (blood supply compromised and patient more ill than you expect).

Question 6

What is the prognosis of a small bowel obstruction?

Answer 6

· Patients treated in a timely manner have a very good prognosis.
· In untreated patients, obstruction progresses to necrosis, perforation, sepsis and multi-organ failure.

Question 7

What is the aetiology for a small bowel obstruction?

Answer 7

Adults:

• Previous surgery with formation of adhesions.
• Inguinal hernia incarceration, ventral, incisional, umbilical and parastomal hernias.
• Crohn’s disease.
• Intestinal malignancy.
• Appendicitis.

Children:

• Appendicitis.
• Intussusception.
• Intestinal atresia.
• Volvulus.

Question 8

Small bowel obstructions are classified into which 2 catergories?

Answer 8

1. Partial (incomplete) bowel obstruction:
   - Blockage is not complete, resulting in partial passage of flatus and occasional stool.
   - Not a surgical emergency and may resolve non-operatively.
2. Complete bowel obstruction:
   - Emergency.
   - Intestinal lumen completely obstructed.
   - Failure to pass flatus or stool.
   - Generally associated with peritonitis.

Question 9

What risk factors can cause a small bowel obstruction?

Answer 9

· Previous abdominal surgery - due to adhesions. 
· Malrotation. 
· Crohn's disease. 
· Hernia. 
· Appendicitis. 
· Intestinal malignancy. 
· Intussusception.
· Volvulus. 
· Intestinal atresia.
· Foreign body ingestion.

Question 10

What are the common signs and symptoms of a small bowel obstruction?

Answer 10

· Failure to pass flatus or stool.
· Abdominal pain. Crampy and intermittent, can be severe.
· Vomiting. May be bilious, occurs after the pain.
· Abdominal distension. High-pitched, increased frequency bowel sounds.
· Abdominal tenderness.
· Peritonitis. In the setting of ischaemia, necrosis and perforation.
· Fever.
·Tachycardia.

Question 11

If you suspected a patient had a small bowel obstruction, what investigations would you request?

Answer 11

· Abdominal x-ray:

• Air-fluid levels.
• Dilated intestinal loops.
• Absence of gas in the rectum in complete SBO.
• Pneumoperitoneum.

· FBC:
- Increased WCC.

· Urea:
- Shows severity of dehydration.

· U&Es.

Question 12

Suggest some differential diagnoses.

Answer 12

· Ileus. 
· Infectious gastroenteritis. 
· Large bowel obstruction. 
· Intestinal pseudo-obstruction.
· Appendicitis. 
· Pancreatitis.

Question 13

What is the treatment option for a patient who has a complete/complicated/strangulated SBO and is a surgical candidate?

Answer 13

· 1st line - Emergency laparotomy plus fluid resuscitation.

· Plus - Pre-op abx prophylaxis.

· Plus - NG decompression.

· Plus - Analgesia.

· Plus - Correction of the underlying cause.

Question 14

What is the treatment option for a patient who has a complete/complicated/strangulated SBO but surgery is contraindicated?

Answer 14

· 1st line - NG decompression plus fluid resuscitation.

· Plus - Analgesia.

· Adjunct - Anti-emetics.

· Adjunct - Anti-spasmodic.

Question 15

What is the treatment option for a patient who has a partial SBO?

Answer 15

· 1st line - NG decompression plus fluid resuscitation.

· Plus - Correction of the underlying cause.

· Plus - Analgesia.

· If poor clinical response in 48-72 hours, surgery.

Question 16

What complications can arise?

Answer 16

· Intestinal necrosis.
· Sepsis. 
· Multi-organ failure. 
· Intra-abdominal abscess.
· Short bowel syndrome.
· Intestinal perforation.