Small Bowel Obstruction

Question 1

Definition of small bowel obstruction

Answer 1

Is a mechanical disruption in the patency of the small bowel

Question 2

Aetiology of small bowel obstruction

Answer 2

• There are many causes of small bowel obstruction:
◦ Adhesions (most common)
◦ Hernias: external or internal
◦ Neoplasms
◦ Crohn’s disease
◦ Appendicitis

• Bowel can have simple obstruction (no damage to blood supply
• Or it can be strangulating obstruction (blood supply cut off, e.g due to strangulated hernia, volvulus etc)

• Untreated obstruction can lead to progressive intestinal ischaemia, necrosis and perforation

Question 3

History and Examination of small bowel obstruction

Answer 3

• Colicky abdominal pain: cramping, intermittent and severe
• Nausea and vomiting: earlier sign in small bowel obstruction, can be bilious vomiting
• Abdominal distention
• Anorexia
• Abdominal mass may be felt
• Peritonitis
• Constipation/failure to pass flatus: later sign in small bowel obstruction, may not be absolute constipation
• Tinkling bowel sounds

Question 4

Investigations for small bowel obstruction

Answer 4

• Check for hernias and abdominal scars
• Erect AXR and CXR:
◦ Centrally dilated bowels
◦ May be able to see valvular conniventes (circular mucosal folds)
◦ May look like ladders
• CT abdo pelvis: definitive investigation that can establish the cause of obstruction (tumour, appendicitis, hernia etc)
• Water soluble contrast study: may not be able to see contrast in some areas due to obstruction
• ABG: check for lactate levels to see if there is intestinal ischaemia
• FBC: strangulation/perforation

Question 5

Treatment of small bowel obstruction

Answer 5

General:
1) Supportive care:
◦ FLUID RESUSCITATION and NG TUBE DECOMPRESSION
◦ Give analgesia if required
◦ Patient NBM

CONSERVATIVE:
• Faecal impaction (can evacuate the stool using enema, manual, endoscopic)
• Oral gastrograffin for small bowel obstruction due to adhesions

SURGERY INDICATED (ischaemia, perforation risk):
1) Emergency surgery: strangulation is a surgical emergency (can be laparoscopic or open). May require bowel resection and anastomosis/stoma formation

Question 6

Complications and prognosis of small bowel obstruction

Answer 6

• Intestinal necrosis
• Sepsis
• Multi-organ failure
• Intestinal perforation

Timely treatment allows for good prognosis. Surgery can increase the risk of later obstruction due to more adhesions