Bowel Obstruction

Question 1

Cardinal features of intestinal obstruction

Answer 1

• vomiting
• colicky pain
• constipation (absolute)
• distension

Question 2

Small Bowel obstruction - causes

Answer 2

• post-surgical adhesions (union of two opposing tissue surfaces e.g. scar tissue at the site of operation)
• hernias
• caecum volvulus
• caecal carcinoma
• small bowel ischaemia

Question 3

Small bowel obstruction - features

Answer 3

• acute-gradual
• high-pitched, active, tinkling bowel sounds
• vomiting occurs early on
• distension is less
• pain higher up in the abdomen and colicky
• severe fluid and electrolyte imbalance
• AXR = central gas shadows with valvulae conniventes that completely cross the lumen and no gas in large bowel

Question 4

Large bowel obstruction - causes

Answer 4

• Colon cancer
• strictures from IBD or diverticular disease
• sigmoid volvulus
• intussusception
• adhesions

Question 5

Large bowel obstruction - features

Answer 5

• gradual
• normal bowel sounds
• vomit later on, can be feculent
• early, intense abdo distension
• pain is more constant
• can have severe constipation
• AXR = peripheral gas shadows proximal to blockage (eg in caecum) but not in rectum. Haustra do not cross the whole lumen’s width

Question 6

What is an ileus?

Answer 6

Functional obstruction from reduced bowel motility (not mechanical)

• causes: post surgery, IBD, bowel cancer, diverticulitis, PD, drugs (opioids, TCAs etc) - post anaesthesia
• no pain and bowel sounds are absent
• inhibition of peristalsis (smooth muscle dysfunction)
• both SBO and ileus present as dilated loops of bowel with air-fluid levels

Question 7

Investigations

Answer 7

• bloods (FBC, U+E, amylase etc)
• AXR
• erect CXR
• early CT if findings are inconclusive - may show dilated, fluid filled bowel
  (Oral gastrografin can help identify small bowel obstruction on contrast CT)
• consider colonoscopy for cases of mechanical obstruction eg hernia, volvulus, tumour (though danger of perforation)

Question 8

Initial management

Answer 8

• “drip and suck”: NGT and IV fluids to rehydrate and correct electrolyte imbalance
• analgesia
• oxygen
• catheterise to monitor fluid status
  (get bloods and relevant Ix)

Question 9

Surgery

Answer 9

• broad-spectrum Abx given pre-operatively:
• Surgery: The obstruction is removed to relieve pain and improve the patient’s quality of life.
• Stent: A metal tube inserted into the intestine to open the area that is blocked.

Indications for surgery: bowel perforation, impending perforation, volvulus, coloractal malignancy, complicated diverticular disease, any complete SBO