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CDHB

Small Bowel Obstruction

This is an emergency - the main danger is bowel strangulation and ischaemia.

Causes

• Adhesions, hernias containing bowel, Crohn's disease, volvulus, neoplasms, foreign bodies, ischaemia.

History and Examination

The findings largely depend on the level of the obstruction. Seek evidence of prior abdominal surgery. Typically there is severe, often sudden, abdominal pain and distension, vomiting and constipation. The abdominal pain is often central and colicky.

Initial Management

• CBC + diff, Na, K, creatinine, LFTs, amylase and lactate. ABGs can be useful if ischaemic bowel is suspected.
• IV fluid resuscitation with sodium chloride 0.9%. Potassium may be required.
• Chest and abdominal X-ray (supine and erect).
• Nasogastric tube.
• Indwelling urinary catheter. Monitor urine output and fluid balance.
• ECG if age >50 yrs.

Management

• Suspected ischaemic bowel: patients with small bowel obstruction may need urgent surgery if bowel ischaemia is suspected. The following clinical presentations may indicate ischaemia:
  • Peritonitis.
  • Fever.
  • Constant severe pain.
  • Raised WBC or CRP.
  • Incarcerated hernia.
  • Metabolic acidosis (pH <7.2 and base excess <-6).
• Patients with a presumed adhesive bowel obstruction with no ischaemic bowel features
  • The majority of patients with an adhesive small bowel obstruction will resolve with conservative management.
  • To decide early which patients will be suitable for conservative management, a water soluble contrast agent is given orally.
    • Give Gastrografin 100 mL PO or NG after the stomach is aspirated. Spigot nasogastric tube for a maximum of 4 hours.
    • Obtain an abdominal X-ray 8 hours following administration of Gastrografin.
    • If contrast is present in the colon, obstruction will resolve in 99% of patients without surgery, therefore conservative management should continue if no signs of ischaemia. Patients can be started on a light diet.
    • Patients with no contrast in colon are unlikely to resolve with conservative management and surgery is likely to be necessary.
• Patients with non-adhesive small bowel obstruction with no signs of ischaemia: these patients should have an abdominal CT scan performed to elucidate cause of the obstruction. This includes patients with:
  • No previous abdominal surgery.
  • Multiple recurrent episodes of small bowel obstruction with no previous CT abdomen.
  • Abdominal malignancy suspected.

Topic Code: 66332