What is the initial treatment approach for a patient with abdominal pain, vomiting, and air-fluid levels on imaging?

Management of Bowel Obstruction with Air-Fluid Levels

The initial treatment approach for a patient with abdominal pain, vomiting, and air-fluid levels on imaging should be nasogastric (NG) tube decompression. 1, 2

Initial Management

• NG tube decompression is the first-line intervention to relieve pressure, reduce vomiting risk, and improve respiratory status in patients with suspected bowel obstruction 1, 2
• Intravenous fluid resuscitation with crystalloids should be initiated immediately to address dehydration and electrolyte imbalances 1, 2
• Insertion of a Foley catheter to monitor urine output as a marker of adequate resuscitation is recommended 2
• Bowel rest (nothing by mouth) should be maintained until clinical improvement 1
• Anti-emetics can be administered to help manage symptoms 1

Diagnostic Considerations

• Air-fluid levels on direct radiography strongly suggest bowel obstruction, with a sensitivity of 50-60% 1
• The presence of abdominal distension has a positive likelihood ratio of 16.8 for bowel obstruction 1
• Evaluate for signs of peritonitis, which may indicate strangulation or ischemia, although physical examination has only 48% sensitivity for strangulation 1
• Check vital signs for indications of shock, which could suggest severe obstruction, perforation, or ischemia 1

Further Evaluation

• After initial NG decompression, CT scan with IV contrast should be considered as it has superior diagnostic accuracy (>90%) compared to plain radiography and can identify complications like ischemia or perforation 1, 2
• Signs of ischemia on CT include abnormal bowel wall enhancement, bowel wall thickening, mesenteric edema, pneumatosis, or mesenteric venous gas 2
• Laboratory tests should include complete blood count (leukocytosis >10,000/mm³ suggests peritonitis), electrolytes (low potassium is common), renal function tests, and lactate levels (elevated in intestinal ischemia) 1

Surgical Considerations

• Immediate surgical consultation should be obtained while initiating medical management 1, 2
• Emergent laparotomy is indicated if there are signs of:
  • Peritonitis on clinical examination 1, 2
  • Bowel ischemia or strangulation on imaging 1, 2
  • Failure to respond to conservative management 1
  • Closed loop obstruction 2
  • Free intraperitoneal fluid suggesting perforation 2

Common Pitfalls to Avoid

• Delaying NG tube decompression can worsen distension and increase risk of aspiration 1, 2
• Mistaking incomplete obstruction with watery diarrhea for gastroenteritis can lead to delayed diagnosis and treatment 1
• Overlooking bowel obstruction in elderly patients where pain may be less prominent 1
• Failing to correct electrolyte abnormalities before surgical intervention can increase complication risk 1
• Delaying surgical intervention when signs of peritonitis, strangulation, or ischemia are present significantly increases morbidity and mortality 2

Monitoring Response

• After NG tube placement, monitor for reduction in abdominal distension and improvement in symptoms 2
• Persistent vomiting or increasing abdominal distension despite NG decompression suggests high-grade obstruction that may require surgical intervention 1, 2
• Serial abdominal examinations should be performed to detect developing peritoneal signs 1