A 52-year-old man with a history of three prior abdominal surgeries presents with acute-onset colicky abdominal pain, abdominal distension, and vomiting. On examination, he is afebrile, with a soft abdomen and visible peristaltic waves. Bowel sounds are hyperactive and high-pitched. Plain abdominal X-ray shows dilated small bowel loops with air-fluid levels in a "staircase" pattern and no free air. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Adhesive Small Bowel Obstruction ### Key Clinical Features **Key Point:** The triad of colicky pain, vomiting, and abdominal distension in a patient with prior abdominal surgery is pathognomonic for adhesive obstruction. ### Why This Patient Has Adhesive SBO 1. **Risk Factor**: Three prior abdominal surgeries create adhesions in 60–75% of patients; adhesions cause 60–75% of all small bowel obstructions in developed countries. 2. **Clinical Presentation**: Colicky (intermittent) pain is typical of mechanical obstruction, distinguishing it from ileus or vascular compromise. 3. **Examination Findings**: - Hyperactive, high-pitched bowel sounds = mechanical obstruction - Soft, non-tender abdomen = no peritonitis (rules out perforation) - Visible peristaltic waves = bowel attempting to overcome obstruction 4. **Imaging Pattern**: Dilated small bowel with air-fluid levels in a "staircase" configuration is classic for mechanical SBO; absence of free air excludes perforation. ### Pathophysiology of Adhesions **High-Yield:** Adhesions form during the healing phase (7–14 days post-op) when fibrin deposition is not fully resorbed. They are the most common cause of recurrent SBO. ### Management Approach ```mermaid flowchart TD A[Adhesive SBO suspected]:::outcome --> B{Signs of peritonitis or shock?}:::decision B -->|Yes| C[Emergency surgery]:::urgent B -->|No| D[Conservative management trial]:::action D --> E[NPO, NG tube, IV fluids]:::action E --> F{Resolution in 24-48 hrs?}:::decision F -->|Yes| G[Discharge, counsel on recurrence]:::outcome F -->|No| H[Surgical exploration]:::action ``` **Clinical Pearl:** Approximately 70–80% of partial adhesive obstructions resolve with conservative management (nasogastric decompression, bowel rest, fluid resuscitation). Surgery is reserved for complete obstruction, peritonitis, or failure of conservative therapy after 48–72 hours. ### Why Not the Other Options | Diagnosis | Why Excluded | |-----------|-------------| | **Acute pancreatitis** | No mention of epigastric pain, elevated amylase/lipase; peristaltic waves and high-pitched bowel sounds are not typical | | **Perforated peptic ulcer** | Free air would be visible on X-ray; abdomen is soft and non-tender; no mention of sudden severe pain | | **Acute mesenteric ischemia** | Typically presents with severe pain out of proportion to exam; bowel sounds are diminished or absent; patient would appear toxic | [cite:Sabiston Textbook of Surgery Ch 45]