What is the most appropriate initial investigation for a 65-year-old male patient with a history of hemicolectomy (surgical removal of part of the colon) for cancer of the cecum (caecum), presenting to the emergency room (ER) with abdominal pain and vomiting, and a distended but soft abdomen?

Appropriate Investigation for a 65-Year-Old Male with Bowel Obstruction After Hemicolectomy

CT scan of the abdomen and pelvis with IV contrast is the most appropriate initial investigation for this patient presenting with abdominal pain, vomiting, and distended abdomen one year after hemicolectomy for cecal cancer. 1

Clinical Assessment of the Presentation

This patient's presentation strongly suggests small bowel obstruction (SBO), which is a common complication following abdominal surgery:

• History of hemicolectomy for cecal cancer (high-risk factor for adhesions)
• Acute onset of abdominal pain and vomiting for 2 days
• Distended but soft abdomen

Key Diagnostic Considerations

1. Adhesive SBO - Most likely cause given history of prior abdominal surgery
2. Tumor recurrence - Important consideration given history of cecal cancer
3. Internal hernia - Possible complication after abdominal surgery
4. Anastomotic stricture - Can occur at the surgical site

Diagnostic Algorithm

First-Line Investigation: CT Scan with IV Contrast

CT scan of the abdomen and pelvis with IV contrast is the investigation of choice because:

• It has high sensitivity (93-96%) and specificity (93-100%) for confirming bowel obstruction 2
• It can identify the cause (66-87%) and site (90-94%) of obstruction 2
• It can detect complications such as ischemia, strangulation, or closed-loop obstruction 2
• It can identify tumor recurrence, which is crucial given the patient's cancer history 2

Why Other Options Are Less Appropriate:

1. Small bowel series (A):

   • Inferior to CT for detecting SBO
   • Requires oral contrast which may worsen obstruction or increase risk of aspiration 2
   • Cannot reliably detect complications like strangulation 1

2. Barium enema (B):

   • Contraindicated in suspected complete obstruction
   • Risk of perforation and barium peritonitis
   • Limited utility in evaluating small bowel pathology 2

3. Colonoscopy (C):

   • Invasive procedure with risk of perforation
   • Limited value in acute obstruction
   • Cannot evaluate the small bowel adequately
   • Contraindicated in acute complete obstruction 2

4. Laparotomy (D):

   • Too invasive as an initial diagnostic procedure
   • Should be reserved for patients with clear indications for surgical intervention
   • Appropriate only after diagnostic imaging confirms necessity 2

Management Considerations

After obtaining the CT scan:

1. Initial management:

   • IV fluid resuscitation
   • Nasogastric tube placement for decompression if significant vomiting or distension
   • Pain management
   • Close monitoring of vital signs and abdominal examination

2. Surgical consultation:

   • Early involvement of surgical team is essential 2
   • Surgical intervention may be required if complete obstruction, signs of strangulation, or tumor recurrence are identified

3. Predictors of need for surgery:

   • Complete obstruction on imaging
   • Signs of bowel ischemia or strangulation
   • Failure of conservative management
   • Evidence of tumor recurrence

Important Pitfalls to Avoid

1. Delaying appropriate imaging in a patient with history of cancer and signs of obstruction
2. Using oral contrast in suspected high-grade obstruction (increases risk of aspiration)
3. Failing to consider cancer recurrence in a patient with history of malignancy
4. Prolonging conservative management in patients with signs of strangulation

CT scan without oral contrast but with IV contrast represents the optimal balance of diagnostic accuracy and patient safety in this clinical scenario.