What is the test of choice for diagnosing a strangulated umbilical hernia?

Computed Tomography (CT) with Intravenous Contrast is the Test of Choice for Diagnosing Strangulated Umbilical Hernia

CT scan with intravenous contrast is the test of choice for diagnosing a strangulated umbilical hernia due to its superior diagnostic accuracy and ability to identify complications such as bowel ischemia and necrosis. 1

Diagnostic Algorithm for Suspected Strangulated Umbilical Hernia

Initial Clinical Assessment

• Evaluate for signs of intestinal strangulation:
  • Irreducible, tender hernia
  • Abdominal pain, nausea, vomiting
  • Systemic inflammatory response syndrome (SIRS)
  • Abdominal muscle guarding

Laboratory Tests

• Order these tests to evaluate for strangulation:
  • Complete blood count (elevated WBC may indicate strangulation) 1
  • Serum lactate (≥2.0 mmol/L suggests non-viable bowel) 1
  • CPK (elevated in early intestinal strangulation) 1
  • D-dimer (correlates with intestinal ischemia despite low specificity) 1

Imaging Studies

1. CT scan with IV contrast (first-line):

   • Provides superior diagnostic accuracy for strangulation 1
   • Identifies reduced wall enhancement (56% sensitivity, 94% specificity) 1
   • Detects complications like perforation and peritonitis 1
   • Assists in preoperative planning 1
   • No oral contrast needed as intraluminal fluid/gas serve as natural contrast 1

2. Ultrasound (alternative when CT unavailable):

   • Can detect hernia and bowel obstruction 1
   • Less accurate for determining etiology 1

3. Plain radiography:

   • Limited utility but may show signs of bowel obstruction 1
   • Significantly less sensitive than CT 1

Interpretation of CT Findings in Strangulated Umbilical Hernia

Key Diagnostic Features

• Reduced bowel wall enhancement (most significant predictor) 1
• Bowel wall thickening
• Pneumatosis (indicates ischemia/infarction)
• Free fluid
• Hernia sac contents (commonly peritoneal fat, small bowel) 2

Measurement Parameters

• Document hernia dimensions in three planes:
  • Transversal length
  • Cephalocaudal length
  • Anteroposterior length 2, 3

Special Considerations

Pitfalls in Diagnosis

• High rate of underdiagnosis (63.6-64.8% of umbilical hernias are unreported on CT) 2, 3
• Smaller hernias (average 7.7 × 6.0 mm) are more frequently missed 3
• Content description and complication signs are often omitted in reports 3

Urgent Management

• Immediate surgical intervention is required when strangulation is suspected 1
• Delayed diagnosis beyond 24 hours increases mortality risk 1

Pediatric Considerations

• Strangulation can occur in children as the fascial defect decreases in size 4, 5
• Prompt imaging and surgical intervention are critical 4

CT with intravenous contrast remains the gold standard for diagnosing strangulated umbilical hernias due to its ability to detect bowel wall ischemia and guide surgical management. The high rate of underreporting umbilical hernias on CT scans highlights the importance of careful radiological assessment when this condition is suspected.