What is the recommended imaging approach for suspected splenic sequestration?

Imaging for Splenic Sequestration

CT scan with intravenous contrast is the gold standard for diagnosing splenic sequestration, showing characteristic patterns of multiple peripheral non-enhancing low-density areas or large diffuse areas of low density throughout the splenic tissue. 1

Initial Diagnostic Approach

Hemodynamic Assessment

• First determine patient's hemodynamic status:
  • Stable patients: Proceed with comprehensive imaging
  • Unstable patients: Use bedside ultrasound (E-FAST) to rapidly identify splenic enlargement and intraperitoneal hemorrhage 2

Imaging Algorithm

1. Ultrasound (First-line)

   • Advantages:
     • Non-invasive, no radiation exposure
     • Can detect splenomegaly, assess splenic texture and vasculature
     • Useful when clinical suspicion is low or in pediatric patients 2, 3
   • Findings in sequestration:
     • Splenic enlargement
     • Irregular hypoechoic areas at periphery of spleen 4
   • Limitations:
     • Lower sensitivity (50-92%) compared to CT 2
     • Operator-dependent
     • May miss subtle findings

2. CT with IV Contrast (Gold Standard)

   • Indications:
     • Hemodynamically stable patients
     • Inconclusive ultrasound findings
     • High clinical suspicion despite normal ultrasound 2
   • Characteristic findings:
     • Two distinct patterns:
       1. Multiple peripheral non-enhancing low-density areas
       2. Large diffuse areas of low density throughout splenic tissue 1
     • Splenic enlargement
   • Advantages:
     • Highest sensitivity and specificity (96-100%) 2
     • Can detect other abdominal pathologies
     • Can identify complications (rupture, infarction)

3. Doppler Ultrasound and Contrast-Enhanced Ultrasound (CEUS)

   • Useful for:
     • Evaluating splenic vascularization
     • Follow-up after initial diagnosis 2
     • Detecting pseudoaneurysms (PSA) 2

Special Considerations

Pediatric Patients

• Ultrasound is preferred initial test to minimize radiation exposure 2
• Low-dose CT protocols (3-6 mSv) should be used when CT is necessary 2
• Important note: Splenic sequestration can occur without palpable splenomegaly, so imaging is crucial when clinical suspicion is high 5

Adults with Sickle Cell Disease

• Though less common in adults, splenic sequestration can occur in heterozygous sickle cell conditions like HbS/β+-thalassemia 4
• CT and ultrasound findings are similar to those in pediatric patients

Follow-up Imaging

• For patients with chronic liver disease and splenomegaly:
  • Complete blood count every 3-6 months
  • Abdominal ultrasound every 6 months 6
• For patients with known splenic sequestration:
  • Doppler US and CEUS are useful for follow-up evaluation 2

Pitfalls to Avoid

1. Relying solely on physical examination - splenic sequestration can occur without palpable splenomegaly 5
2. Delaying imaging in unstable patients - use bedside E-FAST immediately 2
3. Misinterpreting contrast blush on CT - not an absolute indication for intervention, especially in children 2
4. Overlooking the need for follow-up imaging in patients with recurrent episodes 7

By following this evidence-based imaging approach, clinicians can promptly diagnose splenic sequestration, which is crucial for timely intervention and improved patient outcomes.