What is the best imaging approach for a patient with Chronic Kidney Disease (CKD) experiencing a Gastrointestinal (GI) bleed?

Imaging Approach for GI Bleeding in Patients with Chronic Kidney Disease

For patients with chronic kidney disease experiencing GI bleeding, CT angiography (CTA) without and with IV contrast is the preferred first-line imaging approach when endoscopy is not feasible or has failed to identify the source of bleeding. 1

Initial Approach

• Endoscopy (esophagogastroduodenoscopy or EGD) remains the first-line diagnostic and therapeutic investigation for GI bleeding, particularly for upper GI bleeding, even in CKD patients 1
• If endoscopy is unsuccessful in achieving initial hemostasis or the patient experiences recurrent bleeding after a successful initial endoscopy, imaging should be considered 1

Imaging Options for CKD Patients with GI Bleeding

CT Angiography (CTA)

• Indications for CTA in CKD patients:

  • When endoscopy is not suitable due to patient instability 1
  • When there is no in-house emergency gastroenterology coverage 1
  • After negative endoscopy or if endoscopy is unable to identify the bleeding site 1
  • In hemodynamically unstable patients as the first diagnostic study 1

• CTA Protocol for CKD patients:

  • Unenhanced images (conventional or virtual noncontrast) should be acquired in all cases 1
  • Images should include late arterial phase and portal venous or delayed phase 1
  • No oral contrast should be administered as it can mask bleeding 1
  • Consider dual-energy CT techniques if available to improve visibility of extravasation sites 1

• Benefits of CTA:

  • Can detect bleeding rates as slow as 0.3 mL/min 1
  • High sensitivity (85%) and specificity (92%) for active GI bleeding 1
  • Faster triage of patients toward definitive treatment compared to other modalities 1

Catheter Angiography (CA)

• Indications for CA in CKD patients:

  • When CTA has identified active extravasation and the patient is unstable 1
  • When endoscopy visualizes but is unable to treat a source of bleeding 1
  • In select cases such as hepatic pseudoaneurysm 1

• Considerations for CA in CKD patients:

  • Patient's renal and coagulation status should be optimized before the procedure 1
  • Superselective embolization should be performed when possible to minimize contrast use 1
  • Technical success rates up to 95%, with clinical success rates around 67% 1

Special Considerations for CKD Patients

• Contrast-induced acute kidney injury (CI-AKI) risk:

  • Optimize renal function before contrast administration 1
  • Consider ultra-low contrast volume protocols in severe CKD patients 2
  • Use of diluted contrast media may help reduce risk 2

• Risk mitigation strategies:

  • Minimize contrast volume by using the lowest diagnostically acceptable dose 3
  • Consider alternative imaging when appropriate 3
  • Discuss with radiologists to determine optimal imaging protocol based on risk-benefit assessment 3

Practical Algorithm for GI Bleeding in CKD Patients

1. First step: Attempt endoscopy if patient is stable and bleeding is suspected to be from upper or lower GI tract 1

2. If endoscopy fails or is not feasible:

   • For hemodynamically unstable patients: Proceed directly to CTA without and with IV contrast 1
   • For stable patients with high suspicion of active bleeding: CTA without and with IV contrast 1

3. If CTA identifies active bleeding:

   • Proceed to catheter angiography with intent to embolize 1
   • Use microcoils as the preferred embolic agent when possible 1

4. If CTA is negative but clinical suspicion remains high:

   • Consider repeat endoscopy if patient is stable 1
   • Consider alternative imaging such as tagged RBC scan for intermittent bleeding 1

Potential Complications and Pitfalls

• Complications of contrast use in CKD:

  • Risk of CI-AKI increases with severity of baseline kidney dysfunction 3
  • Complication rates of angiographic treatment up to 10%, including kidney damage 1

• Common pitfalls to avoid:

  • Delaying angiography after positive CTA can reduce likelihood of identifying bleeding source 1
  • Failing to optimize renal function before contrast administration 1
  • Using excessive contrast volume during procedures 2

• Important note: Recent evidence suggests the risk of CI-AKI may be lower than previously thought in patients with moderate CKD receiving IV contrast, but caution is still warranted in advanced CKD (stages 4-5) 4