What are the causes of hematuria during endovascular aneurysm repair (EVAR)?

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Last updated: March 12, 2026 • View editorial policy

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Causes of Hematuria During EVAR

Hematuria during EVAR is most commonly caused by urethral catheter trauma, but can also indicate catastrophic aortocaval fistula formation requiring immediate investigation.

Primary Mechanism: Urethral Catheterization Trauma

  • Prostatic trauma from urethral catheter placement is the leading iatrogenic cause of hematuria during EVAR, occurring as a direct mechanical injury during catheter insertion 1.
  • Routine preoperative urinary catheter placement carries inherent risks of urethral injury and prostatic trauma that can manifest as intraoperative hematuria 1.
  • The catheterization itself—not the EVAR procedure—is the culprit in most cases of procedural hematuria 1.

Clinical Implication

  • Selective rather than routine catheter placement should be employed to minimize urinary-related complications, as catheterized patients show over two-fold higher rates of urinary retention (10.9% vs 4.6%) and nearly 2.5-fold increased UTI risk 1.
  • Many percutaneous EVARs can be performed safely without urinary catheterization, eliminating this source of hematuria entirely 1.

Critical Differential: Aortocaval Fistula

  • Hematuria is a constant finding (100% of cases) when an abdominal aortic aneurysm ruptures into the vena cava, making it a more reliable sign than the classic triad of pulsatile mass, bruit, and high-output heart failure 2.
  • Macrohematuria occurred in 55% and microhematuria in 45% of aortocaval fistula cases, with mean operative blood loss reaching 7 liters 2.
  • The presence of hematuria in any patient with an abdominal aortic aneurysm mandates aortography to rule out aortocaval fistula before or during EVAR 2.

Recognition Algorithm

  • If hematuria develops during EVAR with hemodynamic instability or unexplained blood loss, immediately suspect aortocaval fistula 2.
  • Distinguish between minor catheter-related bleeding (typically self-limited, small volume) versus persistent or large-volume hematuria suggesting vascular communication 2.

Other Procedural Complications

  • Access vessel injury during femoral access can rarely cause retrograde bleeding into the urinary tract if there is inadvertent injury to adjacent structures 3.
  • Systemic complications and bleeding diathesis from massive transfusion or coagulopathy during complicated EVAR can manifest as hematuria 3.

Post-Procedure Considerations

  • Patients who develop urinary retention post-EVAR have an 18-fold increased risk of UTI (adjusted OR 17.98, p=0.019), which can present with secondary hematuria 1.
  • Increased intraoperative blood loss (p=0.027) correlates with higher UTI rates, creating a pathway to delayed hematuria 1.

Critical Pitfall to Avoid

  • Never attribute intraoperative hematuria solely to catheter trauma without excluding aortocaval fistula, especially if accompanied by hemodynamic changes, high-output cardiac state, or unexplained blood loss exceeding typical EVAR parameters 2.
  • Do not assume anticoagulation explains the bleeding without completing vascular imaging, as this can miss a surgical emergency 4.
  • Microscopic confirmation that bleeding represents true hematuria (not hemoglobinuria from massive hemolysis) should be documented 4.

References

4
Guideline

Urgent Evaluation of Single‑Episode Gross Hematuria in End‑Stage Renal Disease

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.