What imaging modality is recommended after cystoscopy and cytology to complete the workup for microscopic hematuria in a patient with impaired renal function?

Imaging Recommendations for Microscopic Hematuria Workup in a Patient with Impaired Renal Function

For a patient with CKD and eGFR of 36, MR urography without and with IV contrast is the most appropriate imaging modality to complete the workup for microscopic hematuria after cystoscopy and cytology. 1

Risk Assessment and Imaging Selection Algorithm

Patient Risk Factors

• 68-year-old male with microscopic hematuria (RBC 11-30) places him in the intermediate-to-high risk category for urologic malignancy 1
• CKD with eGFR of 36 ml/min presents a significant risk for contrast-induced nephropathy with iodinated contrast 2
• History of elevated PSA and BPH increases risk for urologic pathology 3
• Atrophic right kidney and bilateral renal vascular calcification indicate underlying renal disease 4

Imaging Selection Based on Renal Function

• For patients with impaired renal function (eGFR <45 ml/min), CT urography with iodinated contrast carries significant risk of contrast-induced nephropathy 2
• The 2020 AUA/SUFU guidelines recommend MR urography when there are contraindications to multiphasic CT urography 1
• The American College of Radiology indicates that MR urography without and with IV contrast is usually appropriate for hematuria evaluation in patients with contraindications to CT contrast 1

Specific Imaging Recommendations

First-Line Option: MR Urography

• MR urography without and with IV contrast provides comprehensive evaluation of the upper urinary tract without risk of contrast-induced nephropathy 1
• Protocol should include:
  • Heavily T2-weighted sequences for evaluation of the collecting system 1
  • Pre-contrast T1-weighted imaging 1
  • Post-contrast sequences including corticomedullary, nephrographic, and excretory phases 1
  • Thin-slice acquisition and multiplanar imaging 1

Alternative Option if MRI Contraindicated

• Retrograde pyelography in conjunction with non-contrast CT or renal ultrasound 1
• This combination allows evaluation of both the renal parenchyma and the urothelium without nephrotoxic contrast 1

Rationale for MR Urography Over Other Modalities

Advantages over CT Urography

• Avoids risk of contrast-induced nephropathy in a patient with eGFR of 36 2
• Comparable accuracy to CT in detection and characterization of renal masses 1
• Can adequately evaluate the upper urinary tract for malignancy 1

Advantages over Ultrasound Alone

• Superior to ultrasound for detection of small urothelial lesions 1
• Better characterization of complex renal lesions 1
• More comprehensive evaluation of the collecting system 1

Advantages over Non-Contrast CT

• Ability to evaluate the urothelium with contrast enhancement 1
• Better tissue characterization for potential malignancies 1

Important Considerations and Precautions

• Gadolinium-based contrast agents should be used with caution in patients with severe renal impairment (eGFR <30 ml/min) due to risk of nephrogenic systemic fibrosis 2
• For this patient with eGFR of 36, the risk is lower but still requires consideration of macrocyclic gadolinium agents which have lower risk profiles 2
• If MRI is absolutely contraindicated (e.g., pacemaker, metal implants), retrograde pyelography with non-contrast CT is the next best option 1

Follow-Up Recommendations

• If imaging reveals no significant findings, continued monitoring is recommended with repeat urinalysis at 6,12,24, and 36 months 4, 3
• Additional evaluation should be considered if there is development of gross hematuria, significant increase in degree of microscopic hematuria, or new urologic symptoms 1