This paper summarises the current evidence for and use of various imaging modalities for investigating haematuria. The following investigations are reviewed:
- Intravenous urogram (IVU) – the number of centres still using IVU is decreasing. IVU is cheaper and has less radiation exposure (~3mSv) than CT but it has a lower sensitivity (61% vs. 86%) and specificity (75% vs. 92%) than CT. Also, if found to be positive patients will still need to have a CT for staging purposes. It therefore suggests that it may soon be a historical investigation.
- Ultrasound (US) – widely available and cheap in addition to being radiation-free. IV contrast is also not required. US can be poor at diagnosing renal masses <3cm and has a reduced sensitivity compared to CT in stone disease, especially for diagnosing ureteric stones (61% vs. 97%).
- CT urography (CTU) – the advantages of CT are that it has a high sensitivity and specificity for diagnosing upper tract malignancies and it can also diagnose extra-urinary pathology (in as high as 56% of cases). The main disadvantage is the radiation dose (~15mSv) for a standard triple phase CT. In order to try and reduce this ‘split-bolus’, protocols have been introduced so only two phases are required. CT also requires the use of iodinated IV contrast which can be nephrotoxic.
- Magnetic resonance urography (MRU) – doesn’t require radiation and T2 images can be particularly useful in demonstrating the collecting system in a poorly excreting kidney. MRU is poor at diagnosing stones though, and appearances of renal cell carcinomas (RCC) can vary.
- The future – contrast enhanced ultrasound (CEUS). Already used in liver malignancy but all studies in haematuria so far compare with US rather than CT. 3D US also seems to be showing promising results.