Diagnostic imaging in stone disease

Initial evaluation

When stone disease is suspected, we must answer four questions:

1. Does the patient really have a stone?
2. Where is the stone?
3. Is it causing obstruction?
4. Is there any complication that requires urgent treatment?

The evaluation includes medical history, physical examination, urinalysis, and blood tests depending on the clinical context. The EAU recommends a brief biochemical evaluation of blood and urine in patients presenting urgently with urolithiasis.

Ultrasound

It has great advantages:

• it uses no radiation;
• it is accessible;
• it can identify dilation of the urinary tract;
• it can detect kidney stones and some ureteral stones;
• it is especially useful in situations where we want to avoid radiation.

However, a normal ultrasound does not completely exclude a ureteral stone.

The EAU maintains ultrasound as the initial study, but recommends confirmation with non-contrast CT when appropriate in patients with acute flank pain.

Non-contrast CT

Non-contrast CT is currently the most useful study for confirming stone disease in adults with renal colic when it is indicated.

It shows:

• presence of the stone;
• number;
• size;
• location;
• density;
• degree of obstruction;
• surrounding anatomy.

It can also identify other causes of pain when there is no stone.

The 2026 EAU Guidelines consider it superior to intravenous urography and ultrasound for confirming a stone in the setting of acute flank pain.

When do we need urgent imaging?

Special attention is needed when there is:

• fever;
• solitary kidney;
• uncertain diagnosis;
• worsening renal function;
• suspected complication;
• persistent pain or a concerning clinical situation.

According to the EAU, the presence of fever or a solitary kidney is specifically an indication for immediate imaging evaluation.