What is the preferred imaging study for investigating renal stones when a patient presents with acute flank pain?

The preferred imaging study for investigating renal stones in a patient presenting with acute flank pain is a non-contrast CT scan. This modality is highly effective for several reasons.

A non-contrast CT scan of the abdomen and pelvis provides excellent sensitivity and specificity for detecting renal stones. It can identify stones of all sizes and helps visualize the urinary tract, allowing for the assessment of any potential complications, such as hydronephrosis or obstruction. The outcome is a rapid and accurate diagnosis, which is critical in managing acute flank pain typically caused by renal colic.

Other imaging modalities, while useful in certain situations, do not match the efficacy of non-contrast CT scans for this specific clinical scenario. For example, X-rays have limited sensitivity for detecting small stones and might miss stones that are not radiopaque. Pelvic ultrasound can be beneficial for evaluating certain aspects of kidney issues, particularly in children or pregnant women, where radiation exposure is a concern, but it is not as definitive for identifying stones. Contrast-enhanced CT scans, while excellent for detailed visualization, are not the initial choice for suspected stones due to the potential risks associated with contrast and the unnecessary complexity in this acute setting.

Overall, the non-contrast CT scan stands out as the diagnostic tool