What is the primary method for diagnosing nephrolithiasis?

The primary method for diagnosing nephrolithiasis, or kidney stones, is the noncontrast helical CT scan. This imaging technique is favored because of its high sensitivity and specificity, allowing for accurate identification of the presence, size, and location of the stones within the urinary tract. It provides a comprehensive view without the interference of contrast dye, making it especially useful in acute settings where rapid diagnosis is crucial. Noncontrast CT scans can detect even small stones that may be missed by other modalities.

In contrast, while X-ray of the abdomen can sometimes visualize larger stones, it may not detect all types of stones, particularly those that are radiolucent, such as uric acid stones. Ultrasound is a safer option, especially in pediatric populations or during pregnancy, but it is less definitive than CT for diagnosing nephrolithiasis. Blood tests for calcium levels can help determine underlying metabolic causes of stone formation, but they do not provide direct information about the presence of stones themselves.