SMLEREVISE

Nephrolithiasis (Kidney Stones): Evaluation and Management

Medically Reviewed by Dr. M. Salar Raza | Official SCFHS 2026 Blueprint

Clinical Pathway

Nephrolithiasis typically presents with acute, severe, colicky flank pain that may radiate to the groin, often accompanied by hematuria, nausea, and vomiting. The gold standard imaging modality for diagnosing kidney stones is a non-contrast CT scan of the abdomen and pelvis. It offers high sensitivity and specificity for detecting stones, determining their size and location, and identifying associated complications like hydronephrosis. Initial management focuses on pain control (NSAIDs or opioids) and hydration. Stones smaller than 5mm often pass spontaneously.

Clinical Reasoning

A non-contrast CT is preferred over ultrasound or KUB x-ray because it can detect almost all types of stones (including radiolucent stones like uric acid stones, which may be missed on KUB) and provides precise anatomical detail. Ultrasound is a reasonable alternative in pregnant patients or children to avoid radiation exposure, but it is less sensitive for small stones or ureteral stones. For acute pain management, NSAIDs like ketorolac are often preferred over opioids as they directly decrease ureteral smooth muscle tone by inhibiting prostaglandin synthesis.

Sample MCQ

A 40-year-old man presents to the emergency department with sudden onset of severe, colicky right flank pain that radiates to his right groin. He cannot sit still and is constantly pacing the room. Urinalysis shows microscopic hematuria. What is the most appropriate imaging study to confirm the suspected diagnosis?

  • AKidney, ureter, bladder (KUB) X-ray
  • BRenal ultrasound
  • CNon-contrast CT scan of the abdomen and pelvis
  • DIntravenous pyelogram (IVP)

Correct Answer: Non-contrast CT scan of the abdomen and pelvis

The patient's presentation of colicky flank pain radiating to the groin with hematuria is classic for nephrolithiasis (renal colic). The gold standard and most appropriate imaging modality for suspected kidney stones is a non-contrast CT scan. It is highly sensitive and specific, can detect all types of stones, and provides information on size, location, and obstruction. KUB misses radiolucent stones and small stones. Ultrasound is less sensitive for ureteral stones. IVP is rarely used today due to the superiority of CT.

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