Which condition is most consistent with sudden, severe flank pain that may radiate to the groin and is often accompanied by nausea?

• A. Gallstones
• B. Urinary tract infection
• C. Renal calculi
• D. Pyelonephritis

Answer: (C)

Pain that starts suddenly and is severe in the flank, often moving toward the groin and accompanied by nausea, is a hallmark of renal colic from a kidney stone. The stone irritates and intermittently blocks the ureter, causing intense, cramping pain that can come in waves as the ureter contracts to move the stone. The groin radiation happens because the nerves in the kidney and ureter share pathways with the groin and genitals, so pain can travel along those routes. Nausea is a common reaction to the severe visceral pain.

By contrast, gallstones usually produce pain in the upper right abdomen or back, often after fatty meals, and may involve jaundice or right shoulder blade radiation rather than flank-to-groin radiation. A urinary tract infection tends to cause dysuria, frequency, and sometimes suprapubic discomfort, with fever being possible but the pain profile isn’t the typical sudden, severe, colicky flank pain. Pyelonephritis can cause flank pain too, but it usually comes with fever, chills, and systemic signs rather than a sudden, wave-like, colicky pain radiating to the groin.

So the described pattern—sudden, severe flank pain radiating to the groin with nausea—fits renal calculi best.