A 54-year-old male with right flank pain severe enough to induce vomiting; he was sitting and watching TV when it started. What is the most likely diagnosis?

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

Answer: (D)

Pain from a kidney stone typically comes on suddenly as severe, sharp flank pain that may move toward the groin, and it is often accompanied by nausea and vomiting. This pattern fits renal colic caused by a stone obstructing the ureter, which triggers intense ureteral spasms and a strong autonomic nausea response. The pain is usually unilateral and focused in the flank, unlike gallbladder pain, which is more in the right upper quadrant and linked to meals, or urinary tract infection symptoms, which center on burning with urination, frequency, or fever. Bladder cancer tends to present with painless blood in the urine rather than sudden intense flank pain. So the combination of sudden, severe unilateral flank pain with vomiting best points to renal calculi.

In practice, manage with prompt pain relief and antiemetics as you arrange transport, and monitor for signs of obstruction or infection.