Renal colic is best described as severe flank pain caused by kidney stones moving into the ureter, with restlessness and inability to find a comfortable position.

• A. Sudden painless hematuria.
• B. Severe flank pain caused by kidney stones moving into the ureter, with restlessness.
• C. High fever with chills.
• D. Frequent urge to urinate with burning.

Answer: (B)

Renal colic presents with sudden, severe flank or groin pain that occurs as a kidney stone moves into and through the ureter, causing obstruction and smooth muscle spasm. The pain is intense and often described as colicky, coming in waves, which is why the patient is restless and can't find a comfortable position. This description captures the hallmark signs clinicians look for in acute stone passage. Other patterns don’t fit as well: painless sudden blood in the urine isn’t typical when the pain is so prominent; fever with chills suggests an infection rather than simple stone passage; and a frequent urge to urinate with burning points more toward a bladder or urinary tract infection rather than a migrating stone causing ureteral obstruction.