What structure can cause severe flank pain if kidney stones block it?

What structure can cause severe flank pain if kidney stones block it?

• A. Bladder
• B. Urethra
• C. Ureter
• D. Renal pelvis

Answer: (C)

When a kidney stone blocks the ureter, it causes renal colic—the sudden, severe, flank pain that often radiates toward the groin. The ureter is the muscular tube that carries urine from the kidney’s collecting system down to the bladder. If a stone lodges there, the proximal ureter and renal pelvis become distended, and the ureter undergoes vigorous peristaltic contractions as it tries to move the stone. This combination of distension and muscle activity triggers intense pain that follows the autonomic nerve supply (usually presenting as waves of pain in the flank that can travel to the groin). The ureter is a common narrow point for stones to lodge, which is why this structure is classically linked to such severe flank pain. Obstruction at the bladder or urethra tends to produce urinary symptoms rather than this characteristic unilateral flank pain, and a stone in the renal pelvis can cause pain too, but the most classic source of that severe colicky pain is blockage of the ureter.

When a kidney stone blocks the ureter, it causes renal colic—the sudden, severe, flank pain that often radiates toward the groin. The ureter is the muscular tube that carries urine from the kidney’s collecting system down to the bladder. If a stone lodges there, the proximal ureter and renal pelvis become distended, and the ureter undergoes vigorous peristaltic contractions as it tries to move the stone. This combination of distension and muscle activity triggers intense pain that follows the autonomic nerve supply (usually presenting as waves of pain in the flank that can travel to the groin). The ureter is a common narrow point for stones to lodge, which is why this structure is classically linked to such severe flank pain. Obstruction at the bladder or urethra tends to produce urinary symptoms rather than this characteristic unilateral flank pain, and a stone in the renal pelvis can cause pain too, but the most classic source of that severe colicky pain is blockage of the ureter.