A patient had passed a 4mm stone in his urine. He has a 3mm stone in the renal pelvis found on US. What is the management?

The key is B. None.

• [Stones less than 5 mm in diameter pass spontaneously in up to 80% of people. • Stones between 5 mm and 10 mm in diameter pass spontaneously in about 50% of people. • Stones larger than 1 cm in diameter usually require intervention (urgent intervention is required if complete obstruction or infection is present).

• Two thirds of stones that pass spontaneously will do so within four weeks of onset of symptoms]. Ref: patient.info