The common approach is to wait for them to pass until they cause pain in either of the flanks .
Instead of waiting for them to flow down to the ureter with high chances of getting them painfully stuck, you can get them removed by ESWL (Lithotripsy)
This is a non-invasive or non cut ,safe procedure for small and medium size stones especially in kidney and upper ureter .
These stones are crushed into dust by shock waves and the dust gets flushed out through urine.
Since these are fine particles crushed at a specific energy of soundwaves, they do not cause obstruction.
The possible outcome without any treatment
In case it flows down to the ureter and flushes out on its own, well and good but if it causes obstruction in the ureter you might have severe pain with disruption in urine flow, which can lead to infection in the kidney.
ESWL in the present world is the first line treatment and is the best and safest way to get rid of these stones in a hassle-free manner
Instead of waiting and watching, it's advisable to get yourself evaluated for Lithotripsy and go ahead with the removal of kidney stone without surgery.