An obstruction of the PUJ is when the kidney makes urine faster than it can be drained through the renal pelvis into the ureter. This causes urine to pool within the kidney and causes the kidney to swell (hydronephrosis).
This can be a congenital condition or due to previous surgery. You will require further investigation with a dedicated renal Ct scan and a MAG3 scan, which assesses the function and drainage of your kidney.
If you are symptomatic from this, or there is deterioration of your renal function, then you will most likely require a robotically assisted pyeloplasty.