What does mild fullness of the right renal collecting system without definite obstructing calculi mean ?

Minimal swelling: Swelling of major urine ducts between collecting tubules and kidney pelvis, which 'funnel' draining all urine from kidney into the ureter. Mild fullness, usually within normal limits. Can signify minimal partial kidney obstruction from an anatomic narrowing, or from infection. Can also be from ureteral obstruction at bladder level, bladder neck ot urethra or bladder reflux or hight urine flow rate.