Fullness of the renal pelvis
suggest back pressure changes. That means there is some obstruction distally. You have 2 urologic issues now.
1. Back pressure changes on the left side requires ascending contrast study to identify the cause of obstruction.
2. Prostatic enlargement with cystitis
merits further investigation and treatment. A TRUS along with estimation of post voiding residue will give the exact status of the prostatic problem . It will serve as a road map for further treatment.
Cystitis is perhaps due to incomplete emptying of the bladder due to the prostatic enlargment. that requires treatment of the prostate
along with a course of antibiotics.
Remember act fast and promptly.