Which imaging study visualizes the urinary tract by injecting contrast through the urethra?

• A. Semen analysis
• B. Retrograde pyelogram
• C. PSA
• D. Peritoneal dialysis

Answer: (B)

This question tests the concept that retrograde pyelography visualizes the urinary tract by introducing contrast via the urethra into the bladder and then up into the ureters. A catheter is placed through the urethra during cystoscopy, contrast is injected in a retrograde fashion, and radiographs outline the ureters and renal collecting system. This method is particularly useful when intravascular contrast is not suitable or when assessing ureteral or pelvic anatomy during endourologic procedures. The other options are not imaging studies of the urinary tract: semen analysis assesses fertility, PSA is a blood test for prostate pathology, and peritoneal dialysis is a treatment modality.