Could you explain the term "retrograde pyelogram" to me?

Exam by doctor: In a retrograde pyelogram a urologist will place a small tube through your bladder up the ureters and inject contrast to visualize the size and shape of the ureters. You will be sedated during the procedure.

Pyelogram: Is an invasive procedure in which you place a cystoscope through the urethra, then pass a small catheter through the scope into the opening of the ureter into the bladder and inject contrast material into the kidney to study the anatomy of the drainage system of the kidney and take x.-rays usually under fluoroscopic control.