Wikipedia
Retrograde pyelogram is a urologic procedure where the physician injects contrast into the ureter in order to visualize the ureter and kidney. The flow of contrast (up from the bladder to the kidney) is opposite the usual flow of urine, hence the retrograde name.
Reasons for performing a retrograde pyelogram include identification of filling defects (e.g. stones or tumors), as an adjunct during the placement of ureteral stents or ureteroscopy, or to delineate renal anatomy in preparation for surgery. Retrograde pyelography is generally done when an intravenous excretory study (IVP or contrast CT scan) cannot be done because of renal disease or allergy to intravenous contrast.
Relative contraindications include the presence of infected urine, pregnancy and contrast allergy.
The procedure requires cystoscopy and the placement of a small tube into the lower part of the ureter to inject contrast and opacify the ureter and renal pelvis. Fluoroscopy, or dynamic X-Rays, is typically used for visualization. The procedure is usually done under general or regional anesthesia.