What is a retrograde pyelogram?

Retrograde Pyelogram: Definition, Indications, and Procedure

A retrograde pyelogram is a diagnostic imaging procedure that involves introducing water-soluble contrast in a retrograde fashion into the ureter and collecting system of the kidney under fluoroscopic guidance to visualize the urinary tract. 1

Definition and Technique

• Retrograde pyelogram consists of cannulating the ureteral orifice, typically using a 5-Fr universal ureteral catheter, and injecting contrast material to opacify the ureter and collecting system while obtaining fluoroscopic images 1, 2
• The procedure requires fluoroscopic equipment (mobile C-arm machine), an operating room with radiation-shielded walls, and a C-arm compatible operating table 3
• The procedure can be performed using a flexible cystoscope to identify the ureteric orifice, followed by insertion of a guidewire into the renal pelvis under fluoroscopic guidance 4

Primary Indications

• Suspected ureteral injuries, particularly iatrogenic injuries during surgery 3, 1
• Evaluation of ureteral obstruction when other imaging modalities are contraindicated or insufficient 1, 4
• Identification of ureteral stones or tumors not clearly visualized by other imaging methods 1
• Assistance for ureteral stent placement or ureteroscopy 1, 4
• Trauma evaluation of the urinary tract 1, 3
• Cases where collecting system detail is deemed imperative in patients with contraindications to CT or MRI 3

Special Clinical Scenarios

• Alternative to CT in patients with contraindications: For patients with relative or absolute contraindications to multi-phasic CT (such as renal insufficiency, contrast allergy, pregnancy), combining MRI with retrograde pyelograms provides alternative evaluation of the entire upper urinary tract 3
• Intraoperative diagnosis of ureteral injuries: The gold standard for intraoperative detection of iatrogenic urinary tract injuries is diagnostic cystoscopy with retrograde pyelogram 3
• Pregnancy: In pregnant patients with suspected urinary tract issues, retrograde pyelogram combined with ultrasound may be used instead of CT to minimize radiation exposure 3

Advantages

• Provides detailed visualization of the collecting system that may not be adequately seen on cross-sectional imaging 3
• Can be performed in patients with renal insufficiency when intravenous contrast is contraindicated 2, 3
• Allows for concurrent therapeutic interventions such as stent placement 4
• Can be performed on an outpatient basis under sedoanalgesia in many cases 4

Limitations and Risks

• Invasive procedure requiring urological expertise and specialized equipment 3
• Risk of complications including infection, ureteral injury, or contrast reactions 2
• Bilateral retrograde pyelography performed simultaneously may rarely lead to acute renal shutdown, particularly in patients with pre-existing renal insufficiency 2
• Limited usefulness as a standalone diagnostic tool; often needs to be combined with other imaging modalities 5

Modern Role in Diagnostic Algorithm

• Not indicated for initial evaluation of uncomplicated conditions like pyelonephritis 3
• Has been largely replaced by CT and MRI for many diagnostic purposes 3, 5
• Still valuable in specific scenarios such as intraoperative detection of ureteral injuries or when cross-sectional imaging is contraindicated 3
• Can reveal concurrent urinary tract abnormalities that might not be visible during surgical procedures without imaging 6

Clinical Pearls

• When performing retrograde pyelography, careful attention should be paid to the volume and concentration of contrast used to avoid complications 2
• The procedure should be performed with caution if bilateral studies are contemplated, especially in patients with compromised renal function 2
• In emergency settings, direct inspection of the ureters should always be performed during laparotomy in patients with suspected ureteral injury 3
• Methylene blue or indigo carmine can be used as adjunctive measures during surgery to help identify urinary leaks 3