CPT code 50431: Antegrade contrast study, new access2026 Medicare rate & RVUs

Medicare pays $307.96 for 50431 nationally in the office and $59.12 in a hospital or facility. Local office rates run $268.19–$428.58.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

What 50431 covers

An antegrade nephrostogram or ureterogram traces contrast from the kidney’s collecting system down the ureter. Code 50431 identifies a diagnostic study reached by creating new percutaneous access, rather than injecting contrast through an already-present nephrostomy catheter. An interventional radiologist or urologist typically uses ultrasound or fluoroscopy to guide access, injects contrast, and interprets the images in an interventional radiology suite or hospital procedure room. The study can help clarify suspected obstruction, a leak, or impaired drainage.

Report 50431 when the new access is used for the contrast examination and a catheter placement service does not account for the work. Nephrostomy or nephroureteral catheter placement codes include the diagnostic contrast study when performed, so do not separately report 50431 for that included imaging. Document the indication, newly obtained access, contrast examination, findings, and laterality. CMS assigns a 0-day global period, including same-day preoperative and postoperative care. For bilateral service, modifier 50 is paid at 150%. In a session with multiple procedures, the highest-valued procedure is paid in full and others at 50%. Assistant-at-surgery payment is barred; co-surgeon and team-surgery billing are not permitted.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 50431 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

50431 rates by state

Office rate range in each state. Select a state to see its payment localities.

How the 50431 rate is calculated

Each of 50431’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

Payment rules and modifiers for 50431

The CMS indicators that decide how 50431 is paid alongside other services.

What modifiers do to the payment

When to use modifier 50

50431 compared with similar codes

How to choose

50430Antegrade nephrostogramExisting access

Choose 50431 when the contrast study requires new percutaneous access. Choose 50430 when contrast is injected through existing access.

50432Nephrostomy placementNew percutaneous access

50432 covers percutaneous nephrostomy catheter placement, including the diagnostic contrast study when performed. 50431 is for the contrast study through new access when catheter placement is not the service reported.

50433Catheter placementNephroureteral catheter

50433 covers nephroureteral catheter placement, including the diagnostic contrast study when performed. 50431 describes the new-access contrast study without that catheter placement service.

Codes related to 50431

Related codes aren’t interchangeable: bill the code that matches the service performed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Open CMS sourceHow we calculate rates