CPT code 50391: Renal instillation, through nephrostomy access2026 Medicare rate & RVUs in Michigan
Reports delivery of a therapeutic agent into the renal pelvis or ureter through nephrostomy access, with radiologic supervision and interpretation included.
Medicare pays $123.47–$130.82 for 50391 in the office in Michigan, from Rest of Michigan to Detroit, MI. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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What 50391 covers
This service delivers a therapeutic agent into the renal pelvis or ureter through an established nephrostomy or nephroureteral catheter. A urologist or interventional radiologist may perform it when medication or a chemolytic solution is needed in the upper urinary tract, such as treatment intended to dissolve selected urinary stones. It may occur in a hospital or an appropriately equipped outpatient setting. Radiologic supervision and interpretation are part of the service.
Report the code when the documented treatment is instillation through the specified catheter route, rather than needle aspiration or injection of a renal cyst or pelvis. The record should identify the agent, treatment purpose, access route, and radiologic work. The service has a 0-day global period, so same-day preoperative and postoperative care is included. When multiple procedures occur in one session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. For bilateral performance, modifier 50 is paid at 150%. Assistant-at-surgery payment is restricted; co-surgeons and team surgery 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 50391 pays more and less in Michigan
| Payment locality | Office | Facility |
|---|---|---|
| Detroit, MI | $130.82 | $89.88 |
| Rest of Michigan | $123.47 | $84.74 |
How the 50391 rate is calculated
Each of 50391’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.
How the rate is built · 50391
RVUs × geographic indexes × conversion factor
Work1.91
1.91 RVUs× 1.000 GPCI
Practice expense1.66
1.66 RVUs× 1.000 GPCI
Malpractice0.24
0.24 RVUs× 1.000 GPCI
Adjusted RVUs
3.8100
Conversion factor
$33.4009
Medicare rate
$127.26
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 50391
The CMS indicators that decide how 50391 is paid alongside other services.
CMS payment indicators · 50391
Renal instillation, through nephrostomy access
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 000 | Same-day global: pre- and post-op care on the day of the procedure is included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| Bilateral (modifier 50) | 1 | Bilateral with modifier 50 pays 150% of the fee schedule amount. |
| Assistant at surgery (80/81/82/AS) | 1 | Not paid (statutory restriction). |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
What modifiers do to the payment
Modifier 50 · payment effect
With and without the modifier
50391 without 50 · national office
$127.26
Renal instillation, through nephrostomy access
50391-50 · Bilateral: 150%
$190.89
Both sides on one line with modifier 50 are paid at 150% of the fee schedule amount (subject to multiple-procedure rules with other procedures).
50391 compared with similar codes
Compare codes · National
50391 vs 50390: Medicare rates
How to choose
- 50390Renal lesion drainageNeedle aspiration or injection
- 50390 concerns needle aspiration or injection of a renal cyst or pelvis. Choose 50391 when the therapeutic agent is delivered through nephrostomy or nephroureteral catheter access.
50391 billing questions
When should this code be used instead of 50390?
Use 50391 for therapeutic delivery through a nephrostomy or nephroureteral catheter. Code 50390 describes percutaneous needle aspiration or injection of a renal cyst or pelvis.
Is radiologic supervision and interpretation separately reported?
No. Radiologic supervision and interpretation are included in this service.
What documentation supports the service?
Document the therapeutic agent, the clinical purpose, delivery through nephrostomy or nephroureteral access, and the associated radiologic work.
How is bilateral performance reported?
CMS identifies this as a bilateral procedure; modifier 50 is paid at 150%.
Can an assistant or co-surgeon be reported?
Assistant-at-surgery payment is restricted. Co-surgeons and team surgery are not permitted for this service.
How does the 0-day global period affect same-day care?
Same-day preoperative and postoperative care is included in the procedure's 0-day global period.
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
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