CPT code 88121: Urine FISH, computer-assisted, 3–5 probes2026 Medicare rate & RVUs

Medicare pays $393.80 for 88121 nationally in the office. Local office rates run $342.43–$555.78.

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

What 88121 covers

88121 represents computer-assisted cytopathologic analysis of a urinary tract specimen using in situ hybridization with a panel of three to five probes. The method evaluates probe signals in urothelial cells for chromosomal changes associated with urothelial carcinoma; it may be used when evaluating hematuria or monitoring a patient with a history of bladder cancer. Laboratory staff prepare and analyze the specimen, with a pathologist or other qualified professional interpreting the findings. Pathology and molecular diagnostic laboratories commonly perform this service.

Report one unit for each specimen examined. Documentation should identify the urinary specimen, the probe panel and count, the computer-assisted method, and the interpretation. This distinguishes 88121 from 88120, which describes the corresponding service without computer assistance. CMS recognizes professional and technical components: modifier 26 identifies interpretation, modifier TC identifies equipment and staff, and billing without either modifier represents the global service.

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 88121 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

88121 rates by state

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

How the 88121 rate is calculated

Each of 88121’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 88121

The CMS indicators that decide how 88121 is paid alongside other services.

What modifiers do to the payment

When to use modifier 26

88121 compared with similar codes

How to choose

88120Urine FISHThree to five probes

Choose 88121 when the urinary in situ hybridization analysis is computer-assisted. 88120 describes the corresponding three-to-five-probe service without computer assistance.

88112Selective-enhancement cytologyNongynecologic specimens

88112 is a cell-enhanced cytology examination focused on cell morphology. 88121 is a probe-based molecular analysis of a urinary tract specimen.

88104Fluid cytologyDirect smear method

88104 reports morphologic examination of a fluid or washing smear. 88121 reports computer-assisted in situ hybridization with three to five probes.

Codes related to 88121

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