CPT code 88312: Special stain, group I, microorganisms2026 Medicare rate & RVUs

Medicare pays $109.55 for 88312 nationally in the office. Local office rates run $96.26–$151.19.

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

What 88312 covers

A Group I special stain helps a pathologist identify microorganisms in tissue when routine H&E examination is insufficient. Examples include Gram stain for bacteria, acid-fast stains for mycobacteria, and GMS for fungi. Giemsa or Warthin-Starry may be used to evaluate a gastric biopsy for Helicobacter pylori. Histology staff prepare the stained sections, and a pathologist interprets and reports the findings, commonly alongside a surgical pathology examination. The work may be performed in an independent laboratory or hospital pathology department.

Report one unit for each stain on each separate specimen, rather than for each block, section, or slide. Additional slides or repeats of the same stain on the same specimen do not create additional units. Documentation should identify the specimen, each stain performed, and its interpretation. Modifier TC identifies the staining work, including staff, supplies, and equipment; modifier 26 identifies the pathologist's interpretation. When one billing entity provides both components, report the global service without either component modifier.

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 88312 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

88312 rates by state

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

How the 88312 rate is calculated

Each of 88312’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 88312

The CMS indicators that decide how 88312 is paid alongside other services.

What modifiers do to the payment

When to use modifier 26

88312 compared with similar codes

How to choose

88313Special stainGroup II, tissue constituents

Use 88312 for a histochemical stain intended to identify microorganisms. Use 88313 when the stain evaluates a non-organism feature, such as iron deposits or tissue fibers; the purpose matters for stains such as PAS.

88342Antibody stainFirst single antibody per specimen

88342 reports immunohistochemical staining with a first antibody, which may detect an organism antigen. 88312 reports a histochemical stain for microorganisms without an antibody.

88305Tissue pathology examLevel IV specimen

88305 reports the surgical pathology examination of a qualifying specimen, such as a gastric biopsy. A separately performed and interpreted Group I organism stain on that specimen is reported with 88312.

Codes related to 88312

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