Microbiology, transfusion and tissue pathology

Where you are

Microbiology studies organisms. Transfusion services prepare and support the use of blood products. Cytopathology examines cells, while surgical pathology examines submitted tissue. In each area, the coding unit may differ from the number of containers, slides, needle passes or report lines.

This lesson follows a specimen from collection to interpretation. Your task is to identify the actual procedure, the specimen relationship and the work already included. Use the current complete entry for the final code; the examples teach the decisions that lead to it.

Start with specimen identity

Write the anatomical source and whether material was submitted for separate examination and diagnosis. A specimen label such as “biopsy” is incomplete. The report should tell you what tissue or fluid was examined, where it came from and what the laboratory did.

NCCI defines a surgical pathology specimen by individual and separate attention, examination and diagnosis. Separate containers are common, but the medically necessary specimen relationship controls. Several pieces from one polyp do not automatically become several specimens. Two separate lesions submitted for separate diagnosis can have a different relationship. [ncci-laboratory-2026, M.8]

Original fictional record: two colon polyps from different sites are separately labeled because the clinician needs to know which lesion is malignant. Compare that with three fragments from one polyp submitted together. Explain the difference before counting any units.

Match the microbiology method

Identify culture, antigen testing, nucleic acid testing or another documented method. NCCI directs selection of the most specific culture entry for the source and type of study. A commercial kit does not justify a less specific entry when the completed test is described more accurately elsewhere. [ncci-laboratory-2026, K.1]

Do not assume that culture and molecular testing are synonyms. They can produce different information. At the same time, Medicare generally does not pay twice for the same organism from the same site merely because two methods were used. Read the stated exceptions. [ncci-laboratory-2026, K.2,K.4]

One exception concerns a positive culture-independent result followed by a necessary culture for drug sensitivity testing or, rarely, surveillance identification. That clinical purpose differs from duplicating the same result with another method. The record must establish why the added work was needed. [ncci-laboratory-2026, K.4]

Reflex testing is a specific relationship

Some initial results need follow-up identification to become clinically useful. NCCI describes organism identification after a positive urine culture as a separately reportable reflex relationship implicit in the original order. Do not turn that example into permission for every possible additional test. [ncci-laboratory-2026, A]

A rerun that merely confirms the initial result is different. So is a follow-up assay that requires a separate treating-practitioner order. State which relationship exists instead of labeling all additional work “reflex.”

For multiplex infectious-agent testing, read the anatomical region, target grouping and performed method. More reported organisms do not necessarily mean more procedures. NCCI has specific instructions for combined targets and for one procedure or kit that yields several results. [ncci-laboratory-2026, K.5,M.15]

Blood products and preparation can overlap

Separate the blood product from testing, preparation and administration. A HCPCS product entry may already describe processing such as irradiation, pooling or thawing. NCCI prohibits separately adding the same included processing to those specified products. [ncci-laboratory-2026, J]

Original fictional example: a supplied product is represented by an entry that includes irradiation. The preparation record confirms irradiation occurred. That does not support adding another irradiation service to the already inclusive product. First read the complete product definition, then review any truly separate work.

Do not use the product rule to infer that every transfusion-related service is included. Compatibility testing, product supply and administration require their own complete entries and payer instructions. Your worksheet should identify each actual activity and its relationship to the product.

Gross and microscopic work can be one service

Gross examination describes what can be assessed without the microscope; microscopic examination studies prepared material under magnification. NCCI includes gross examination in the specified gross-and-microscopic surgical pathology services. Do not add a gross-only entry for the same specimen. [ncci-laboratory-2026, L.9]

The surgical pathology level must match the current listed specimen and service. Do not infer a higher level merely from malignancy, specimen size or the length of the report. Read the complete specimen list in your licensed book and any applicable payer exception.

Medicare has a specific reporting rule for submitted prostate needle biopsy specimens from one patient. It uses the specified HCPCS service with one unit rather than applying the ordinary CPT specimen entry independently to each core. Keep that payer instruction separate from general specimen counting. [ncci-laboratory-2026, L.10]

Cytology uses its own preparation rules

For one cytology specimen, NCCI generally permits one entry from the related preparation and examination group with the same end result. Smears already included in the applicable fluid, washing or brushing service do not create another service through an “other source” entry. [ncci-laboratory-2026, L.1]

Separate anatomical sites may support distinct services when the report documents the relationship and the full rules permit it. A modifier explains supported distinct work; it does not create distinct specimens from duplicate preparations.

Count adequacy episodes, not needle passes

During a fine-needle aspiration, the pathologist may assess whether material is adequate for diagnosis. NCCI defines the relevant evaluation episode around the assessment communicated to the operating clinician. Several passes examined before that decision can remain one episode. [ncci-laboratory-2026, M.7]

A further episode requires the completed assessment and a decision to obtain more material. Build a timeline: material submitted, assessment delivered, clinician's decision and further sampling. Do not count slides or passes as a substitute for that sequence.

Special stains have specific units

For the cited special stains, staining several levels from the same tissue block with the same stain does not produce extra units. Medically necessary application to another block or specimen has its own review. Controls do not become separately billed patient stains. [ncci-laboratory-2026, M.9]

Immunohistochemistry has a different unit structure based on the stain procedure and specimen. A cocktail yielding one result is not automatically a multiplex service with several separately interpretable results. Read the exact method and output before counting. [ncci-laboratory-2026, M.9–10]

Book drill

Trace a culture through identification, a blood product through included preparation and a tissue specimen through gross and microscopic examination. For each, write the actual unit beside the procedure.

Checkpoint

Check the specimen and unit

Separate lesion specimens differ from fragments of one lesion. A product can include its preparation. One cytology preparation, one adequacy episode and one stain unit have different definitions. Count the documented work using the applicable entry rather than the number of slides or report lines.

Sources

1. CMS — Medicare NCCI 2026 Chapter X: Pathology and Laboratory. 2026. Accessed 2026-09-10.