Pathology/Lab Coding Alert

Differentiate molecular test codes.

The current focus on explosive growth in molecular pathology testing can take your head out of the game when faced with coding some old-fashioned cytogenetic tests.

In fact, you need to make sure you’re familiar with codes 88230-88299 in the CPT^® Cytogenetic Studies section when your lab performs microscopic chromosome studies to identify changes associated with inherited or acquired conditions such as certain cancers or congenital syndromes.

Spotlight: “The focus of cytogenetic studies is cells, and specifically, the chromosomes contained within those cells,” says William Dettwyler, MT AMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore. The procedures involve microscopically evaluating characteristics such as additions or deletions to a chromosome, visible bands within chromosomes, or visually-targeted markers within chromosomes.

Make sure to distinguish this type of testing from molecular pathology analyses that focus on evaluating sequences of nucleic acids (DNA and RNA). Read on to learn more about the procedures, purposes, and codes involved in the Cytogenetic Studies section.

Grasp Preparation Codes

Before the lab analyst can evaluate chromosomes under the microscope, she may need to perform several steps to acquire enough cellular material for the studies, and to manipulate the material to prepare it for a cytogenetic test. That’s what the first seven codes in this CPT^® section are for, as follows:

• 88230-88235 — Tissue culture for non-neoplastic disorders …

• 88237-88239 — Tissue culture for neoplastic disorders …

• 88240 — Cryopreservation, freezing and storage of cells, each cell line

• 88241 — Thawing and expansion of frozen cells, each aliquot.

Unpack Chromosome Analysis

Most of the codes in the Cytogenetic Studies section deal with chromosome analysis. This involves preparing the cells using certain types of stains, and evaluating the chromosomes under the microscope. In the examination, the lab analyst can observe chromosome changes that might indicate an abnormality of clinical significance. The variations might involve a change in chromosome number, called aneuploidy (normal is 23 chromosome pairs), breakage, additions or deletions of part of a chromosome, and patterns of visible “bands” in the stained chromosomes. This pattern of visualized and counted chromosomes within a cell is called a karyotype.

Generally, each cell in the body (except reproductive cells) would have a similar karyotype, but that is not always true. Sometimes a change will occur in a cell, which continues to divide and grow, perpetuating a cell line that is different than other cells within the body. This condition is called “mosaicism,” and is an important factor in determining which cells, and how many cells, the analyst must evaluate to ensure that the study will find any chromosomal abnormalities present.

The differences between chromosome analysis codes focus on factors such as the number of cells counted, the number of karyotypes, the cell source, and the type of staining and banding, as follows:

• 88245-88249 — Chromosome analysis for breakage syndromes …

The type of breakage analysis and the number of karyotypes and cells counted and scored distinguish these three codes. 

• 88261-88264 — Chromosome analysis … 

Each of the unique codes in this range specifies the number of karyotypes with banding, and the number of cells in which the analyst counts chromosome number. The codes range from five cells with one karyotype with banding (88261) to 45 cells with two karyotypes with banding (88263).

• 88267-88269 — Chromosome analysis … amniotic fluid... 

These two codes describe distinct analyses for fetal evaluation.

• 88280-88289 — Chromosome analysis …

Use these four codes for additional chromosomal studies, such as additional karyotype studies (88280), additional specialized banding methods (88283), additional cell-counting studies (88285), and additional high resolution study (88289). Although these are not CPT® add-on codes, you would expect to use these codes in addition to a separate code for an initial chromosome analysis.

Meet the ISH Codes

Another tool the lab analyst may use to evaluate chromosomes under the microscope involves “hybridizing” the chromosomes with labeled probes that the analyst can then visualize. The probes are typically nucleic acid sequences with a label, such as a fluorescent dye, that selectively attaches to a nucleic acid sequence in the chromosome in a process called hybridization. The lab analyst can then visualize where the probes attached to the chromosome, and evaluate the chromosome for specific abnormalities. The process is called “in situ hybridization” (ISH), or if using a fluorescent label, “fluorescence in situ hybridization (FISH).

The cytogenetic ISH codes are as follows:

• 88271 — Molecular cytogenetics; DNA probe, each (e.g., FISH)

• 88272 — … chromosomal in situ hybridization, analyze 3-5 cells (e.g., for derivatives and markers)

• 88273 — …chromosomal in situ hybridization, analyze 10-30 cells (e.g., for microdeletions)

• 88274 — … interphase in situ hybridization, analyze 25-99 cells

• 88275 — … interphase in situ hybridization, analyze 100-300 cells

Medical professionals order these tests to detect specific genes (including amplification or translocation), or oncogenes, or to identify chromosomes and chromosome aneuploidy. The studies represent fluorescent, enzyme, or other labels on ISH DNA probes that hybridize with specific sequences in or on interphase cell nuclei or metaphase chromosomes following cell culture and spread preparation.

Unit of service varies: Molecular cytogenetics codes for cellular ISH are “building block” codes. You should select the appropriate hybridization code (88272-88275) based on the number of cells analyzed and whether the lab used metaphase or interphase hybridization. In addition to the hybridization, a single ISH study might involve multiple DNA probes, and you should report one unit of 88271 for each probe.

Beware bundling issues: Medicare’s Correct Coding Initiative (CCI) bundles 88274 as a column 2 code with 88275, and 88272 as a column 2 code with 88273. That means the codes don’t “add up” (such as 88372 for the first five cells, plus 88273 for the next 10 cells in a test that evaluates 15 cells). Instead, you should select the single code that describes the single test for the appropriate number of cells (88273 for 15 cells because that’s in the range of 10-30 cells).

Exception: But what if the lab examines interphase cell nuclei from two separate cell cultures to detect different genes or chromosomes? “If one of the molecular cytogenetics studies involves 25-99 cells, and the other involves 100-300 cells, you can report both 88275 and 88274 using modifier 59 (Distinct procedural service) or other appropriate modifier,” says Peggy Slagle, CPC, coding and compliance manager for the department of pathology/microbiology at the University of Nebraska Medical Center in Omaha. Because the work involves two separate analyses and CCI lists codes 88275 and 88274 with a modifier indicator of “1,” you can bill for both tests on the same day.

Don’t confuse tissue ISH: Codes 88271-88275 aren’t the only CPT^® codes for ISH. You’ll also find codes 88365-88377 for ISH procedures in the Surgical Pathology section. When a pathologist performs in situ hybridization techniques as an adjunct to a surgical pathology or cytopathology case, you should use the appropriate codes from the range 88365 to 88377. But when the lab performs in situ hybridization as an ancillary analysis to cytogenetic studies for oncologic or inherited disorders, you should use the 88271-88275 codes.

Capture Interpretation Service

Although the codes in the Cytogenetic Studies section are primarily technical codes paid on the Clinical Laboratory Fee Schedule (CLFS), a pathologist may additionally provide an interpretation and report on the findings of the cytogenetic tests. If this occurs, the pathologist can bill 88291 (Cytogenetics and molecular cytogenetics, interpretation and report) for the interpretation and report. CMS pays for this code on the Physician Fee Schedule, so you shouldn’t use the code to report the work of a PhD clinical laboratory professional.

Caution: CMS considers 88291 to represent the interpretation and report of “all cytogenetic/molecular cytogenetic testing performed on a single date of service,” so you should report only one unit of 88291 for a single patient on a single day, regardless of the number of cytogenetic studies evaluated.