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In situ hybridization (FISH) is a specialized laboratory technique utilized to identify and localize specific nucleic acid sequences, including DNA and RNA, within fixed tissue samples or cells. This method provides critical temporal and spatial information regarding gene expression and genetic coding, which is essential for understanding the organization, regulation, and functional roles of genes within biological systems. The process begins with the fixation of sample cells or tissues to preserve the target transcripts in their original locations. Following fixation, a DNA or RNA probe is introduced, which hybridizes, or binds, to the target nucleic acid sequence at an elevated temperature. After hybridization, any unbound excess probe is washed away, leaving only the bound probes attached to the target sequences. The remaining DNA or RNA targets are then stained using spectrally distinct fluorophore labels, allowing for visualization under fluorescent microscopy. This technique is particularly valuable in genetic analysis, as DNA-FISH can reveal the presence, copy number, and location of genes, while RNA-FISH can provide insights into gene expression and the temporal and spatial localization of RNA within the specimen. The FISH technique is versatile, enabling the simultaneous use of multiple probes to visualize co-locations of different targets within a single specimen. In the context of coding, CPT® Code 88365 is designated for the initial single probe stain per specimen, while CPT® Code 88364 is specifically used for each additional single probe stain performed, and CPT® Code 88366 is applicable when multiple probes are utilized in the same staining procedure.
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The in situ hybridization (FISH) technique is indicated for various diagnostic and research purposes, particularly in the following scenarios:
The in situ hybridization (FISH) procedure involves several critical steps to ensure accurate localization and visualization of nucleic acid targets:
After the completion of the in situ hybridization (FISH) procedure, careful analysis of the results is conducted. The expected outcomes include clear visualization of the target nucleic acids, which can be documented for further interpretation. It is important to ensure that the fluorescent signals are distinct and interpretable, as this will impact the accuracy of the findings. Additionally, any necessary follow-up procedures or confirmatory tests may be recommended based on the results obtained. Proper documentation of the procedure, including the types of probes used and the results of the analysis, is essential for compliance and future reference. The recovery of the samples is typically straightforward, as the procedure is performed on fixed tissues, and no invasive techniques are involved.
| Short Descr | INSITU HYBRIDIZATION (FISH) | Medium Descr | IN SITU HYBRIDIZATION EA ADDL PROBE STAIN | Long Descr | In situ hybridization (eg, FISH), per specimen; each additional single probe stain procedure (List separately in addition to code for primary procedure) | Status Code | Active Code | Global Days | ZZZ - Code Related to Another Service | PC/TC Indicator (26, TC) | 1 - Diagnostic Tests for Radiology Services | Multiple Procedures (51) | 0 - No payment adjustment rules for multiple procedures apply. | Bilateral Surgery (50) | 0 - 150% payment adjustment for bilateral procedures does NOT apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 0 - Payment restriction for assistants at surgery applies to this procedure... | Co-Surgeons (62) | 0 - Co-surgeons not permitted for this procedure. | Team Surgery (66) | 0 - Team surgeons not permitted for this procedure. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | APC Status Indicator | Items and Services Packaged into APC Rates | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | T1G - Lab tests - other (Medicare fee schedule) | MUE | 3 |
This is an add-on code that must be used in conjunction with one of these primary codes.
| 88365 | MPFS Status: Active Code APC Q1 PUB 100 CPT Assistant Article In situ hybridization (eg, FISH), per specimen; initial single probe stain procedure | 0849T | Add On Code Resequenced Code MPFS Status: Carrier Priced APC N Digitization of glass microscope slides for in situ hybridization (eg, FISH), per specimen; each additional single probe stain procedure (List separately in addition to code for primary procedure) |
| 26 | Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number. | TC | Technical component; under certain circumstances, a charge may be made for the technical component alone; under those circumstances the technical component charge is identified by adding modifier 'tc' to the usual procedure number; technical component charges are institutional charges and not billed separately by physicians; however, portable x-ray suppliers only bill for technical component and should utilize modifier tc; the charge data from portable x-ray suppliers will then be used to build customary and prevailing profiles | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | GC | This service has been performed in part by a resident under the direction of a teaching physician | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service | XE | Separate encounter, a service that is distinct because it occurred during a separate encounter | Q1 | Routine clinical service provided in a clinical research study that is in an approved clinical research study | AQ | Physician providing a service in an unlisted health professional shortage area (hpsa) | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure | X5 | Diagnostic services requested by another clinician: for reporting services by a clinician who furnishes care to the patient only as requested by another clinician or subsequent and related services requested by another clinician; this modifier is reported for patient relationships that may not be adequately captured by the above alternative categories; reporting clinician service examples include but are not limited to, the radiologist's interpretation of an imaging study requested by another clinician | 56 | Preoperative management only: when 1 physician or other qualified health care professional performed the preoperative care and evaluation and another performed the surgical procedure, the preoperative component may be identified by adding modifier 56 to the usual procedure number. | 76 | Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service. | 77 | Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service. | 90 | Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number. | 91 | Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient. | CC | Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed) | CR | Catastrophe/disaster related | GA | Waiver of liability statement issued as required by payer policy, individual case | GV | Attending physician not employed or paid under arrangement by the patient's hospice provider | GW | Service not related to the hospice patient's terminal condition | GZ | Item or service expected to be denied as not reasonable and necessary | Q0 | Investigational clinical service provided in a clinical research study that is in an approved clinical research study | Q5 | Service furnished under a reciprocal billing arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area | Q6 | Service furnished under a fee-for-time compensation arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area | XP | Separate practitioner, a service that is distinct because it was performed by a different practitioner |
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| 2024-01-01 | Changed | Guideline added. |
| 2015-01-01 | Added | Added |
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