Name of the Procedure:

In Situ Hybridization (ISH) — Fluorescence In Situ Hybridization (FISH), per specimen; each additional single probe stain procedure (List separately in addition to code for primary procedure).

Summary

In situ hybridization (ISH) is a laboratory technique used to detect specific DNA or RNA sequences in a tissue sample by using a complementary strand of nucleic acid that binds to the target sequence. Fluorescence In Situ Hybridization (FISH) is a type of ISH where fluorescent probes are used, allowing the specific sequences to be visualized under a fluorescence microscope.

Purpose

The purpose of ISH, and specifically FISH, is to diagnose genetic abnormalities, infections, and cancers by detecting specific DNA or RNA sequences in cells and tissues. The goal is to identify the presence or absence of particular genes or genetic changes that can inform diagnosis, prognosis, and treatment strategies.

Indications

• Diagnosing genetic disorders and chromosomal abnormalities.
• Identifying specific infections (e.g., viral or bacterial).
• Detecting gene expression in cancer diagnosis and monitoring.
• Assessing genetic markers for targeted cancer therapies.
• Patients exhibiting symptoms of genetic diseases or malignancies.

Preparation

• No special preparation is typically required for the patient, as the procedure is performed on tissue samples already collected.
• Ensure that tissue specimens are properly preserved and prepared according to laboratory standards.

Procedure Description

1. Tissue sample preparation, which involves slicing the sample into thin sections.
2. Application of the fluorescent probe, which binds to the specific DNA/RNA sequence in the sample.
3. Washing away unbound probes to reduce background fluorescence.
4. Examination under a fluorescence microscope to visualize and analyze the hybridization signals.

Tools and equipment include:

• Fluorescently labeled probes (complementary DNA/RNA strands).
• Fluorescence microscope.
• Tissue slicer/microtome and glass slides.

Anesthesia or sedation is not required, as this is a laboratory test performed on collected samples.

Duration

The duration of the ISH/FISH procedure from sample preparation to results analysis typically takes several hours to a couple of days, depending on the complexity of the test and laboratory workflow.

Setting

The procedure is performed in a specialized pathology or molecular biology laboratory.

Personnel

• Pathologists or molecular biologists conducting and interpreting the test.
• Medical laboratory technologists preparing and processing the samples.

Risks and Complications

• Minimal risk associated with the procedure itself as it is conducted on tissue samples.
• Rarely, inaccurate results due to technical errors or poor sample quality.
• Misinterpretation of results can occur, needing further follow-up tests.

Benefits

• Precise detection of genetic abnormalities or infections at a molecular level.
• Helps in accurate diagnosis and personalized treatment planning.
• Can be used to monitor the effectiveness of treatment over time.

Recovery

• No recovery period necessary for the patient as it is a sample-based test.
• Follow-up includes receiving and discussing the results with the healthcare provider.

Alternatives

• Polymerase Chain Reaction (PCR) for DNA/RNA analysis.
• Immunohistochemistry (IHC) for protein detection in cells.
• Comparative Genomic Hybridization (CGH) for chromosomal anomaly detection.

Advantages and disadvantages vary:

• PCR is highly sensitive but not visually based.
• IHC detects proteins, not nucleic acids, so it has a different diagnostic use.
• CGH can screen the entire genome but may lack the specificity of FISH.

Patient Experience

• No direct patient involvement during the procedure since it works with pre-collected samples.
• Patients might experience anxiety while waiting for results.
• Healthcare providers will manage pain and discomfort related to initial tissue collection procedures if necessary.