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Cytogenetics

Verify PHI & Test Orders

The pre-analytical phase of testing is the most common source of laboratory error. In Clinical Cytogenetics, the consequences of a labeling error or an incorrect test order are profound, potentially leading to the termination of a healthy pregnancy, an incorrect cancer diagnosis, or inappropriate chemotherapy. Therefore, the process of accessioning - receiving the sample and entering it into the Laboratory Information System (LIS) - is not merely clerical. It is a critical control point where the laboratory scientist serves as the gatekeeper of patient safety, ensuring that the specimen, the patient identity, and the clinical intent are perfectly aligned

Patient Identification Criteria

Regulatory standards (such as those from CLIA and CAP) mandate strict adherence to patient identification protocols. The laboratory must verify that the physical specimen belongs to the patient described on the accompanying paperwork. This verification process relies on the presence of at least two unique patient identifiers

  • The Two-Identifier Rule: Every specimen container and every requisition form must contain two distinct pieces of information that uniquely identify the patient. Common acceptable identifiers include:
    • Patient’s Full Name (First and Last)
    • Date of Birth (DOB)
    • Medical Record Number (MRN) or Hospital ID
    • Social Security Number (less common now due to privacy concerns)
  • Unacceptable Identifiers: Data that can change or is not unique to the patient cannot be used as a primary identifier. Examples include the patient’s room number, bed number, or the name of the attending physician
  • The Match: The information on the specimen label must match the requisition form exactly. A discrepancy as minor as a spelling variation (“Jon” vs. “Jonathan”) or a transposed digit in the DOB requires resolution before testing can proceed. The laboratory scientist cannot “assume” identity

Requisition Review & Data Entry

The requisition form provides the roadmap for the analysis. The laboratory scientist must verify that all necessary data points are present to ensure the test is performed, interpreted, and billed correctly. Missing information often triggers a “hold” on the specimen

  • Demographic Information
    • Biological Sex: This is critical in cytogenetics. The analysis of sex chromosomes (XX vs. XY) depends on knowing the phenotypic sex of the patient. For example, finding a 46,XY karyotype is normal for a male but represents Androgen Insensitivity Syndrome or a sample mix-up in a female
    • Date of Birth: Essential for determining “age-related risk” in prenatal cases or distinguishing constitutional anomalies from acquired changes in elderly populations
  • Specimen Information
    • Date and Time of Collection: Crucial for assessing viability. A blood sample collected 5 days ago may require different culture stimulation techniques than one collected 2 hours ago
    • Collection Site: The requisition must specify the source (e.g., “Right Iliac Crest” vs. “Peripheral Blood”). This determines the culture media and mitogens used. If the requisition says “Blood” but the tube looks like marrow, the lab must call to verify
  • Ordering Physician: The name and contact information of the provider must be legible to ensure the critical results (e.g., a diagnosis of Acute Promyelocytic Leukemia) can be called in immediately

Clinical Validity & Test Appropriateness

The laboratory scientist is responsible for ensuring the ordered test makes sense in the context of the clinical indication (diagnosis). A mismatch between the “Indication” and the “Test Ordered” often signals a clerical error by the ordering provider

  • Constitutional vs. Acquired
    • Scenario: A doctor orders a “Chromosome Analysis” on peripheral blood for a 70-year-old patient with a high white count, but does not specify “Leukemia.”
    • The Catch: Routine blood karyotypes use a T-cell mitogen (PHA). If the patient has leukemia, the lab needs to analyze the spontaneous division of blasts, not T-cells. If the lab adds PHA based on a standard “blood” order, they might miss the leukemia. The laboratory scientist must notice the age and WBC count and clarify if the doctor wants a “Leukemia Blood Study” (unstimulated) or a “Constitutional Study” (stimulated)
  • FISH vs. Karyotype
    • Clinicians often use loose terminology. An order for “Genetics for Down Syndrome” could mean a rapid FISH panel or a full Karyotype. The laboratory scientist must verify the intent. If a full structural analysis is needed to rule out translocation Down Syndrome (heritable), a FISH test alone is insufficient
  • Specimen Type Compatibility
    • Verifying that the specimen type is appropriate for the test. For example, if a physician orders “Products of Conception (POC) Karyotype” but sends a tube of maternal blood, the order is invalid. The blood will yield the mother’s karyotype, not the fetus’s

Handling Discrepancies & Unlabeled Specimens

When verification fails, the laboratory must follow a strict “Rejection or Correction” protocol. The severity of the discrepancy dictates the action

  • Minor Discrepancies (Clerical): If the name is correct but the date of collection is missing, or the ordering physician’s pager number is wrong, the lab can typically call the clinic, obtain the information verbally, and document the correction in the LIS (e.g., “Per John Smith RN @ 1400 hrs…”)
  • Major Discrepancies (Identity): If the name on the tube does not match the name on the paperwork, the specimen is generally rejected. Testing an uncertain patient carries too high a liability risk
  • Unlabeled / Irretrievable Specimens
    • An unlabeled tube of blood can be redrawn easily; it is usually rejected outright
    • Irretrievable Specimens: Specimens obtained via invasive procedures (Bone Marrow, Amniotic Fluid, Tissue Biopsy) cannot be easily redrawn. If these arrive unlabeled or with major discrepancies, most labs invoke an “Irretrievable Specimen Protocol.” This requires the responsible physician to come to the laboratory, visually identify the specimen, and sign a waiver assuming full legal responsibility for the specimen’s identity. The final report will carry a permanent disclaimer stating the identification issue

Regulatory & Ethical Compliance

  • Informed Consent: In many jurisdictions, genetic testing requires specific informed consent separate from general treatment consent. The lab must verify if this documentation is required and present
  • HIPAA: During the verification process, patient privacy must be maintained. Requisitions should not be left in public view, and verification calls should be made from private areas
  • Hold Protocols: If a discrepancy cannot be resolved immediately (e.g., the clinic is closed), the specimen must be processed/stabilized (placed in media or culture) but not harvested or reported until the paperwork is resolved. This preserves the cells while the administrative issues are fixed