Chromosome Analysis
Test Description
Chromosome analysis involves the study of an individual’s chromosomal makeup,
or karyotype. Both chromosomal number and structure are studied. The test is used
to determine chromosomal abnormalities and to identify the child’s sex in the case
of ambiguous genitalia or prior to delivery. This test is considered part of the workup
done for amenorrhea, infertility, and frequent miscarriages. It is also used in genetic
counseling for individuals with a family history of genetic disease. Chromosome
analysis usually involves a culture of leukocytes from peripheral blood. However,
karyotyping may also be completed on other tissues, including amniotic fluid, bone
marrow, buccal smear, chorionic villus, placental tissue, skin, and tumor cells.
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Normal Values
Female: 44 autosomes, plus 2 X chromosomes; Karyotype: 46, XX
Male: 44 autosomes, plus 1X, 1Y chromosome; Karyotype: 46, XY
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Possible Meanings of Abnormal Values
Ambiguous genitalia
Down syndrome
Hyperploidy (>46 chromosomes)
Hypogonadism
Hypoploidy (<46 chromosomes)
Kleinfelter’s syndrome
Mental retardation
Physical retardation
Trisomy 18
Turner’s syndrome
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Contributing Factors to Abnormal Values
• Hemolysis of the blood sample will alter test results.
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Interventions/Implications
Pretest
• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.
• No fasting is required before the test.
Procedure
• A 7-mL blood sample is drawn in a green-top (heparinized) collection tube.
• Gloves are worn throughout the procedure.
Posttest
• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued
bleeding.
• Label the specimen and transport it to the laboratory.
• Report abnormal findings to the primary care provider.
of ambiguous genitalia or prior to delivery. This test is considered part of the workup
done for amenorrhea, infertility, and frequent miscarriages. It is also used in genetic
counseling for individuals with a family history of genetic disease. Chromosome
analysis usually involves a culture of leukocytes from peripheral blood. However,
karyotyping may also be completed on other tissues, including amniotic fluid, bone
marrow, buccal smear, chorionic villus, placental tissue, skin, and tumor cells.
ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ
Clinical Alerts
• Provide emotional support throughout the test and during the period of time
spent waiting for results (time varies depending on type of tissue to be analyzed).
• Make appropriate referrals for genetic counseling, as needed.
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