Karyotyping (CVS/Amniotic fluid)

Karyotyping (CVS/Amniotic Fluid) is a specialized prenatal genetic test used to analyze the number and structure of chromosomes in fetal cells. The test helps identify chromosomal abnormalities that may lead to genetic disorders, developmental abnormalities, or congenital conditions during pregnancy.

Chromosomes contain genetic material that determines how the body develops and functions. Humans normally have 46 chromosomes arranged in 23 pairs. Any extra, missing, or structurally abnormal chromosome can result in genetic conditions that may affect fetal growth and development.

The test is performed using fetal cells obtained through either:

• Chorionic Villus Sampling (CVS), usually performed between 10 and 13 weeks of pregnancy.
• Amniocentesis (Amniotic Fluid Sampling), usually performed after 15 weeks of pregnancy.

The collected fetal cells are cultured and analyzed in a cytogenetics laboratory to produce a complete chromosome profile known as a karyotype. This analysis helps detect numerical and structural chromosome abnormalities.

Karyotyping remains one of the most reliable prenatal diagnostic methods for evaluating chromosomal disorders and confirming abnormal screening results.

Benefits of the Test

• Detects chromosomal abnormalities in the fetus
• Helps diagnose genetic disorders before birth
• Supports high-risk pregnancy evaluation
• Assists in pregnancy management decisions
• Provides accurate chromosome analysis
• Supports genetic counseling and family planning

Why Doctors Recommend This Test

Doctors may recommend prenatal karyotyping when:

• Maternal age is advanced (typically 35 years or older)
• Prenatal screening tests indicate increased risk
• Ultrasound abnormalities are detected
• There is a family history of genetic disorders
• Previous pregnancies were affected by chromosomal abnormalities
• Positive non-invasive prenatal testing (NIPT) results require confirmation
• Parents carry chromosomal rearrangements

The test provides definitive chromosomal information that helps guide further clinical management.

Preparation Before Test

The test requires a fetal sample obtained through:

Chorionic Villus Sampling (CVS)

• Usually performed between 10–13 weeks of pregnancy
• Samples placental tissue containing fetal cells

Amniocentesis

• Usually performed after 15 weeks of pregnancy
• Collects amniotic fluid containing fetal cells

Preparation may include:

• Genetic counseling
• Ultrasound evaluation
• Consultation with a fetal medicine specialist
• Review of family and pregnancy history

Normal Reporting Time

Results are generally available within 10 to 21 working days, depending on cell culture growth and laboratory processing requirements.

Who Should Take This Test?

• Pregnant women with abnormal prenatal screening results
• Women of advanced maternal age
• Couples with a history of chromosomal abnormalities
• Pregnancies with abnormal ultrasound findings
• Families at increased genetic risk
• Individuals referred for prenatal genetic diagnosis

Prenatal karyotyping is considered a gold-standard diagnostic test for detecting chromosomal abnormalities during pregnancy.

Clinical Significance

The test may help diagnose:

• Down Syndrome (Trisomy 21)
• Edwards Syndrome (Trisomy 18)
• Patau Syndrome (Trisomy 13)
• Turner Syndrome
• Klinefelter Syndrome
• Sex chromosome abnormalities
• Chromosomal translocations
• Deletions and duplications
• Structural chromosome abnormalities

The results help healthcare providers offer accurate genetic counseling and make informed decisions regarding pregnancy care.