Karyotyping (Amniotic fluid/CVS) with FISH - single probe

Karyotyping (Amniotic Fluid/CVS) with FISH – Single Probe is an advanced prenatal genetic test used to evaluate the chromosome structure and number in a developing fetus. The test combines conventional karyotyping with Fluorescence In Situ Hybridization (FISH) using a single targeted probe to detect specific chromosomal abnormalities quickly and accurately.

The test is performed on samples obtained through Amniocentesis (Amniotic Fluid) or Chorionic Villus Sampling (CVS). These procedures collect fetal cells that are then analyzed in a specialized genetics laboratory.

Karyotyping provides a complete overview of all chromosomes and can identify abnormalities such as extra chromosomes, missing chromosomes, large chromosomal rearrangements, translocations, and structural abnormalities.

FISH (Fluorescence In Situ Hybridization) is a rapid molecular cytogenetic technique that uses fluorescent probes to target a specific chromosome or genetic region. A single-probe FISH analysis is typically requested when there is suspicion of a particular chromosomal condition or when confirmation of a specific abnormality is required.

This combined approach provides both rapid targeted results and a comprehensive chromosomal evaluation.

Benefits of the Test

• Detects fetal chromosomal abnormalities
• Provides early prenatal genetic information
• Combines rapid FISH results with complete karyotyping
• Helps assess high-risk pregnancies
• Supports informed pregnancy management decisions
• Assists genetic counseling and risk assessment

Why Doctors Recommend This Test

Doctors may recommend this test when:

• Prenatal screening indicates increased genetic risk
• Advanced maternal age is present
• Abnormal ultrasound findings are detected
• Family history of chromosomal disorders exists
• Previous pregnancy was affected by a chromosomal abnormality
• Confirmation of a suspected chromosome defect is required
• Positive non-invasive prenatal testing (NIPT) results need confirmation

The test helps provide accurate genetic information about the fetus and supports clinical decision-making.

Preparation Before Test

The test requires either:

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

Preparation may include:

• Consultation with a fetal medicine specialist
• Genetic counseling
• Ultrasound evaluation before the procedure
• Following instructions provided by the healthcare team

Normal Reporting Time

• FISH Single Probe Results: 1–3 working days
• Complete Karyotyping Results: 10–21 working days

Reporting time may vary depending on sample quality and laboratory protocols.

Who Should Take This Test?

• Pregnant women with high-risk screening results
• Women of advanced maternal age
• Couples with a history of chromosomal abnormalities
• Pregnancies with abnormal ultrasound findings
• Families requiring prenatal genetic diagnosis
• Patients referred by fetal medicine specialists

This test is an important prenatal diagnostic tool that helps identify chromosomal abnormalities early in pregnancy and supports informed healthcare decisions.

Clinical Significance

The test may help detect:

• Down Syndrome (Trisomy 21)
• Edwards Syndrome (Trisomy 18)
• Patau Syndrome (Trisomy 13)
• Sex chromosome abnormalities
• Structural chromosome rearrangements
• Translocations
• Deletions and duplications targeted by the selected FISH probe
• Other fetal chromosomal abnormalities