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Screening for and Diagnosing Chromosomal Abnormalities

  • Cynthia M. Johnson, MA
Publication Type:

Condition InDepth

Screening for and Diagnosing Chromosomal Abnormalities

The purpose of screening is early diagnosis and treatment. Screening tests are usually given to people who do not have current symptoms, but who may be at high risk for certain health problems.

There are many tests that look for chromosomal abnormalities. There is no cure, but the tests can help people make future health decisions. It can also help them prepare for the care the baby will need. Testing may be:

Maternal Blood Screening

The pregnant person's blood will be sampled at 15 to 18 weeks of pregnancy. It will be tested for substances that can point to a chromosomal problem in the baby. It does not mean that there is a problem. It only suggests that there is a higher risk.

If the levels are abnormal, more tests may be done to get more information. The pregnant person may need an ultrasound and amniocentesis.


  • About Turner syndrome. National Genome Research Institute website. Available at: https://www.genome.gov/Genetic-Disorders/Turner-Syndrome. Accessed May 11, 2022.
  • Chromosome abnormalities fact sheet. National Human Genome Research Institute website. Available at: https://www.genome.gov/about-genomics/fact-sheets/Chromosome-Abnormalities-Fact-Sheet. Accessed May 11, 2022.
  • Down syndrome. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/down-syndrome. Accessed May 11, 2022.


  • Kari Kassir, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.