How is chromosome testing performed?

Every human individual begins as a single fertilized egg cell, which undergoes continuous cell division to ultimately generate trillions of cells—forming a complete, fully developed person. Thus, the very first cell—the fertilized egg—is critically important. Chromosomal abnormalities in this initial cell can disrupt subsequent cell divisions and ultimately lead to abnormal embryonic or fetal development. So, how are chromosomes examined? The following section addresses this question.

How Are Chromosomes Examined?

For adults, chromosomal analysis is typically performed using a blood sample. For fetuses, different sampling methods are used depending on gestational age: chorionic villus sampling (CVS) during early pregnancy; amniocentesis (amniotic fluid sampling) during mid-pregnancy; and umbilical cord blood sampling during late pregnancy. Chromosome testing helps diagnose congenital disorders caused by inherited or de novo chromosomal abnormalities—including genetic diseases, infertility, and recurrent miscarriage. Additionally, it detects acquired chromosomal abnormalities associated with hematologic malignancies (e.g., leukemia, lymphoma) and solid tumors, thereby aiding diagnosis, guiding clinical treatment decisions, predicting prognosis, and monitoring for disease recurrence.

Knowledge Extension: How to Reduce the Risk of Chromosomal Abnormalities

1. Avoid Harmful Behaviors During Pregnancy

Poor nutrition, smoking, alcohol consumption, and misuse of medications may increase the risk of chromosomal abnormalities in offspring—and also elevate risks of congenital defects, miscarriage, and other adverse pregnancy outcomes. Therefore, women aged 35 years or older who are planning pregnancy or are already pregnant should maintain healthy dietary habits, consume adequate vitamins and protein, abstain from smoking and alcohol, and avoid beverages containing caffeine.

2. Undergo Diabetes Screening

Uncontrolled pregestational diabetes in women does not directly increase the risk of chromosomal abnormalities, but significantly raises the risk of major congenital anomalies—particularly affecting the heart, brain, spinal cord, lower limbs, and kidneys. Women with a family history of diabetes, suspected polycystic ovary syndrome (PCOS), or overweight/obesity are advised to consult their physician prior to conception and undergo diabetes screening.

The above provides an overview of chromosomal testing. We hope this information is helpful to you.