NIPT Procedure at DIAG Medical Center

7-Step NIPT Procedure

Step 1: Consultation with doctors & Completion of Consent Form

Pregnant women receive detailed counseling about NIPT from specialists at DIAG. Afterward, they are required to fill out a consent form before proceeding with the NIPT test.

Step 2: Blood sample collection & Transport to the laboratory

A nurse collects 10ml of maternal blood from a vein. The collection site is sterilized to prevent contamination and ensure sample integrity. The blood sample is then transported to the DIAG laboratory before proceeding with the analysis.

Step 3: Sample reception & Processing

The DIAG laboratory receives the blood sample and processes it, including plasma separation, DNA extraction, and library preparation.

The blood sample is placed in a centrifuge machine to separate the plasma from the red blood cells, white blood cells, and remaining cell fragments, ensuring the purity of the plasma. The resulting plasma contains only the DNA from both the mother and the fetus.

Cell-free fetal DNA (cff-DNA) in the plasma is extracted and retains only the valuable cff-DNA. The extracted cff-DNA is then amplified using the fetal fraction enrichment method (FF%) to ensure an adequate amount for analysis – a process known as library preparation.

Step 4: Whole Genome Sequencing with DNBSEQ™ Technology

The cff-DNA is processed using low-depth Whole Genome Sequencing with DNBSEQ™ technology, developed by BGI Genomics, to perform precise genomic sequencing.

Step 5: Bioinformatics analysis using HALOS software

The sequenced DNA data is analyzed through the Halos bioinformatics platform. This advanced algorithm compares the obtained data with a reference genome and evaluates the risk of chromosomal abnormalities in the fetus.

Step 6: Results Delivery via Zalo/SMS/Website

Pregnant women receive the test results within approximately 7 working days through DIAG’s official online channels, including Zalo, SMS or website.

Step 7: Genetic Counseling

Pregnant women’s NIPT test results are directly consulted by genetic specialists at DIAG Medical Center for further interpretation and guidance.

Understanding NIPT Results

The NIPT results pose risk of chromosomal abnormalities in the fetus.

• Low Risk: This indicates the likelihood of the fetus having chromosomal abnormalities is very low.
• High Risk: This suggests a potential chromosomal abnormality in the fetus. However, a high-risk result is not a definitive diagnosis. Pregnant women should consult a specialist for further genetic counseling and consider confirmatory diagnosis.
• Inconclusive Result: In some cases, the report may state “unable to determine risk.” This can be due to factors such as insufficient sample quality (e.g., hemolysis or low fetal DNA concentration). If this occurs, DIAG Medical Center offers a complimentary retest without additional testing fees.

False-Negative / False-Positive Results in NIPT

False-negative results occur when the NIPT result indicates no chromosomal abnormality, but in reality, the fetus does have a genetic condition.

Possible causes of False-negative results:

• Insufficient cff-DNA concentration in the maternal blood.
• Maternal chromosomal abnormalities, such as rare microdeletions.
• Fetal mosaicism.

False-positive results occur when the NIPT result poses a high risk of chromosomal abnormalities, but the fetus is actually healthy.

Possible causes of False-positive results:

• Pregnant women with Vanishing twin syndrome.
• Maternal chromosomal abnormalities, prior blood transfusions, organ transplant, etc.
• Placental or maternal mosaicism.

Note

NIPT is a prenatal screening test, not a diagnostic test. While it has high accuracy, false-positive and false-negative cases can still occur in a small percentage of results.