The MaterniT21 test is a non-invasive prenatal screening (NIPS) that offers expectant parents information about the likelihood of certain genetic conditions in their developing baby. This test analyzes fragments of cell-free DNA (cfDNA) circulating in the mother’s bloodstream, a portion of which originates from the placenta. Because it requires only a simple blood draw from the mother, it carries no risk of miscarriage, unlike traditional diagnostic procedures. Understanding the process and the conditions being screened for can help manage the anxiety often associated with waiting for these results.
What Does the MaterniT21 Test Screen For?
The MaterniT21 test screens for the most common chromosomal abnormalities, which are conditions caused by an extra or missing copy of a chromosome. The core analysis focuses on the three most prevalent trisomies: Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). These conditions are associated with the presence of three copies of a specific chromosome instead of the usual two.
The test is typically performed starting at nine or ten weeks of gestation because a sufficient amount of fetal cell-free DNA must be present in the maternal blood sample for an accurate reading. The analysis can also determine the sex of the fetus by examining the sex chromosomes. Screening can be extended to include sex chromosome aneuploidies, such as Turner syndrome (a single X chromosome) or Klinefelter syndrome (XXY).
An expanded MaterniT21 panel can also screen for select microdeletion syndromes, which are conditions caused by the absence of a small piece of a chromosome, such as DiGeorge syndrome (22q deletion). The test uses next-generation sequencing technology to measure the count of specific chromosomal material present in the maternal blood sample. It is important to remember that this test is a screen, meaning it assesses risk rather than providing a definitive diagnosis.
Standard Turnaround Time and Potential Delays
The time it takes to receive MaterniT21 results generally falls within a window of five to ten calendar days from the day the blood sample is collected. The laboratory analysis itself is the most rapid portion, often taking between three and five calendar days once the sample arrives at the lab. The overall timeline, however, begins with the blood draw at the healthcare provider’s office and involves several steps before analysis can even begin.
The sample must be properly packaged and shipped from the collection site to the specialized laboratory for processing. This logistical step can add several days, particularly if the collection occurs right before a weekend or a national holiday. Once received, the lab processes the blood to isolate the cell-free DNA, then performs the sequencing and complex bioinformatics analysis before a final report is generated.
The most common cause for a delay is an initial “No Result” due to insufficient fetal fraction. This is the percentage of the total cfDNA in the mother’s blood that belongs to the fetus. The lab requires a minimum fetal fraction for accuracy, and this fraction can be low early in pregnancy or in individuals with a higher body mass index. If the fetal fraction is too low, the patient will need a redraw, which adds another week or more to the waiting period.
Administrative issues can also contribute to delays in the transmission of results. Insurance pre-authorization is sometimes required before the lab will process the sample, and any holdup in this approval process can postpone the start of the analysis. It is advisable to confirm the expected timeline directly with the ordering healthcare provider or the laboratory, as processing volumes and logistics can cause the actual wait time to fluctuate.
What Happens After Results Are Received?
Once the laboratory completes its analysis, the official report is sent to the ordering healthcare provider. The results are typically organized into one of three categories: Negative, Positive, or Inconclusive/No Result. A Negative result indicates a significantly decreased likelihood that the fetus has the screened-for condition, providing considerable reassurance.
A Positive result, also referred to as “High Risk,” suggests an increased chance that the fetus may be affected by the condition. It is important to remember that the MaterniT21 test is a screen, not a definitive diagnosis. A genetic counselor or physician will review the result, explaining the concept of Positive Predictive Value (PPV)—the actual probability that a positive result is a true positive—which can vary based on the mother’s age and background risk.
For any High Risk result, the next recommended step is a consultation with a genetic counselor, followed by an invasive diagnostic procedure for confirmation. Procedures such as chorionic villus sampling (CVS) or amniocentesis analyze cells from the placenta or amniotic fluid and provide a definitive diagnosis. The Inconclusive or No Result outcome, often caused by low fetal fraction, necessitates a discussion about whether to attempt a redraw or proceed directly to other screening or diagnostic options.