From the Guidelines
A Trio test, also known as the Triple Screen test, is a prenatal test that measures the levels of three substances in a pregnant woman's blood to screen for fetal open neural tube defects and aneuploidy, specifically trisomies 21 and 18, and can be undergone at a healthcare provider's office or a specialized prenatal testing center. This test is typically performed between 15 and 20.9 weeks of gestation, with the optimal time being at 16 to 18 weeks gestation 1. The test measures the levels of maternal serum alpha-fetoprotein (MSAFP), human chorionic gonadotrophin (hCG), and unconjugated estriol (uE3) to adjust a woman's age-risk for Down syndrome and other fetal abnormalities.
What the Test Measures
- MSAFP levels to detect open neural tube defects and anencephaly
- hCG levels to detect trisomies 21 and 18
- uE3 levels to detect trisomies 21 and 18
Where to Undergo the Test
A patient can undergo a Trio test at:
- A healthcare provider's office
- A specialized prenatal testing center
- A hospital with prenatal testing capabilities It is essential to inform the laboratory of the gestational age at the time the sample was drawn for an accurate interpretation, as well as other factors such as maternal weight, race, presence of insulin-dependent diabetes, number of fetuses, and family history of open neural tube defects 1.
Importance of Accurate Testing
The test is most accurate if the laboratory is informed of the necessary factors, and ultrasound dating of the pregnancy reduces the false-positive rate and increases the detection rate of open neural tube defects 1. If there is a discrepancy in gestational age of 2 or more weeks after an ultrasound examination, then the test result must be reinterpreted. Genetic counseling and additional testing such as targeted ultrasound examination and amniocentesis are recommended for pregnancies with an elevated MSAFP test result 1.
From the Research
Definition of Trio Test (Triple Screen Test)
- The Trio test, also known as the Triple Screen test, is a prenatal genetic screening test designed to assess whether a patient is at increased risk of having a fetus affected by a genetic disorder 2.
- This test is intended to provide an assessment of the woman's risk of carrying a fetus with one of the more common fetal aneuploidies, such as Down syndrome (trisomy 21) 3, 4.
Where to Undergo a Trio Test
- The Trio test can be performed at various medical facilities, including obstetrician-gynecologist (OB-GYN) offices, prenatal care clinics, and hospitals that offer prenatal screening services 3, 2.
- It is essential for patients to discuss their options with their healthcare provider to determine the best course of action for their individual needs and risks 4, 5.
Types of Prenatal Screening Tests
- There are various prenatal screening tests available, including first-trimester risk assessment, maternal serum analyte (quad) screening, and sonographic fetal structural survey 5.
- Non-invasive prenatal testing (NIPT) is a relatively new and highly accurate technique that uses maternal serum to detect chromosomal disorders, such as trisomy 21 (Down syndrome) 4, 5.
- The choice of screening test depends on several factors, including the patient's age, medical history, and personal preferences 3, 2.