There is a lot to consider and plan for during pregnancy, and our team at ROC is here to help guide our patients through the process with as little worry as possible.
That’s why we offer all types of prenatal screening to patients across all our locations. Prenatal screening is a great place to start to ensure the health and wellbeing of your baby.
Unlike a diagnostic test, a screening test does not give a definite result. However, it can indicate if there is an increased or decreased risk for a particular problem in the developing baby. Screening is advantageous in that that there is no risk to the pregnancy. That said, with screening comes the chance of false positives or false negatives.
Early Prenatal Screening
First trimester ultrasound screening is performed between 11 and 13 weeks gestation. Ultrasound technologists must have special certification to perform first trimester screening.
With ultrasound, a special measurement, called nuchal translucency, is taken. This is a measurement at the back of the baby's neck. With ultrasound the sonographer also attempts to see the nasal bone. The ultrasound measurements help to determine the woman’s risk of having a baby with a chromosomal abnormality such as Down Syndrome. A risk for other abnormalities may also be identified.
Second Trimester Screening
Second trimester screening, such as an alpha fetoprotein (AFP) level, is a blood test that is typically performed between 15 and 20 weeks of gestation. AFP screening can detect an increased risk for open spine defects such as spina bifida.
Non-Invasive Prenatal Screening
Non-invasive prenatal screening, also known as NIPT or prenatal cell-free DNA screening is offered through several different laboratories in the United States, and goes by the names MaterniT21Plus, Panorama, Unity and Prequel to name a few. Circulating cell-free fetal DNA in the mother’s blood is analyzed. This screening has the highest detection rate of any screen currently available, and is more comprehensive.
In addition to screening for Down Syndrome (Trisomy 21), Trisomy 13, and Trisomy 18, cell-free DNA screening will also detect an increased risk for X and Y chromosomal abnormalities. The screen is a blood test, and can be performed from 9-10 weeks gestation on, with results generally available within seven to ten days. Cell-free DNA screening is available for all pregnant women but particularly those in the following categories:
- Advanced maternal age (age 35 or older at delivery)
- Abnormal first or second trimester screen results
- Family history of certain chromosomal abnormalities
- Abnormal ultrasound suggestive of a chromosomal abnormality
While cell-free DNA screening has a high detection rate for the major chromosomal abnormalities, it is not diagnostic, which means false positives do sometimes occur. CVS or amniocentesis would be necessary to definitively rule out or confirm these and other chromosomal abnormalities.
*Screening can provide a woman with reassurance that her pregnancy is not at increased risk for certain abnormalities. If the pregnancy is at increased risk, the patient has the option of a diagnostic test to find out definitively if the baby does have the condition. Knowing the baby has a chromosomal abnormality allows better management of the pregnancy between the patient and her doctor, facilitating a healthier outcome.