First-trimester screening is a test performed between weeks 10 and 13 of pregnancy. It is currently the most reliable screening test for Down syndrome—the most common chromosomal abnormality among babies born today. It also screens for other chromosome abnormalities and birth defects.

The first-trimester screening combines an ultrasound measurement of the skin thickness on the back of the baby’s neck (nuchal transulcency or NT) with a finger-stick blood test performed on the mother. These results are then analyzed and assigned a risk estimate.

For example, the risk of Down syndrome before first-trimester screening could be 1/200 (based solely on the mother’s age). After the test, the lab may reduce the risk for Down syndrome to 1/5000—which is quite reassuring. Although this is a screening test and has limitations, the results of this first-trimester screening can provide significant reassurance your baby is developing normally.

Should I have a first-trimester screening performed?

The American College of Obstetricians and Gynecologists now recommends that all women, regardless of age or family history, be offered first-trimester screening. Ultimately, it is the woman’s choice as to whether she wishes to have this test, but all pregnant women should be offered the test.  Understanding that some women are not able to see their obstetric provider until late in the first trimester, you may call PCI directly to schedule an appointment for this screening.

What are the benefits of having a first-trimester screening completed?

Because first trimester screening can be done earlier than most other prenatal screening tests, you'll have the results early in your pregnancy. This will give you more time to make decisions about further diagnostic tests, medical treatment and the course of the pregnancy. If your baby is diagnosed with a genetic condition, you'll also have more time to prepare for the possibility of caring for a child who has special needs.

Are there any risks associated with this screening?

First trimester screening is a routine prenatal screening test. The test poses no risk of miscarriage or other pregnancy complications.

Do all obstetric offices provide this screening?

Not all obstetric offices are certified to provide this screening. The doctors and staff at PCI are specially trained in providing this first-trimester screening to expecting women. The ultrasound measurement of the skin thickness at the base of the baby’s neck is a very precise measurement and requires additional training and certification to perform properly. Competent laboratories will not perform the test unless the sonographer in the physician’s office is certified to perform the NT. All PCI sonographers are certified in first-trimester screening. PCI doctors continue to attend educational conferences to be on the leading edge in this ever-changing field of prenatal diagnosis and screening to provide patients the highest level of knowledge and care.

Abnormal First-Trimester Screening Results

If you receive abnormal first-trimester screening results— even at another clinic— consider scheduling a follow-up appointment with PCI for further testing. PCI offers both chorionic villus sampling (CVS) and genetic amniocentesis to patients who opt for these tests. Our goal is to schedule follow-up appointments within 48 to 72 hours for patients with abnormal first-trimester screening results to minimize undue anxiety.

Receiving news of a “positive test” can be very alarming, especially when the person relaying the result does not have a thorough understanding of what the results actually mean. PCI offers patients the only certified genetics counselor in central Iowa to assist in this assessment and help you fully understand your results and options for further testing.