Nuchal Translucency OB Sonogram with Bloodwork
What is a Nuchal Translucency (NT) OB Sonogram with Bloodwork?
An NT OB Sonogram with bloodwork (NT/freeBeta/PAPP-A) is a first trimester prenatal screening and ultrasound exam that combines a blood test with an 11-13 week Nuchal Translucency Ultrasound exam. Together, this evaluation will report if you have an increased chance of having a baby with Down syndrome, Trisomy 18 or Trisomy 13. These are the most common chromosomal abnormalities, disorders caused by a change in number or structure of the information within our cells. The risk of having a baby with a chromosomal abnormality increases with the mother’s age, but can occur at any age.
How are these studies performed?
Blood is taken to measure the levels of two pregnancy proteins in the mother’s blood: freeBeta HCG and PAPP-A. The OB Ultrasound exam measures the fluid-filled space at the back of the baby’s neck (Nuchal Translucency or NT). This test is safe for you and your baby.
The first trimester NT OB Sonogram with bloodwork screening is one of the most accurate, earliest and safest prenatal screening available. The blood test alone (at 9-14 weeks) identifies 68% of Down syndrome and 90% of Trisomy 18 fetuses (unborn babies). The blood test with the NT measurement (taken between 11 weeks 2 days and 14 weeks 2 days) identifies 91% of Down syndrome, 97% of Trisomy 18 and Trisomy 13, 40% of heart defects, and may indicate some other birth defects. The blood test with the NT measurement and the Nasal Bone Assessment identifies 95% of Down syndrome and 97% of Trisomy 18 and Trisomy 13.
What are Down syndrome, Trisomy 18 and Trisomy 13?
Down syndrome occurs when there is an extra copy of chromosome 21. Individuals with Down syndrome have mental retardation and often physical anomalies, like heart defects. Trisomy 18 occurs when there is an extra chromosome 18; Trisomy 13 when there is an extra chromosome 13. Both disorders can cause mental retardation and other birth defects. While Trisomy 18 and Trisomy 13 are more severe than Down syndrome, they are less common. These three disorders make up approximately half of the chromosomal abnormalities seen at live birth. The NT OB Sonogram with Bloodwork may detect some, but not all, of the remaining chromosomal abnormalities.
Who should be offered this examination?
The NT OB Sonogram with Bloodwork should be offered to all women less than 34 years of age with no family history of chromosomal abnormalities or women less than 33 years who are carrying twins. Women who will be 35 years of age or older at the time of delivery, who will be 33 years and carrying twins, or who have a family history of chromosomal abnormalities, are routinely offered Chorionic Villus Sampling (CVS) or amniocentesis for prenatal chromosomal diagnosis. CVS and amniocentesis are methods of collecting a sample for chromosomal analysis with a detection rate of 99.9% of all chromosomal abnormalities.
NT OB Sonogram with Bloodwork is not a substitute for a diagnostic test. Women who decline diagnostic testing like CVS or amniocentesis may pursue an NT OB Sonogram with blood work, accepting these limitations:
- Does not diagnose or rule out specific conditions.
- Estimates risks for only 3 chromosomal abnormalities.
- Will miss some chromosomal abnormalities diagnosed by CVS or amniocentesis.
- May falsely reassure some patients who, even after screening, have an increased risk for chromosomal abnormality due to age or family history.
What if my screening test shows my risk is increased?
An increased statistical risk on a screening test does not mean a chromosomal abnormality has been diagnosed. You will be offered genetic counseling and a diagnostic CVS or amniocentesis for chromosomal analysis.
What if my NT OB Sonogram with Bloodwork result is in a normal range?
A result in the normal range on a screening test reduces your statistical risk, but does not rule out Down syndrome, Trisomy 18 or Trisomy 13.
What about a repeat screen?
Repeat chromosomal screening is not a standard of care nor is it recommended. A follow-up triple or quad screen is unlikely to improve detection.
How do I schedule my NT OB Sonogram with bloodwork?
NT OB Sonogram appointments can be scheduled by calling WRA at 703-280-9800. WRA performs NT OB Sonogram studies at our offices in DC, Fairfax, Sterling and Bethesda
Will other blood tests be required?
Your referring physician, in consultation with you, will choose the appropriate blood test to order. Please note, in cases where the referring physician has ordered a Sequential or Integrated screening, you will need to have additional bloodwork performed at a later date. This will be coordinated with the patient by the referring physician/OBG office.
WRA Nuchal Translucency OB Sono Locations
Washington, DC
University Medical Building
2141 K Street, NW, Suites 200 & 900
Washington, DC 20037
202-223-9722
Suburban Maryland
Camalier Building
10215 Fernwood Road, Suite 50
Bethesda, Maryland 20817
301-564-1053
Northern Virginia
Four Seasons Three
3022 Williams Drive, Suites 200 & 204
Fairfax, Virginia 22031
703-698-8800
Lakeside @ Loudoun Tech Center I
21351 Ridgetop Circle, Suite 150
Sterling, Virginia 20166
571-434-0140
Scheduling Appointments
Washington Radiology provides imaging services for patients upon referral from a physician. Patients are seen by appointment. However, emergencies do occur and we make every attempt to accommodate these cases. To schedule an appointment at Washington Radiology, please call: (703) 280-9800.
