When do nt scan

Individuals born with Down syndrome have an extra copy of chromosome This condition affects 1 in every babies born in the United States. Patau syndrome and Edwards syndrome are rare and often fatal chromosome abnormalities.

Unfortunately, most babies born with these abnormalities die within the first year of life. This test can also include blood work to measure your levels of plasma protein and human chorionic gonadotropin HCG , a maternal hormone. Abnormal levels of either may indicate a chromosome problem. During the screening, your doctor or a technician will take an abdominal ultrasound.

You could alternatively have a transvaginal test, where an ultrasound probe is inserted through your vagina. An ultrasound uses high frequency sound waves to create an image from inside your body.

They can then enter your age or date of birth in a computer program to calculate the risk of your baby having an abnormality. An NT scan cannot diagnose Down syndrome or any other chromosome abnormality. The test only predicts the risk. Talk to your doctor about available blood tests. As with any prediction, the accuracy rate varies. If you combine an NT scan with blood testing, the screening is about 85 percent accurate for predicting the risk of Down syndrome. No special preparation is required for an NT scan.

In most cases, testing is completed in about 30 minutes. The ultrasound pictures may be easier to read if you have a full bladder, so your doctor may recommend drinking water about one hour before your appointment. A NT computer package was developed by the London Fetal Medicine Foundation in the s and was based on more than Strict auditing of the NT ultrasound work performed by every accredited practice in the world is undertaken several times a year.

This ensures that the NT scan test is being performed correctly. Recently, the Royal Australian College of Obstetricians and Gynaecologists has taken over regular auditing of Australian practices. At the end of the first trimester, there is usually a small amount of fluid beneath the skin of the fetus at the back of the head and neck. This fluid is called the nuchal translucency NT , and can be easily and accurately measured to within a tenth of a millimetre.

When there is extra fluid and the NT measurement is thicker than normal, there is an association with chromosomal anomalies such as Down syndrome and some structural abnormalities in the fetus.

Not all babies with an increased NT measurement have Down syndrome or any structural abnormality. There are no after effects of an abdominal or transvaginal ultrasound. You will be able to resume normal activities immediately. Sometimes it will be necessary for the specialist to attend the examination to carry out more scans or to look at the images on the screen rather than just the still pictures taken during the scan.

There are no known risks of having an abdominal ultrasound to the foetus or mother. Ultrasound uses sound waves to obtain images and there is no radiation involved. There is no risk to the foetus or mother, or of miscarriage, if a transvaginal ultrasound is carried out.

The main benefit of screening is to assess the possibility of Down syndrome or other foetal conditions as early as possible in the pregnancy. You will then have the opportunity to discuss the results with your doctor. If screening does identify a possible risk, you might require further definitive tests to confirm the screening results before deciding whether or not to continue with the pregnancy see amniocentesis or chorion villus sampling.

The examination is carried out by sonographers who are specially trained and accredited to carry out the scan. Sonographers may be male or female. If you are not comfortable with a male, you should let the reception staff know this before having the scan. In these cases where the patient is young or has religious or ethnic concerns, a female chaperone can be requested usually a nurse at the radiology facility where you are having the scan, or a female parent or family member.

The sonographer might leave the room to show the images to the radiologist specialist doctor who provides a report to your GP or obstetrician. The radiologist might also carry out further scanning if something needs to be checked.

A full report of the scan will be written and sent to your doctor. In some radiology facilities, only the doctor or specialist will carry out the scan and will usually inform you of the findings. Nuchal Translucency Screening.

Medically Reviewed by Jennifer Wu, M. Medical Review Policy All What to Expect content that addresses health or safety is medically reviewed by a team of vetted health professionals. Learn more about NT screening, an early, noninvasive option that can screen for chromosomal disorders. Back to Top. In This Article. Continue Reading Below. Read This Next. Amniocentesis Test. View Sources. UpToDate, First trimester cystic hygroma and enlarged nuchal translucency , June Prenatal Diagnosis, First-trimester screening for trisomy 21 combining biochemistry and ultrasound at individually optimal gestational ages , July Pregnancy Groups.

Jump to Your Week of Pregnancy. Pregnancy Week. Signs of Labor.