You can urinate as soon as the test is done. For a transvaginal ultrasound, a small transducer will be inserted into your vagina. The test usually takes about 15 to 20 minutes. During a nuchal translucency test, you may have a feeling of pressure in your bladder.
For an abdominal ultrasound, the gel may feel cool when it is first put on your belly. You'll feel a light pressure from the transducer as it passes over your belly.
For a transvaginal ultrasound, you may feel some pressure when the transducer is in your vagina. There are no known risks linked with a nuchal translucency test, either to you or the baby. But you may feel anxious if the test shows that there's an increased chance that your baby may have a problem. Ultrasound is a safe way to check for problems and get information about your developing baby. It doesn't use X-rays or other types of radiation that may harm the baby.
Your doctor will look at the results of the nuchal translucency test to see if the area at the back of the baby's neck is thicker than normal. You may not receive information about the test right away. Full results are usually ready in 1 or 2 days.
The test can find out if your developing baby fetus is at higher-than-normal risk for problems. But it can't tell for sure that the baby has a problem. You would need another test, called a diagnostic test, to make sure. The accuracy of this test is based on how often the test correctly finds a problem. For example:. To help a parent be informed and reduce the chance of having a baby with a disability, Ultrasound Care offers our future parents an optional Nuchal Translucency Screening test during pregnancy which lets you know if your baby is possibly affected with Down syndrome.
Down syndrome is a condition that results in intellectual disability of varying degrees and may cause physical problems such as heart defects, or difficulties with the sight and hearing. About 1 in babies born in New South Wales will have Down syndrome. Although all women have a risk of having a baby with Down syndrome, this risk increases with the age of the woman. Down syndrome is a chromosome abnormality. It is caused by having 3 rather than 2 copies of chromosome number There is no risk to the baby from either of these procedures.
By itself the test does not tell you whether or not the baby has Down syndrome, but gives you an individualised risk which may help identify whether you would like to test the pregnancy further. The nuchal translucency test can be done between 11 and a half weeks and 14 weeks of pregnancy ideally late in the 12th week.
To allow us to ensure you receive the results on the day of your ultrasound, the blood test must be taken at least a few days before the ultrasound is performed, preferably at 10 weeks. If the blood test result is available, the combined results of the two tests will usually be available soon after the ultrasound examination. This does not necessarily mean that there is a problem in your pregnancy, but it does mean you should consider further tests to see if there is a problem.
Other tests we may recommend involve further screening with cell free fetal DNA testing or diagnostic testing with chorionic villus sampling or an amniocentesis. This means that the risk of having a baby with Down syndrome is very low but unfortunately, it does not mean that there is no risk.
No, the decision is your choice entirely, but the combination of the two tests allows a more accurate result. The decision whether to be tested is entirely up to you. You'll get your results in the form of a ratio that expresses your baby's chances of having a chromosomal defect. For example, a risk of 1 in means that for every women with this result, one baby will have Down syndrome and 99 will not.
A risk of 1 in 1, means that for every 1, women with this result, one baby will have it and 1, will not. The higher the second number, the lower the risk.
You may also be told that your results are "normal" or "abnormal" for a particular condition, depending on whether the ratio is below or above a specified cutoff. For example, some tests use a cutoff of 1 in So a result of 1 in 1, would be considered normal because the risk that there's a problem is lower than 1 in A ratio of 1 in would be considered abnormal because that risk is higher than 1 in Remember that a normal screening result screen negative isn't a guarantee that your baby has normal chromosomes, but it does suggest that a problem is unlikely.
Likewise, an abnormal screening result screen positive doesn't mean that your baby has a chromosomal problem — just that your baby is more likely to have one. Most screen-positive babies turn out not to have a problem: Only about a third of babies with an increased nuchal translucency measurement turn out to have chromosomal defects. The NT scan alone will detect about 70 to 80 percent of babies with DS depending on which study you look at.
The detection rate for the NT scan plus a first-trimester blood test ranges from 79 to 90 percent. Most tests will include both the NT scan and the blood test. This does not mean that a screen-positive baby has a 79 to 90 percent chance of having DS.
It just means that 79 to 90 percent of babies who have DS will have screening results that are suspicious enough to recommend diagnostic testing. And 5 to 21 percent of babies who have DS will be determined to be at normal risk — that is, the results will be misleading. Screening tests aren't perfect. They don't detect all cases of DS, so they may identify your baby as being at low risk when they really do have DS.
In other words, if you're carrying a baby with DS, there's a 79 to 90 percent chance that the combined screening will detect the abnormality and give you what's called a screen-positive result indicating that further testing is recommended.
But it also means there's a 5 to 21 percent chance that the tests will miss the DS and give you a screen-negative result. This is called a false negative result, and it might lead you to decide against diagnostic testing that would have revealed a problem. These tests also have a 5 percent false-positive rate. Keep in mind that nuchal translucency is not percent accurate.
In general, most doctors consider a normal screening NT measurement at 12 weeks to be under 3 mm. A nuchal translucency screen is recommended for all pregnant women and is often one of several routine prenatal tests during the first trimester. The results can help you make prenatal care decisions. Although NT is widely available, some rural and urban areas may not have the resources to perform the procedure. After that, the tissue gets thicker and is no longer translucent, so test results become inconclusive.
An NT is a special type of ultrasound using a very sensitive but safe machine. A sonographer will apply a transducer wand to the outside of your stomach to measure your baby from crown to rump and check that the fetal age is accurate. Then he or she will locate the nuchal fold and measure its thickness on the screen. Those measurements, plus your age and baby's gestational age, will be entered into an equation that calculates the probability of a chromosomal abnormality.
Although this number can't give you a definitive diagnosis, it can help you decide whether you want to undergo diagnostic testing. Nuchal translucency screening has a relatively high rate of error when performed by itself. To improve the accuracy of results, your practitioner will likely offer what's known as a combined screening.
NT results by themselves have an accuracy rate of about 70 percent. That means that the test misses 30 percent of babies with Down syndrome or other chromosome disorders. Including the NT as part of a first trimester combined screening improves detection to between 83 and 92 percent.
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