No! Fetal sex or gender, just like every other part of NIPS, is considered a screening test. While this is by far the most accurate part of NIPS, false results do occur. If you do receive an incorrect fetal sex prediction through NIPS, which is usually noticed at your 20 week ultrasound, do not panic. This does not necessarily mean anything is wrong with the baby. There are many reasons NIPS can predict the incorrect fetal sex or gender.
Both are screening tests that assess the risk for Down syndrome and trisomy 18 in pregnancy by looking at a sample of a mother’s blood.
First trimester screening measures the levels of two proteins in the mother’s blood (PAPP-A and hCG) and combines those results with a 12 week ultrasound to look at a measurement on the back of baby’s neck called the nuchal translucency. Combining these numbers provides a risk for the pregnancy to have Down syndrome or trisomy 18.
NIPS looks at small pieces of chromosome material released by the placenta into the mother’s blood stream. No ultrasound is included for the risk analysis. NIPS additionally screens for trisomy 13 and sex chromosome (X and Y) differences in a pregnancy, as well as fetal sex. NIPS is also more accurate at screening for Down syndrome and trisomy 18 than first trimester screening. However, a nuchal translucency scan (part of the first trimester screen) can detect other concerns such as an increased risk for a baby to have a heart defect.
It is important to remember both tests are just screening tests and neither can diagnose or rule out a condition in pregnancy.
NIPS has detected a small number of cases of maternal cancer during pregnancy. However, these results look very different from a standard positive NIPS result. Often, these results come back positive for many chromosome conditions, giving both the laboratory and the genetic counselor an idea that something beyond the pregnancy may be going on. For example, these results will often say a baby has trisomy 18 AND monosomy 13, while the baby looks perfectly healthy on ultrasound. If you have had a positive NIPS result that turned out to be a false positive, you should not worry about an increased risk for cancer. Fortunately, most laboratories now can tell when an NIPS result is indicating the possibility of maternal cancer, and this would be discussed with you along with your results.
Unfortunately, no. While the risk for Down syndrome, trisomy 18, trisomy 13, Turner syndrome, and Klinefelter syndrome drops to 1 in 10,000 with a “negative” NIPS result, this risk is not 0. While false negatives are rare, they do occur.
Most insurance companies will cover NIPS for a woman of any age as it is the recommended test for all women interested in screening during pregnancy. However, some insurance companies deny all genetic screening and testing as an exclusion in their policy. If your testing is denied by insurance most NIPS companies will allow you to pay a reduced rate that can range from $100-$350 depending on the company. Ask your provider what company they use and what specific billing policy that company has to determine your exact price.
Not necessarily. Most companies use very similar technologies for NIPS. Your genetic counselor or health care provider can help determine if one particular company is preferable based on your specific needs. However, for traditional NIPS most companies are equal in accuracy.
Yes. Women who have undergone an organ transplant are not good candidates for NIPS. This is because small pieces of the organ donor’s DNA will be screened with the pieces of fetal DNA, giving an inaccurate result. Additionally, women who are currently affected with cancer should not undergo NIPS, since cancer cells often have chromosome differences that may lead to a false positive NIPS result. Finally, women on blood thinners such as Lovanox or Heparin are significantly more likely to have a non-reportable result, and should consider other screening options.
Standard NIPS only screens for Down syndrome (trisomy 21), trisomy 13, trisomy 18, Turner syndrome (monosomy X), Klinefelter syndrome (XXY), and other possible sex chromosome differences. Most birth defects are not caused by these conditions. Therefore, a negative NIPS cannot identify your risk for other birth defects or genetic conditions.
Yes. In over 95% of cases of Down syndrome there is no family history of this condition. The same can be said for trisomy 13, trisomy 18, Turner syndrome, and Klinefelter syndrome. Therefore, not having a family history of one of these conditions does not decrease your risk for these conditions below your age related risk in pregnancy.
Similarly, having just one affected relative with one of these conditions does not significantly increase your risk, since that condition was likely new to that person in your family and not inherited. However, having two or more relatives with same chromosome condition may imply an increased risk for that condition.
No. The sensitivity and specificity refer to the ability of the test to accurately call a negative result negative, or a positive result positive. If you’re screening result is “positive” (remember, this is not a diagnosis), the risk is based on your age and the specific condition. This is because the risk for many of the conditions screened for by NIPS increases each year as a woman ages. So as a woman ages, it is more likely for a positive to be a true positive.
For example, a 21-year-old woman who has a “positive” NIPS for trisomy 13 actually has just a 6% risk that the pregnancy is actually affected. This is because trisomy 13 is a rare condition, NIPS is not as accurate for trisomy 13 as other conditions, and because of her age, her starting risk was very low.
A 35-year-old woman who has a “positive” NIPS for Down syndrome however, has a 79% chance that the condition is actually present, because her starting risk based on her age was higher, NIPS is most accurate at screening for Down syndrome, and Down syndrome is more common in the general population.