Non-Invasive Prenatal Testing (NIPT)
Why have NIPT?
Currently screening for Trisomy 21, Down’s syndrome, is offered by the NHS as a combined test between 11+3 to 14+1 weeks. The pregnancy is dated, the fluid at the back of the neck (Nuchal Translucency) is then measured and a blood test from the mother is taken to assess the hormone levels in the blood. This information along with the scan findings is combined and generates a chance of 1:>150 for a low probability result and 1:<150 for an increased probability result. The detection rate is around 70-80% sensitive dependent on the literature you read.
Non-invasive prenatal testing (NIPT) has a 99% probability detection rate – A blood sample from the mother is analysed for fetal DNA which circulates within her blood.
The cell-free DNA can be tested in the most accurate screening process to detect the probability of the baby having Trisomy 21 (Down’s syndrome); trisomy’s 18 (Edward’s syndrome) and 13 (Patau’s syndrome) are also tested. It must be remembered that NIPT is NOT diagnostic giving you a yes or no answer; it is still screening that works in levels of probability and chance.
The effectiveness of this screening test is that it will massively reduce the need to have invasive testing such as an amniocentesis of CVS (Chorionic Villus Sampling) to less than 1% which carries a risk of miscarriage.
A low probability result does not mean there is absolutely no chance and a high probability result will require invasive testing such as an amniocentesis to provide a definitive, diagnostic answer.
The NHS is currently offers this type of testing only for those women with an increased chance/probability from their combined screening.
If you have had a scan after 10 weeks gestation we can offer you a service where we only need to take the bloods. This option can only be performed if you have a scan report showing that you have a viable pregnancy over 10 week’s gestation.
This test does not require any referral from your healthcare providers; it is a safe and non-invasive screening test. All singleton and twin pregnancies whether naturally conceived or by IVF including those with use of donor eggs can be assessed.
The test can be performed from 10 weeks of pregnancy until 40 weeks.
The Scanning Room strongly advise that the mother has all the routine scans offered by the NHS during her pregnancy. The NIPT does not check or provide information on growth problems or physical defects for e.g. Spina bifida, heart or brain abnormalities.
This test does not assess probability for mosaicism, partial trisomy’s or translocations. The findings of the test may not give you a result and may suggest that further testing is more appropriate.
What we do…
A scan needs to be performed to confirm viability and that the pregnancy is over 10 weeks gestation before the paperwork is completed and bloods are taken.
The dating scan is performed over the tummy as transabdominal scan, having a fairly full bladder will help to see the pregnancy more clearly. From 10-14 weeks we measure the baby crown to rump (CRL) to get an estimated due date and over 14 weeks we measure the head, tummy and thigh. Over 14 weeks the due date is based on the head circumference measurement.
The scan can also see if you are having just the one baby or a couple of surprises! We also check your little one to see how well it is developing by checking the skull/brain, arms and legs, stomach and cord insertion.
We also check the uterus and ovaries to ensure everything appears normal.
Throughout the scan we will be talking about what your baby is doing, how it is developing and what it can do – such a lovely insight into your baby’s world.
After the scan we complete the paperwork and you read through and sign the consent form. We then take 1 tube of blood and send this to the lab.
If you are having the bloods only option we will complete the paperwork and take the bloods as above. There is plenty of time to ask any questions.
After the test…
The blood sample is sent to The Doctors Lab in London who have the license to process the samples. The results take up to 10 days to come back to us. Once we receive the results via email, we call you to discuss the findings and then email you the copy of the results. Once you receive the email/results you can always contact us if there is anything you need to discuss.
The results will come back as 0.01% probability which is your low chance result or 99.9% which is your increased probability result. If low probability the report can be put in your notes and no further follow up required. If the results show an increased probability we will with your consent refer you to your screening midwife at your local hospital. The screening midwives will talk you through further options from this point.
In approximately 2% of blood samples taken there is not enough fetal DNA to provide a result. In these cases another sample of blood is requested by the lab which will delay the results being released. If an additional sample is requested this is processed at no extra charge. At times the lab do request further information or clarification about details, in this case we will contact you with the details requested.
For further information follow this link to The Doctor’s Lab website, https://www.tdlpathology.com/specialties/genetics/non-invasive-prenatal-testing-nipt/
13 weeks old.
“I couldn't recommend Lindsay more highly. I had a scan with her at 8+2 and 10+6. She is so warm, kind and caring but also extremely competent, thorough and knowledgeable. She has (at least temporarily!) calmed all my worries and we have some lovely photos of our little one. Thank you Lindsay ”