Why have the Harmony Test?
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.
The Harmony Test is an option for non-invasive prenatal testing (NIPT) with a 99% accurate chance 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 the Harmony test 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 researching this type of testing and it is believed to be available within the next few years only for those women with an increased chance from the combined screening.
If you have had your combined screening and an increased probability has been generated 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 Harmony non-invasive prenatal test 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.
The Harmony NIPT (non-invasive prenatal testing) is now able to offer a further screening element to the test which is 22q11.2 deletion. This is the underlying cause of conditions described as DiGeorge syndrome and velocardiofacial syndrome (VCFS).
Why is 22q11.2 being included in the Harmony test (and not other microdeletion syndromes)?
The 22q11.2 deletion has been carefully chosen as the only clinically relevant microdeletion syndrome to include with NIPT. 22q11.2 deletion is the most common chromosomal microdeletion, occurring in up to 1 in 1000 pregnancies. Other microdeletion syndromes have a much lower incidence and would increase the false positive rate of the test.
What is the performance of the 22q.11.2 addition?
Inclusion of 22q11.2 deletion is aimed at a screening population, the test has been shown to identify 75% of pregnancies with a 22q11.2 deletion. Therefore, pregnancies with a known higher chance of 22q11.2 deletion, whether found through ultrasound scan or family history should consider invasive diagnostic testing as this test will not identify 1 in 4 (25%) of cases.
There is a false-positive rate of up to 0.5% associated with the 22q11.2 part of the Harmony test. This means that in 200 women with a pregnancy unaffected by 22q11.2 deletion 199 will receive a low probability result and 1 will receive a high probability result.
What is the benefit of finding out that a pregnancy has a high probability of a 22q11.2 deletion?
Early screening and diagnosis of 22q11.2 deletions affects pregnancy management.
Following confirmatory diagnosis of 22q.11.2 deletion the following may be recommended:
Level II ultrasound with fetal echocardiogram to evaluate for anomalies such as congenital heart defect and cleft palate.
Screening for and coordinated management of associated conditions
Delivery at a tertiary care centre
How do I request the 22q11.2 additional test option?
When we complete the paperwork we have the option of selecting the 22q11.2 deletion tick this box if this is required.
The 22q11.2 deletion cannot be requested in twin pregnancies or in pregnancies where the mother has a 22q11.2 duplication or deletion
*There is an additional charge of £100 for 22q11.2 deletion*
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 2 tubes of blood and send these to the lab.
If you are having the bloods only service we will complete the paperwork and take the bloods as above. There is plenty of time to ask any questions.
After the test…
The bloods are sent to The Doctors Lab in London who have the license to process the samples. The results take 7-10 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 discuss whether you would like us to refer you onto the screening midwives at your local hospital or contact them directly yourself. The screening midwives will talk you through further options from this point.
In approximately 3% 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.
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 ”