This test looks at the baby’s DNA to detect chromosomal disorders, sex chromosome disorders and the baby’s gender if requested. They are available from 10 weeks. The first part of the test is a Dating Scan to confirm gestation and viability. The second part of the test is a blood test. We take a sample of the mothers blood and send it to the lab to be tested.
The Chromosome disorders detected are commonly known as Down’s syndrome (Trisomy 21), Edward’s syndrome (Trisomy 18) and Patau’s syndrome (Trisomy 13). The Sex Chromosome disorders that can be detected are commonly known as Turner syndrome (XO), Klinefelter syndrome (XXY), Triple-X (XXX) and Jacob’s syndrome (XYY)
The baby’s gender is determined by the presence, or lack of, a Y chromosome in the mothers blood sample.
All of the tests we offer measure the fetal DNA present in a sample of the mothers blood and are available from 10 weeks gestation. All of the tests can be requested for single and twin pregnancies, including IVF pregnancies and pregnancies where a donor egg has been used.
The chart below shows the differences between the 3 tests we offer. If you have any other questions or would like to make an appointment, please contact us and we will be happy to help.
|Available from (gestation)||10 weeks||10 weeks||10 weeks|
|Method / Sequencing||Targeted / Array||Whole Genome||Whole Genome|
|Available for twin pregnancies*||Yes||Yes||Yes|
|Suitable for IVF patients||Yes||Yes||Yes|
|T21 (Downs Syndrome)||Yes||Yes||Yes|
|T18 (Edwards Syndrome)||Yes||Yes||Yes|
|T13 (Patau’s Syndrome)||Yes||Yes||Yes|
|Turner Syndrome (monosomy X)||Yes (optional)||No||Yes (optional)|
|Triple X (XXX)||Yes (optional)||No||Yes (optional)|
|Klinefelter Syndrome (XXY)||Yes (optional)||No||Yes (optional)|
|Jacob’s Syndrome (XYY)||Yes (optional)||No||Yes (optional)|
|Gender identification||Yes (optional)||Yes (optional)||Yes (optional)**|
|T21 detection rate||>99%||>99%||99.14%|
|T18 detection rate||>97.4%||>99%||98.31%|
|T13 detection rate||>93.8%||>99%||98.15%|
|False positive rate||<0.1%||<1%||0.20%|
|Fetal fraction detection rate||4%||< 2%||< 1.4%|
|Redraw / Failure Rate||4.60%||0.20%||0.10%|
|Approximate turn around time***||3-5 working days||3-5 working days||5-7 working days|
* Not suitable for vanishing twins
** Where gender identification is required sex aneploiody will also be reported
*** Time calculated from when sample is received in the labroratory. As labroratories do not express results over the weekend you may wish to consider coming in earlier in the week to avoid delays.