Non Invasive Prenatal Testing (NIPT)
In the event of a high-risk screening result following 1st or 2nd trimester assessment, NIPT is a recently available option for higher accuracy screening for the most common chromosomal abnormalities without posing any risk of miscarriage to the pregnancy.
It requires a blood sample from the mother, from which fetal DNA is extracted. The chromosomes analysed are chromosomes 21 (for Down’s Syndrome), 18 (Edward’s Syndrome) , 13 (Patau’s Syndrome) as well as the X and Y chromosomes. The accuracy of detection for Down’s, Edward’s and Patau’s Syndromes are 99%, 97% and 92% respectively.
Currently, the blood has to be couriered to a laboratory in the United States, The Panorama Laboratory, as there are no South African laboratories that perform this analysis. Results may therefore take up to two weeks, and we would notify the patient telephonically on receipt.
The success of the test is dependant on the fraction of fetal DNA extracted from the maternal blood sample, and occasionally the results may be inconclusive. There is also a small false-positive rate of 0.1%. Therefore, in the event of a positive or inconclusive result, an invasive diagnostic test (amniocentesis) would be offered.