What is a Nuchal Scan?
Combined screening involves examining the nuchal fold and doing a blood test that will look for the levels of two hormones: pregnancy-associated plasma protein–A and free beta–hCG in the mother’s blood.
The levels may indicate a higher risk of chromosomal abnormalities. This will be combined with the data from the nuchal measurements along with the general risks for the mother based on her age.
Combined screening offers a slightly more informed risk percentage, although it is still not a diagnostic test and cannot be completely accurate.
What happens during a nuchal scan?
During the scan the sonographer will measure the amount of fluid at the base of the neck. On the scan it looks like a black space at the top of the spine. Any measurement of 3mm and above indicates an increased risk.
The foetus will be measured and the precise gestational age calculated. This information, along with details of maternal age will be entered into a statistical analysis programme and your specific odds of having a baby with genetic abnormalities will be calculated. The sonographer will also check to see whether a nasal bone is visible on the scan. Studies have shown that three in four foetuses with Down’s syndrome do not have a visible nasal bone at this stage of development.
You will have a blood sample taken.
It is important to remember that after the nuchal scan you are given a percentage of risk, not a diagnosis. It is an indication of the risk of Down’s syndrome and other genetic abnormalities.
You will receive the results usually between 2 to 4 days by text/telephone and by post within 1 week of the appointment.Meet the team