Nuchal scanning at MUMS
Since November 2003 we have performed 18426 nuchal scans at MUMS. We have detected 125 cases of Downs syndrome and missed 10 cases.
This therefore gives us a detection rate of 92% for all cases of Downs syndrome
Of the 10 cases of Downs missed, three were detected by the 20 week ultrasound scan.
Overall 6% of women received a high risk result over this period.
In view of the fact that most women who received a high risk result did not have a pregnancy with Downs syndrome we have decided to reduce our cut off risk for high risk to 1 in 150 instead of 1 in 250.
This will enable us to reduce the number of women having a high risk result but having a normal pregnancy BUT at the same time not reducing our detection rate for Downs syndrome.
We should now see our high risk result chances reduce to between 1 and 2%.
This is in line with the current national recommendations for screening in the first trimester.