Evaluating nuchal translucency scans performed for trisomy screening in a district general hospital between July 1998...

In October 2003, The National Institute for Clinical Excellence recommended screening tests for Down's syndrome (DS) to come into effect from April 2007. These tests were recommended based on studies performed in research centres. Some of the recommended tests have a fetal nuchal translucency scan component. In this retrospective study at the Basildon and Thurrock University Hospital we have evaluated nuchal translucency (NT) scans performed between July 1998 and January 2004 on 18,965 fetuses with a view to comparing our findings with research centres. In spite of our high standards, our detection rate for DS was 72.0% (95% CI 56.0-83.8%) for a 5% false positive rate. This was much lower than the 85% reported from the seminal paper in 1994. We believe that the advice given to women should be based on data from working programmes and not research units.