RT Journal Article SR Electronic T1 G162 Impact of national prenatal screening guidelines on the detection rates of transposition of the great arteries in neonates undergoing the arterial switch procedure JF Archives of Disease in Childhood JO Arch Dis Child FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP A69 OP A70 DO 10.1136/archdischild-2015-308599.158 VO 100 IS Suppl 3 A1 DC Gardner A1 JL Heaps A1 CB Jones A1 JSL Lim YR 2015 UL http://adc.bmj.com/content/100/Suppl_3/A69.2.abstract AB Aims Prenatal diagnosis of transposition of the great arteries (TGA) has been shown to improve pre-operative clinical condition and long term outcome. In 2008 the National Institute of Clinical Excellence (NICE) published guidelines advising that ventricular outflow tracts should be assessed as part of the routine prenatal assessment and this was consolidated in the 2010 FASP guidelines. This had a large impact on sonographer training requirements and although skills are increasing, prenatal detection differs significantly by region. Our aim was to review the effect of these new guidelines on our prenatal detection rate and evaluate the impact of these changes on our patient population. Method All patients undergoing the arterial switch procedure (ASO) for simple TGA between 2001 and 2013 were identified. This enabled assessment of patient outcomes before and after the introduction of the 2008 NICE guidance. Patients with septal defects were included but those with additional CHD were excluded. A retrospective review of patient records was performed. Data was gathered regarding patient demographics, timing of diagnosis and subsequent admission to the cardiac centre. For patients admitted, their pre-operative status, surgical intervention and immediate and long term outcomes were reviewed. Results 219 patients with simple TGA +/- septal defects who had the arterial switch procedure were identified during the 13 year period. The rate of antenatal diagnosis has been consistently increasing since 2008 (see Figure 1), from 11% prior to 2008 to 41% from 2008 onwards and 62% in the most recent year. Abstract G162 Figure 1 Trends in timing of diagnosis for neonates with TGA +/− VSD undergoing the arterial switch procedure at our institution Conclusions Nationally antenatal diagnosis of congenital heart disease is improving according to CCAD data. Locally our prenatal diagnosis rate has been consistently increasing since 2007 but there remains room for improvement with higher prenatal detection rates in other regions. Further analysis is required to determine the outcome following a prenatal diagnosis both regionally and nationally.