Objective To assess the rate of chromosomal problems with complete atrio-ventricular septal defect. This study was undertaken to improve counselling and provide better information for expecting parents in the future.

Methods All cases of complete atrio-ventricular septal defect detected antenatally between January 2002 and December 2008 were included in the study. Fetal medicine and fetal cardiac databases at a tertiary fetal cardiology centre as well as CARIS central database in Wales were utilised to carry out the review. The notes were carefully scrutinised to rule out any confounding variables.

Results There were 47 cases of CAVSD in South Wales over this period, 32 of which were detected antenatally. Ten of these were terminated following counselling and three ended up in still birth with one fetal loss. Hence, there were 18 live births with HLHS. Of these, six died postnatally, five of these had chromosomal problems.

23 of the cases diagnosed antenatally had chromosomal problems. 8 of the 10 terminations were complicated with associated chromosomal problems. Two out of the three stillbirths and the fetal loss was also complicated by associated chromosomal anomaly. Out of the 18 live births, 12 had chromosomal problems.

Trisomy 21 was the commonest karyotypic abnormality (18 out of 23) in CAVSD with Trisomy 18 comprising the remainder.

Conclusion CAVSD is a common congenital heart defect. Antenatal detection rate for CAVSD stands at 68% in Wales. It is associated with a high rate of chromosomal problems (72%). Counselling is essential for parents to make an informed decision.