Single centre audit of early impact of inclusion of the three vessel and trachea view in obstetric screening

Abstract

Detection rates of congenital cardiac malformations have traditionally remained low. The NHS Fetal Anomaly Screening Programme (FASP) aims to increase these detection rates for various reasons, including influencing perinatal management and aiding parental decision making. The inclusion of the three vessel view and trachea (3VT) view in 2015 aimed to improve detection rates of arch abnormalities in particular. This study evaluated the early impact of the new initiative at one NHS Trust. Departmental screen-positive rates were compared for a full year before and after implementation. Referrals to, and opinions of, the foetal medicine unit (FMU) were assessed; as were undetected congenital heart defects for the two time periods. Compared with the pre-implementation (pre-3VT) period, the number of completed anomaly scans performed after implementation (post-3VT) increased by 3% and the number of FMU referrals increased by 625%. Departmental screen-positive rates for cardiac abnormalities increased from 40% (pre-3VT) to 91% (post-3VT). Over half (52%) of the FMU referrals were made due to a suspected abnormal 3VT view. Early evaluation of 3VT implementation at this NHS Trust indicates that it has been a success. Departmental screen-positive rates for congenital cardiac malformations have risen. However, this performance has come at a cost: Some abnormalities now being detected, such as loose vascular ring and PLSVC, are frequently asymptomatic and likely to be clinically insignificant. The implementation of 3VT achieves the aims of FASP but may begin to exceed what is expected from a low risk population screening programme.