Fetal cardiac screening and variation in prenatal detection rates of congenital heart disease: why bother with screening at all?

Abstract

Antenatal screening for fetal cardiac abnormalities was introduced over 25 years ago, yet detection of congenital heart disease before birth remains a challenge. While experienced tertiary centers report a high level of diagnostic accuracy, with most major forms of congenital heart disease being detectable before birth, the overall detection rate remains low. Pregnancies at increased risk of having an affected baby are referred to tertiary centers for fetal ECG, but most cases of congenital heart disease will occur in low-risk pregnancies. These cases will only be detected by screening the low-risk population at the time of routine obstetric scanning. Many obstetric ultrasound units have learnt to successfully obtain, and correctly interpret, views of the heart, including the four-chamber view and outflow tract views. However, standards for doing this are not uniform, nationally or internationally, so there is a significant variation in detection rates across individual countries and between different countries. Early diagnosis of babies with lesions that can result in cardiovascular collapse and death, could improve their survival as well as reducing morbidity. In addition, detection of a cardiac abnormality during pregnancy allows time to prepare parents for the likely course of events after birth. It also facilitates detection of other abnormalities in the baby and gives parents a choice, even if the choice is difficult and unwelcome. As well as providing parents with accurate and up-to-date information regarding the their baby’s abnormality, it is vital to provide continuing support to help them deal with the problem, regardless of what decisions they make. Much work remains to establish a uniform standard for antenatal detection of cardiac abnormalities. More recent national guidelines for examining the fetal heart along with formalized auditing processes should help to achieve this, although considerable time and effort will be required, particularly with regard to the teaching and training required.