The role of first-trimester ultrasound has evolved from the measurement of
crown-rump length (CRL), nuchal translucency (NT) and nasal bone to involve more
detailed assessment of fetal anatomy. The majority of cardiac malformations are
properly defined and potentially detectable by the time of the 11-13+6 week ultrasound
examination. The sensitivity of ultrasound screening for cardiac abnormalities varies
according to the marker being assessed (increased NT, tricuspid regurgitation,
abnormal ductus venous flow), operator experience and the extent of a protocol for
formal sequential structural assessment of the heart. All cardiac structures can be
visualised from 13 weeks onwards. Early fetal echocardiography has been shown to be
feasible and highly sensitive and specific in experienced hands. Early identification of
cardiac abnormalities allows the assessment of chromosomal abnormalities/genetic
syndrome at an early stage, giving parents more reproductive autonomy. Operators
should be aware of the limitations of an early cardiac examination: Some lesions
progress as pregnancy advances and there is still a need for a follow up ultrasound at
20 weeks’ gestation.
Keywords: Cardiac abnormalities, Early fetal echo, Prenatal screening.
