The detection of first trimester ultrasound in the diagnosis of congenital heart defects: A narrative review

The authors of the article “The detection of first trimester ultrasound in the diagnosis of congenital heart defects: A narrative review” published in Sonography, would like to thank the author/s of the letter to the editor for their kind comments and for taking the time to respond to our work. We agree the studies reviewed were heterogenous in nature and for this reason the results were not pooled but were presented as mean values and ranges as has been recommended. We presented a list of congenital heart defects (CHD) that were detected or missed in the first trimester stating fetal heart size as one reason CHD is missed. We acknowledge evolution of CHD as suggested would have strengthened our argument. We also agree that lack of follow-up after CHD diagnosis is problematic when reporting the results of studies. While the skill level of a sonographer performing a first trimester ultrasound and the use of first trimester combined screening by a nuchal translucency ultrasound education and monitoring program (NTUEMP) certified sonographer, utilising tools such as nuchal translucency, ductus venosus and nasal bone assessment may improve the detection of CHD, we are unaware of any evidence that suggests a relationship between NTUEMP certification and the ability to scan the fetal heart. Furthermore, NTUEMP does not include formal assessment of the fetal heart in the course content nor in reaccredidation. Of the 6908 Australian accredited sonographers only 23% are currently nuchal translucency accredited. Indeed, operator training for heart screening views appears to be a major determinant for successful screening for CHD. Recent work suggests intention to perform screening is also important. This highlights the importance of education for sonographers for first trimester screening of the fetal heart. We agree there is a need to differentiate between screening for CHD and a diagnostic fetal echocardiography scan in the first trimester. We also agree that claiming high-detection rates for CHD screening in the first trimester is problematic. Our review of the current literature concluded the results would not be generalisable to low-risk general radiology or obstetric practices as the majority of first trimester CHD studies were performed by paediatric cardiologists. Further research is needed to determine if education, training, and intention to assess the fetal heart in the first trimester will improve detection rates in low-risk populations when scans are performed by general sonographers.