Antenatal scans save heart disease babies’ lives

Babies with life-threatening but treatable heart disease are more likely to survive if the disease is picked up before birth a new study shows – but researchers say too few pregnant women in Aotearoa New Zealand receive an antenatal diagnosis.

In New Zealand, four babies die each year due to late-diagnosed congenital heart disease. The condition – where the heart doesn’t form properly - is the leading cause of infant deaths related to birth defects. If the condition is picked up prior to birth, care after birth means babies remain well until treated with surgery – usually within the first week. Survival rates are excellent; in the nine years covered by this study, all babies who received the treatment survived.

But the study also showed, for the first time, how much of a difference early detection makes.

Researchers from the University of Auckland-based Liggins Institute and Starship Child Health analysed all recorded cases of two variants of the condition in babies born at term between 2006 and 2014 – a total of 253 babies. One percent (one) of babies diagnosed before birth died, compared to seven percent (11) of babies diagnosed following birth. Overall, fewer than half of babies were diagnosed before birth, though the figure rose from 32 percent in the first three years to 47 percent in the last three years.

Lead author Dr Elza Cloete from the Liggins Institute says the difference in survival rates was largely because early diagnosis can allow for arrangements for the mother to give birth at Auckland City Hospital, which is next door to the country’s only child heart surgery centre at Starship Children’s Hospital.

But if the diagnosis is made following birth, mother and baby have to be transferred urgently to Starship Hospital. This delay can cost the baby’s life.

Reasons for a missed antenatal diagnosis include the mother being unable to access an appropriate antenatal ultrasound scan at the right time, or the defect not being detected during the scan. This can be due to a variety of reasons including the length of time set aside for the scan, the technical difficulty of the scan, the skill of the sonographer, and high BMI in the pregnant woman making it more challenging to gain clear images.

“Our findings highlight the need to ensure all pregnant women can access high quality antenatal scans at the right times, regardless of where they live,” says Dr Cloete, a Liggins Institute PhD student and neonatologist.

“Encouragingly, there has been an improvement in antenatal detection, probably due to sonographer training, greater awareness of this condition and recent guidelines about which pictures should be obtained during the scan. But we must continue striving to improve antenatal detection rates through better access to scans of sufficient quality to detect these problems.”

Radiologist Dr Rachael McEwing was a member of the Ministry of Health’s Maternity Ultrasound Advisory Group, which made recommendations to the Ministry for improved
quality control and audit of maternity scans.

“This study highlights the importance of high quality scanning and audit,” she says.

She adds that one of the heart conditions covered in the study is generally only able to be diagnosed in the third trimester, and third trimester scans are not routine at present.

The other two researchers were Professor Frank Bloomfield, Liggins Institute Director and neonatologist at National Women’s Health at Auckland City Hospital, and Dr Tom Gentles, Director of the national paediatric cardiac service at Starship Child Health.

© Scoop Media