The 13-week ultrasound scan for pregnant women can provide clarity earlier on, but can sometimes also cause a period of uncertainty. What do (expectant) parents think of the 13-week ultrasound scan? And how reliable are the scan results? PhD candidates Eline Lust (UMC Utrecht) and Kim Bronsgeest (LUMC) investigated these questions together as part of a joint PhD project within the IMITAS study. This study is being used to decide whether the 13-week scan will be permanently introduced in the Netherlands. They are both defending their theses this week.
Since 2021, expectant parents have been able to choose whether to have the 13-week scan. This scan can detect serious physical abnormalities that would otherwise only be visible at the 20-week scan. This gives expectant parents more time to undergo further investigations and to decide how to proceed with the results. The IMITAS study, in which everyone who has a 13-week scan takes part, is investigating whether the benefits outweigh the drawbacks.
The 13-week scan focuses on a limited group of serious conditions. This scan enables doctors to inform expectant parents about any potential conditions and the associated prognosis. However, an ultrasound technician may also detect other abnormalities. As a result, more abnormalities are detected earlier in pregnancy, and expectant parents receive more information about their unborn child. But sometimes more time is needed to reach a diagnosis and establish a clear prognosis.
Eline and Kim investigated how effective the scan is at detecting serious abnormalities and how often it falsely suggests an abnormality. To do this, the researchers analysed data from nearly 130,000 pregnant women who took part in the study between 2021 and 2022. These were pregnant women with a low risk of having a child with a congenital abnormality. All women in the Netherlands are offered this scan as part of the National Screening Programme.
The vast majority of women – around 98 per cent – receive a normal result and can be reassured. This study shows that if the 13-week scan reveals no abnormalities, there is a 1 per cent chance that a mild or severe abnormality will still be detected at the 20-week scan.
Of the participants, 1.3% were eventually told that a possible abnormality had been found. They were referred to hospital for a more detailed scan. Half were subsequently told that everything was fine after all. The other half underwent further investigations, after which a diagnosis was sometimes made and sometimes it turned out that the baby was healthy.
If an abnormality is detected, parents receive information early in the pregnancy – following the 13-week scan – about the severity of the abnormality and what this means for their unborn child. This gives parents extra time to prepare for the baby’s arrival and allows plenty of time to draw up a suitable care plan for after the birth. For parents who decide to terminate the pregnancy in the case of very serious abnormalities, this extra time is also helpful in making appropriate choices. Following a 20-week scan, this time is sometimes only a few days.
As well as looking at the reliability of the scan, Eline and Kim also investigated the psychological impact of the 13-week scan on expectant parents by interviewing them and administering questionnaires. Kim: ‘We looked at the impact of terminating a pregnancy at 15 weeks compared with 22 weeks. This is always an incredibly traumatic event, often accompanied by anxiety, stress and symptoms of depression. It appears that, on average, these symptoms are less severe if the pregnancy is terminated earlier.’ Eline also noted: ‘We need to investigate more thoroughly what support people require, both when they continue with the pregnancy and when they terminate it. There appears to be a need for support and guidance over a longer period.’
Furthermore, the research shows that an abnormal result is associated with greater stress and uncertainty than a normal result. This stress appears to be greater among expectant parents who receive an abnormal result at 13 weeks than at 20 weeks. This may be because not all women had a clear diagnosis when completing the questionnaire following an abnormal 13-week scan, which causes uncertainty.
Eline: ‘Over 85 per cent of the pregnant women who took part in the study believe that the 13-week scan should remain available to pregnant women, and the majority of the healthcare professionals involved agree.’ The results of the IMITAS study are currently with the Health Council of the Netherlands, which is advising the House of Representatives on the future of the 13-week scan. The House of Representatives will ultimately decide whether this scan will be permanently introduced.
Eline: ‘Thanks to close collaboration with many others, we were able to carry out this study. The fact that so many parents and healthcare professionals were willing to share their experiences with us is of great value. We are very keen to hear the Health Council’s advice.’
