Integrated fetal testing in growth restriction: combining multivessel Doppler and biophysical parameters

The assessment of fetal growth, development and health are considered standard care in most societies. Surveillance has been applied to pregnancies complicated by intrauterine growth restriction (IUGR) to improve fetal outcome. But antenatal fetal surveillance is evolving. It is no longer adequate to act only at the last moment to prevent fetal mortality. Rather, we aim to identify critical risk factors and improve outcome by directing appropriately timed intervention. And it is the timing of intervention that is perhaps the greatest challenge. This process is complicated by incomplete knowledge of what actually damages the fetus prior to causing death – chronic hypoxemia, acidemia, or a combination of both – and the impact of gestational age on fetal responses to hypoxic stress. Based on our current understanding of fetal deterioration our focus lies on ‘screening’ for fetal responses to compromised oxygenation. The criteria for a successful screening test are well defined. The targeted condition must be an important health problem – at least 80% of the population should be at risk. The epidemiology, natural history and disease spectrum must be well delineated. There must be an identifiable early stage with a sufficiently long latent phase to allow intervention, which will change outcome. The employed tests should be simple, precise and applicable to the target population. The tests should be well validated with a known distribution of results and a suitable cut-off level to identify pre-disease. If a screening policy is to be finalized, there should be evidence from high-quality randomized controlled trials that the screening program is clinically, financially, socially and ethically acceptable and is effective in reducing morbidity or mortality. And there should be a plan for managing and monitoring the screening program and an agreed set of quality assurance standards. These criteria have yet to be fulfilled for any test of fetal well-being. Cardiotocography (CTG), Doppler and biophysical profile score (BPS) are the principal antenatal testing modalities. These have predominantly been compared in their ability to predict fetal compromise and optimize the timing of intervention1,2. However, the prognostic and diagnostic information gained in each testing modality is in great part independent of each other. The question that I will address here is: might it be better to combine, or integrate these modalities3?