OP16.04: Perinatal outcomes of selective fetal growth restriction in monochorionic pregnancies diagnosed with different criteria: ISUOG versus Delphi criteria

To evaluate the outcomes of fetuses diagnosed with sFGR using different diagnostic criteria. This is a cohort study of MCDA twin pregnancies. Cases diagnosed with Twin–twin transfusion syndrome (TTTS) before sFGR, or TAPS, or fetal anomalies were excluded. All twins were assessed using twin growth charts, and were diagnosed with sFGR using either ISUOG or any Delphi criteria. We compared perinatal outcomes between cases diagnosed with different criteria and uncomplicated twin pregnancies using non-parametric tests. 220 MCDA twin pregnancies were included in the final analysis, of which 45 were complicated by sFGR. Applying ISUOG criteria, 11.4% of cases were diagnosed as sFGR, whereas Delphi classified as sFGR 20.4% of all pregnancies (p = 0.009). Small fetuses diagnosed with either ISUOG or Delphi criteria had significantly higher rates of perinatal morbidity and mortality compared to controls (p < 0.05). Adjunctive analysis showed that also single diagnostic criteria (EFW< 3rd centile, EFW< 10th centile, 25% growth discordance) identified fetuses at significantly higher risk of adverse perinatal outcomes compared to uncomplicated cases. The analysis of all sFGR cases showed that Delphi criteria increased the diagnostic rate by 9%, however twins diagnosed with one of these criteria but not with ISUOG had better outcomes than those diagnosed with ISUOG (livebirth rate 92.5% vs 74%, p = 0.02; GA at delivery 33.0 ± 4.2 vs 30.9 ± 5.0, p = 0.02, composite adverse perinatal outcome 32.5% vs 58%, p = 0.02; length of stay in NICU in days 19.9 ± 16.5 vs 41.6 ± 43.2, p = 0.02). Both ISUOG and Delphi criteria identify fetuses at higher risk of perinatal morbidity and mortality compared to uncomplicated twins. Delphi criteria increased the diagnostic rate of sFGR but included cases at lower risk of adverse outcomes. Beyond those identified with an EFW < 3rd centile, there was no notable escalation in the prevalence of severe neonatal morbidity or mortality amongst those extra cases recognised when compared to the traditional definition.