355: sIUGR in monochorionic diamniotic twins: Is it discordance >25%, EFW < 10th percentile or both?

Abstract

Selective intrauterine growth restriction (sIUGR) is a common but inconsistently defined complication of monochorionic diamniotic (MCDA) twins. We sought to compare two definitions of sIUGR: 1) Estimated fetal weight (EFW) discordance > 25th percentile plus EFW < 10th percentile in the smaller twin. 2) Only one of these criteria. This is a retrospective cohort study of MCDA twin gestations that had surveillance ultrasounds (US) at our center between 2012 and 2018. We compared sIUGR pregnancies with EFW discordance > 25th percentile plus EFW < 10th percentile for the smaller twin (Group 1) to those with only one of these criteria (Group 2). Women with uncertain chorionicity, twin to twin transfusion syndrome, fetal anomalies, or less than 4 serial US exams were excluded. Routine US was performed biweekly from 16 weeks gestational age (GA) until delivery. The primary outcome was composite perinatal morbidity and mortality (Table 2). Pregnancy characteristics including Gratacos type, indication for delivery and mode of delivery were also compared between groups. Of 293 MCDA pregnancies that met inclusion criteria, sIUGR developed in 66 (22.5%); 42 women followed at our center for the entire pregnancy. Among these women, 18 (42.8%) were in Group 1 and 24 (36.4%) were in Group 2 (8 with discordance > 25%, 16 with EFW < 10th percentile). Maternal age, race, parity, and BMI were similar between groups (Table 1). Women in Group 1 were diagnosed with sIUGR at an earlier GA (22.2 [18.3, 27.0] vs. 28.6 [25.0, 32.0] weeks, p = 0.004). They were also more likely to have Gratacos type II or III (50.0% vs. 4.2 %, p = 0.001) and deliver due to deterioration of fetal status (55.6% vs. 4.2%, p = 0.001). The composite outcome occurred more frequently in Group 1 (44.7% vs. 13%, p = 0.001). sIUGR neonates with discordance of EFW > 25th percentile plus EFW < 10th percentile have more perinatal complications than those with only one criterion. Increased US surveillance may be beneficial in these pregnancies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)