1107: Prediction of outcomes after laser for TTTS with selective growth restriction using different diagnostic criteria

Abstract

Selective fetal growth restriction (sFGR) complicating twin twin transfusion syndrome (TTTS) is associated with increased risk of fetal demise after fetoscopic laser surgery (FLS). Identifying these patients is challenging due to varying definitions used in the literature. Our objective was to determine the association of three currently used definitions for sFGR with demise of the smaller twin, typically the donor, following FLS Prospective cohort of monochorionic diamniotic pregnancies undergoing FLS for TTTS between January 2015 to December 2018. Three groups were identified: A - sFGR defined by International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) as estimated fetal weight (EFW) of either twin < 10thcentile and intertwin discordance > 25%. B - based on Delphi methodology EFW of either twin < 3rdcentile. C – based on Delphi method, presence of 2 of the 4 criteria: EFW of either twin < 10thcentile, abdominal circumference of one twin < 10thcentile, EFW discordance of ≥25%, and umbilical artery pulsatility index of smaller twin > 95thcentile. Pearson chi square, logistic regression analyses were performed. FLS was performed in 139 cases. sFGR noted in 52/139 (37.4%), 65/133 (46.8%) and 78/136 (56.1%) for groups A, B and C respectively. Donor demise after FLS in sFGR vs non sFGR in group A was 26.9% vs 6.9%, p= 0.01, group B 21.5% vs 5.9%, p < 0.01, group C 23.1% vs 3.4%, p < 0.01. In group A, donor demise increased if there was sFGR in cases of stage 3 TTTS (p=0.01). There was no difference in donor demise based on stage of TTTS in groups B and C (p=0.59 and 0.82). The odds ratio of donor demise after FLS was higher in group 3 (8.4, 95% CI 1.86-37.85,p < 0.01) compared to the other groups and staging of TTTS. Fetal demise following FLS is increased in the presence of sFGR, regardless of methodology used to define it. After adjusting for gestational age at intervention and stage of TTTS, Delphi 2 of 4 criteria, had the best predictive value for post FLS fetal demise. Improving diagnosis of sFGR, will improve counseling and may affect management.