Objectives To report the outcome of selective fetal growth restriction (sFGR) diagnosed according to the new Delphi consensus definition, and determine potential predictors of survival, in a cohort of unselected monochorionic diamniotic twin pregnancies. Methods This was a retrospective study of monochorionic diamniotic twin pregnancies followed from the first trimester onward, which were diagnosed with sFGR at 16, 20 or 30 weeks' gestation. sFGR was defined according to the new Delphi consensus criteria as presence of either an estimated fetal weight (EFW) < 3rd centile in one twin or at least two of the following: EFW of one twin < 10th centile, abdominal circumference of one twin < 10th centile, EFW discordance ≥ 25% or umbilical artery pulsatility index of the smaller twin > 95th centile. The primary outcomes were the overall survival rate (up to day 28 after birth) and risk of loss of one or both twins. We further determined possible predictors of survival using uni‐ and multivariate generalized estimated equation modeling. Results We analyzed 675 pregnancies, of which 177 (26%) were diagnosed with sFGR at 16, 20 or 30 weeks. The overall survival rate was 313/354 (88%) with 146/177 (82%) pregnancies resulting in survival of both twins, 21/177 (12%) in survival of one twin and 10/177 (6%) in loss of both twins. Subsequent twin anemia–polycythemia sequence (TAPS) developed in 6/177 (3%) and twin–twin transfusion syndrome (TTTS) in 17/177 (10%) pregnancies. All TAPS fetuses survived. The survival rate in sFGR pregnancies that subsequently developed TTTS was 65% (22/34), compared with 91% (279/308) in those with isolated sFGR (no subsequent TAPS or TTTS) (P < 0.001). The majority of sFGR cases were Type I (110/177 (62%)) and had a survival rate of 96% (212/220), as compared with a survival of 55% (12/22) in those with Type‐II (P < 0.001) and 83% (55/66) in those with Type‐III (P = 0.006) sFGR. The majority of sFGR pregnancies (130/177 (73%)) were first diagnosed at 16 or 20 weeks (early onset), with a survival rate of 85% (221/260), as compared with a survival of 98% (92/94) in sFGR first diagnosed at 30 weeks (late onset) (P = 0.04). A major anomaly in at least one twin was present in 28/177 (16%) sFGR cases. In these pregnancies, survival was 39/56 (70%), compared with 274/298 (92%) in those without an anomaly (P < 0.001). Subsequent development of TTTS (odds ratio (OR), 0.18 (95% CI, 0.06–0.52)), Type‐II sFGR (OR, 0.06 (95% CI, 0.02–0.24)) and Type‐III sFGR (OR, 0.21 (95% CI, 0.07–0.60)) and presence of a major anomaly in at least one twin (OR, 0.12 (95% CI, 0.04–0.34)), but not gestational age at first diagnosis, were independently associated with decreased survival. Conclusions Isolated sFGR is associated with a 90% survival rate in monochorionic diamniotic twin pregnancies. The subsequent development of TTTS, absent or reversed end‐diastolic flow in the umbilical artery of the smaller twin and the presence of a major anomaly adversely affect survival in sFGR. Copyright © 2020 ISUOG. Published by J...

<b><i>Background:</i></b> Evidence to support a fortnightly scan protocol for monochorionic diamniotic (MCDA) pregnancies to detect twin-twin transfusion syndrome (TTTS) is scarce. Also, TTTS-related mortality in an unselected cohort is not well documented. Finally, common knowledge suggests that a more frequent follow-up may pick up the disease at a milder stage, but little is known on the ultrasound findings before the diagnosis. <b><i>Objectives:</i></b> We examine if a fortnightly ultrasound scan from 16 weeks onward detects TTTS in time. Also, we document the outcomes in a large unselected cohort of MCDA twins and examine the ultrasound findings within 14 days before diagnosis. <b><i>Methods:</i></b> Retrospective cohort of 675 MCDA twin pregnancies followed with a fortnightly scan protocol from 16 weeks onward. Timely detection of TTTS was defined as before fetal demise (stage V), ruptured membranes, or a dilated cervix. We compared the ultrasound findings before the diagnosis between stage I–II and stage III–IV. <b><i>Results:</i></b> A total of 82/675 (12%) pregnancies developed TTTS, of which 74/82 (90%) were detected in time. In 8/82 (10%), TTTS was diagnosed in stage V: 5 before 16 weeks and 2 after 26 weeks. Fetoscopic laser photocoagulation (FLP) of the placental anastomoses was performed in 48/82 (59%). The survival of TTTS in the entire cohort was 105/164 (64%). In contrast, survival after FLP was 77/96 (80%). In 16/19 (84%) of stage III–IV TTTS, abnormal Doppler findings preceded the diagnosis of TTTS. <b><i>Conclusions:</i></b> A scheme of fortnightly ultrasound scans from 16 weeks onward detects 9 out of ten TTTS pregnancies in time. Most stage V cases presented outside the typical time window of 16 and 26 weeks. Survival rates after FLP underestimate the mortality of TTTS. Most stage III–IV cases have abnormal Doppler findings before the diagnosis of TTTS.

Virtual poster abstracts Methods: Case note review of all cases from May 2014-October 2019. Results: FLA for TTTS was performed in 46 women at 16-26 weeks gestation. The median Quintero stage at FLA was II. 38 women underwent fetal neurological MRI assessment subsequent to their laser therapy and eight women did not undergo fMRI (three patients had an intrauterine loss of both fetuses; four patients delivered prior to planned fMRI and one patient declined fMRI). Of the 38 women undertaking MRI assessments: 25 had two surviving fetuses and 12 had one surviving fetus, with a total of 63 fetuses assessed. The fMRI was performed at a median gestation 26 weeks (range 23-30 weeks) post-FLA. fMRI demonstrated macroscopic brain abnormalities in 6% (4) of imaged fetuses: mild ventriculomegally (1), reparative microgyria (2) and small volume germinal matrix bleed (1). These were likely to be sequelae of TTTS plus or minus its therapy by FLA. Conclusions: 6% of fetuses assessed by interval fetal MRI had evidence of macroscopic neurological findings on fMRI. This data supports the known literature of neurological sequelae of TTTS and antenatal imaging of these babies has allowed for tailored neurodevelopment follow-up. VP43.02 Predictive value of twins' umbilical intercord distance for complications in monochorionic twin pregnancy