Introduction: Data on the outcomes of early-onset twin-twin transfusion syndrome (TTTS), diagnosed before 18 weeks gestational age (GA), are sparse. We aimed to review the diagnosis, management and outcomes of early-onset TTTS. Material and methods: Pregnancy records at a single referral unit 2010-6 were reviewed. In early-onset TTTS cases, data for pregnancy characteristics, interventions and outcomes were collected. PubMed and Scopus databases were searched for studies including pregnant women with early-onset TTTS. The primary outcome measure was livebirths. Results: Case series: 58 cases of early-onset TTTS 2010-6, with full outcome data in 44. Diagnostic criteria were variable. Median GA at intervention was 17 +4 (range 15 +0 -28 +1 ); 67% of patients had laser therapy (39/58). Overall survival: 60% (53/88). At least one livebirth: 86% (38/44), Two livebirths: 34% (15/44); No survivors: 14% (6/44). GA at delivery was 32 +1.5 (range 16 +2 -37 +4 ). Systematic review: 16 studies included (n = 171 pregnancies). Diagnostic criteria varied widely: 79% of studies used Quintero staging. Most offered laser (89%) at median 17 +0 weeks (range 16 +0 -21 +6 ). GA at delivery was 23 +0 -39 +5 weeks. Overall survival: 69% (129/186). At least one livebirth: 74% (127/171). Two livebirths: 59% (55/93). No survivors: 26% (44/171). Conclusions: In comparison with the commonly accepted overall survival for TTTS treated after 18 weeks of 60-90%, outcomes in early-onset TTTS were at the lower bound of this range. Gestational age at intervention is similar to that of later onset TTTS, indicating a lack of therapeutic options when a diagnosis is made before 18 weeks.

Objectives: Data on the characteristics, course and outcomes of early-onset TTTS is sparse and management options are limited at early gestations. We aimed to conduct a retrospective case series of MCDA twin pregnancies complicated by TTTS before 18 weeks gestation at a single tertiary unit. Methods: We performed a retrospective case note review of MCDA twin pregnancies with early onset TTTS (n=101) between 2010 -February 2016. We recorded data for pregnancy characteristics at diagnosis and intervention and data for antenatal, perinatal and maternal outcomes. We analysed our data divided into early, mid and late second trimester groups based on gestational age (GA) at onset of TTTS. Results: The mean absolute DVP difference was significantly smaller (p <0.05) for the early group (4.9±1.1cm) compared to the late group (7.2±2.7cm). AC ratio was similar across groups. Average GA at diagnosis was 15+3(15+0-15+6) for the early, 17+0(16+0-17+6) for the mid and 19+4(18+0-21+0) for the late groups. Median GA at delivery was 31+1(range 23+6-33+2), 33+2(range 16+2-37+4) and 32+2(range 18+1-36+0) for early, mid and late groups respectively. 57% of the early group had laser at a median GA of 17+4(±3d), 70% of the mid group at 17+5(±1d) and 72% of the late group at 20+0(±1d). Of the 70 pregnancies with outcome data overall survival was 42%. 37% of pregnancies had two livebirths, 84% had at least one livebirth leaving 16% with no survivors. Caesarean section rate for the 38 pregnancies with mode of delivery data was 74% overall, increasing from 60% to 67% to 87% for early, mid and late groups respectively. Conclusions: A significant proportion of TTTS is diagnosed before 18 weeks. There is a potential inadequacy of current diagnostic criteria, specifically for very early onset TTTS, where DVP differences are smaller and Doppler assessment is less standardised. Early onset TTTS pregnancies deliver earlier with smaller donor weights underlying the need for interventions that might be used at earlier gestation. Objectives: Current management protocols for TTTS are optimised for twins at 18-24 weeks gestational age (GA), however, up to 25% of cases of TTTS may be diagnosed <18 weeks GA. Methods which could be used prior to fusion of amnion and chorion are needed. OP26.02We systematically reviewed the published literature on diagnosis, management and outcomes of TTTS diagnosed at <18 weeks GA. Methods: PubMed and Scopus databases were searched for articles regarding early onset TTTS, from inception to April 2016. All studies types with primary data on TTTS <18 weeks GA in MCDA pregnancies were included. Exclusion criteria included studies not in English, higher order pregnancies, and diagnosis >18 weeks. Studies were independently assessed for inclusion by two reviewers. Authors of those with incomplete data were contacted. Data was extracted for study characteristics, interventions and outcomes and entered into an Excel spreadsheet and outcomes analysed. Results: 16 studies included for analysis assessed 171 pregnancies. Earliest...