16th World Congress on Ultrasound in Obstetrics and Gynecology Oral communication abstracts OC66 Detection of twin–twin transfusion syndrome L. Sperling 1 , L. U. Larsen 2 , I. Qvist 3 , C. Jorgensen 1 , A. Tabor 1 1 Department of Fetal Medicine, Rigshospitalet, Copenhagen, Denmark, 2 University Hospital Aarhus, Denmark, 3 University Hospital Aalborg, Denmark Objective: The aim of this study was to evaluate the outcome of screening for twin-to-twin transfusion syndrome (TTTS) among monochorionic (MC) twins through a number of scans from 12 weeks of gestation. Methods: In a prospective multicenter observational study twin pregnant women were included before 14 + 6 weeks. The MC pregnancies were scanned every second week until 23 weeks of gestation in order to rule out early TTTS. Further observation during pregnancy was done according to the departments’ guidelines. Zygosity was analysed by DNA analysis in all twin pairs with the same sex. All the participants were contacted eight months or more after delivery. Results: Among the 495 twin pregnancies 15% were MC. The incidence of TTTS was 23% from 12 weeks until delivery. In 15 out of 17 twin pregnancies signs of the TTTS syndrome were seen before 24 weeks and all those MC twin pregnancies who miscarried had signs of TTTS. None of the NT measurements in these fetuses were above the 95 TH centile. There was no difference in NT-discordance rate between MC twins with TTTS compared to MC twins without signs of TTTS. Conclusion: Assessment of chorionicity and follow-up of mono- chorionic pregnancies to detect signs of TTTS are essential in order also to treat early stages of TTTS. It was not possible by nuchal translucency measurement to detect those MC pregnancies that later developed TTTS. OC67 Classification of selective intrauterine growth restriction in monochorionic twins according to umbilical artery Doppler of the smaller fetus E. Gratacos 1 , L. Lewi 2 , B. Munoz 3 , E. R. Acosta-Rojas 1 , J. M. Martinez-Crespo 1 , E. Carreras 3 , J. Deprest 2 1 Hospital Clinic-IDIBAPS, University of Barcelona, Spain, 2 University Hospital Gasthuisberg, Leuven, Belgium, 3 University Hospital Vall d’Hebron, Barcelona, Spain Objective: To evaluate the association with the clinical outcome and the pattern of inter-fetal anastomoses of a classification of selective intrauterine growth restriction (sIUGR) in monochorionic twins (MC) based on the characteristics of umbilical artery Doppler (UA) in the smaller twin. Methods: 103 cases with sIUGR at 18–26 weeks were classified as type I (UA with positive diastolic flow, n = 22), type II (absent or reversed end diastolic flow (AREDF), n = 28), and type III (intermittent absent or reversed end diastolic flow (iAREDF), n = 53) and compared with 64 uncomplicated MC. Perinatal outcome, placental sharing and the pattern of anastomoses were evaluated. Results: Type II and III pregnancies delivered significantly earlier than type I and consequently fetal birth weights were also lower. Fetal weight discordance was significantly higher in type II and III in comparison with type I. Fetal deterioration of the IUGR fetus before 28 weeks occurred in 90% of type II cases, compared with 0% and 8.3% in types I and III respectively (p < 0.01). Sudden intrauterine fetal death of the smaller twin occurred in 20.3% in type III cases, compared with 4.5% and 0% in types I and II respectively (p < 0.01). Parenchymal brain lesions were observed in 18% of the larger twins in type III pregnancies, while in the rest of neonatal subgroups it was below 5% (p = 0.03). The anastomotic pattern differed significantly for each subgroup. Aside from other differences, in terms of large arterio-arterial anastomoses, uncomplicated MC and type I cases had a similar distribution (58% and 67% respectively), whereas these were virtually absent in type II (3%) and virtually constant in type III (96%). Conclusion: SIUGR can be classified in 3 types that correlate with different clinical behavior and different patterns of placental anastomoses. This classification may be of help in clinical decisions and in comparisons among clinical studies. OC68 Perinatal outcome in monochorionic twin pregnancies presenting with incomplete diagnostic criteria for twin–twin transfusion syndrome M. Nassar , B. Nasr, J. Stirnemann, Y. Ville Centre Hospitalier Intercommunal de Poissy Saint Germain en Laye, France Objectives: The diagnosis of twin-to-twin transfusion syndrome (TTTS) relies on strict diagnostic criteria. Expectant management is otherwise usually advised. We aimed to assess fetal and perinatal outcome in monochorionic diamniotic (MCDA) twin pregnancies with discordant amniotic fluid volume, intrauterine growth discordance and/or Doppler abnormalities. Methods: Review of all cases referred with a diagnosis of TTTS for laser surgery between 01/2004 and 01/2006. Those that did not meet the criteria for treatment were offered weekly ultrasound follow-up. These cases were categorized as having normal Doppler (group 1) or absent or reversed end-diastolic (ared) flow in the umbilical arteries in any of the twins (group 2). Results: 302 cases of TTTS were referred for laser surgery. 40 cases (13.3%) presenting at 22.5 (range, 15–28) weeks of gestation were declined fetal surgery including 27 and 13 cases with normal and abnormal Doppler respectively. Two cases were lost for follow-up in both groups. Intra uterine growth restriction of one twin was present in 9/27 and in all 13 cases in groups 1 & 2 respectively. None of the 38 cases developed severe TTTS. No fetal intervention was indicated in group 1 and selective cord coagulation was performed in one case in group 2. Overall survival and survival of both twins were higher in group 1 [48/50 (96%) and 24/25 (96%)] than in group 2 [11/22 (50%) and 1/11 (9%)] (p < 0.0001). Gestational age at delivery was higher in group 1 (33 [26–37] vs. 31 [27–34] weeks, p = 0.06). Perinatal mortality and morbidity included 6 cases of spontaneous fetal death and 4 cases of cystic periventricular leukomalacia in the survivors, all in group 2. Conclusion: In discordant MCDA pregnancies before 26 weeks, the prognosis was based on umbilical Doppler in the smaller twin. In cases with ared flow, dismal spontaneous prognosis would justify a randomized trial to compare placental surgery or selective cord coagulation with expectant management. OC69 Percent absent end-diastolic velocity in the umbilical artery as a predictor of fetal demise of the donor twin after laser therapy in twin–twin transfusion syndrome E. V. Kontopoulos 1 , R. A. Quintero 1 , R. Chmait 2 , P. W. Bornick 3 , M. Allen 3 1 University of South Florida, United States, 2 University of Southern California, United States, 3 Tampa General Hospital, United States Objective: Absent end-diastolic in the umbilical artery of the donor twin (AEDV) is a known risk factor for intrauterine fetal demise of this fetus (IUFD-D) after selective laser photocoagulation of communicating vessels (SLPCV) for twin–twin transfusion syndrome (TTTS). The purpose of this study was to assess the percent time spent in AEDV as a predictor of IUFD-D. Study Design: All patients referred for possible SLPCV underwent complete staging evaluation including Doppler assessement of the 378 Ultrasound in Obstetrics & Gynecology 2006; 28: 359–411