13 th World Congress on Ultrasound in Obstetrics and Gynecology Oral communication abstracts (PRUV) according to the described subtypes: 1. Intrahepatic form; 2. the form in which umbilical vein is directly connected to inferior vena cava or right atrium or iliac vein; 3. the form in which both umbilical veins persist. Material and methods: Between January 1996 and December 1999, unselected patients were prospectively evaluated at our Department. The sonographic diagnosis of PRUV (intrahepatic variant) was made in transverse section of the abdomen when the following criteria were met: 1. The portal vein curved towards the stomach 2. The umbilical vein was abnormally connected to the right portal vein instead of to the left portal vein 3. The fetal gallbladder was located medially to the umbilical vein apparently left sided. Longitudinal and coronal planes (B mode, Color Doppler) were also used to assess the venous system connections and to diagnose the other two variants. Results: PRUV was observed in 25 cases with a prevalence in our study of 0.47% (1/214). The intrahepatic variant was detected in 23 cases: no associated malformations and/or unfavourable outcome was found in 22 cases. One case was associated with single umbilical artery and the fetus subsequently developed growth restriction. One case of PRUV with umbilical vein directly connected to inferior vena cava (type 2) was associated with destrocardia: no additional malformations were found at birth. Discussion: Recent studies and our experience support that the intrahepatic variant seems to be a fairly common condition, mostly observed as an isolated finding with a good prognosis. However associated malformations may occur especially involving the cardiovascular system. The incidence of the other two forms is difficult to estimate considering the high rate of association with complex malformations. OC239 Invasive and non-invasive prenatal diagnosis in pregnancies following assisted reproduction techniques A. Geipel *, C. Berg*, A. Katalinic†, M. Ludwig‡, U. Germer§, K. Diedrich§ and U. Gembruch* *University Hospital of Bonn, Germany; †Institute of Cancer Epidemiology, L ¨ ubeck, Germany; ‡Center for Reproductive Medicine, Hamburg, Germany and §University Hospital of L¨ ubeck, Germany Objective: The impact of targeted first and second trimester ultrasound on the decision regarding invasive testing was examined in pregnancies achieved by assisted reproduction compared to spontaneous conception. Methods: Retrospective analysis of 436 singleton and 146 twin pregnancies following assisted reproductive technologies (ART). As controls, spontaneous conceptions were matched for maternal age, parity and number of fetuses. First trimester screening included risk assessment by maternal age and nuchal translucency measurement. The second trimester sonogram incorporated detailed fetal examination with echocardiography and screening for specific markers of fetal aneuploidy. Results: The mean maternal age was 32.7 + 4.1 years. The mean number of ultrasound examinations was significantly higher in ART pregnancies (1.9 + 1.8) compared to controls (1.8 + 0.7). Karyotyping was performed significantly more frequently in spontaneously conceived pregnancies (24.0%) compared to the ART group (16.1%) (p < 0.01). Following a normal ultrasound result, only 23.8% of ART patients > 35 years opted for invasive testing, compared to 46.0% in spontaneously conceived pregnancies (p < 0.01). Fetal aneuploidy was diagnosed in 1.2% of ART pregnancies and 1.7% of controls. Conclusion: Individual risk modification by ‘‘genetic sonography’’ improves selection criteria for invasive testing and is preferred by the majority of patients with pregnancies following ART. OC241 Treatment of twin-to-twin-transfusion syndrome. The end of a long-standing misunderstanding Y. Ville * for the Eurofoetus group *Facult´ e de Medecin Paris-Ouest, France Twin-to-twin-transfusion syndrome before 26 weeks carries a poor prognosis with only 10–15% survival and severe handicap in 25–30% of the survivors. Multicentre open randomized controlled study comparing amnio- drainage and laser treatment of severe forms of twin-to-twin- transfusion syndrome presenting before 26 weeks of gestation. Between 1999 and 2002, 143 patients were included in the trial with 71 cases in the laser group and 72 cases in the amniodrainage group. Survival, gestational age at delivery and birthweight were significantly higher in the laser group. There was also less periventricular leukomalacia in the laser group. This study establishes laser treatment of placental anastomoses is the most efficient therapy in this disease. OC242 Neurodevelopmental outcome after intrauterine laser coagulation of vascular anastomoses in severe twin-twin transfusion syndrome K. Hecher , C. S. Banek, B. Ellenrieder, C. Gr¨ af, A. Huber, B. J. Hackel ¨ oer and P. Bartmann AK Barmbeck, Hamburg, Germany Objective: To investigate long-term neurodevelopmental outcome after intrauterine laser treatment for severe twin-twin transfu- sion syndrome. Methods: We compared outcome of the first group of 89 survivors (Am J Obstet Gynecol 2003; 188: 876 – 80) with the following group of 167 children. All infants underwent a detailed standardized physical and neurological examination and were tested with the Griffiths’ Developmental Test Scales or the Snijders-Oomen-Non- Verbal-Intelligence Test. Results: In the first group, 78% (n = 69) showed a normal development, 11% (n = 10) had minor and 11% (n = 10) major neurologic deficiencies. In the second group, 87% (n = 145) showed a normal development, 7% (n = 12) had minor and 6% (n = 10) major neurologic abnormalities. Conclusions: Compared with the literature on outcome after serial amniodrainages, this study shows a high rate (overall 84%) of normal neurodevelopmental outcome and a relatively low rate (overall 8%) of major neurologic abnormality in children who were treated by intrauterine laser coagulation. OC243 Is discordant fetal growth in monochorionic multiple gestations a surgical condition? R. A. Quintero FL Institute for Fetal Dx and Rx, USA Objective: Selective intrauterine growth retardation (SIUGR) is associated with increased perinatal morbidity and mortality. Spontaneous demise of the SIUGR twin (IUFD-SIUGR) may result in concomitant demise of the appropriately grown (AGA) twin (40%), or in neurological handicap (30%). The adverse effects of the IUFD- SIUGR are mediated by peri-mortem feto-fetal hemorrhage from the AGA to the SIUGR twin through patent placental vascular communications. While the surgical technique to occlude all vascular anastomoses in a monochorionic twin gestation has been perfected, the optimal management strategy for patients with SIUGR is 64 Ultrasound in Obstetrics & Gynecology 2003; 22 (Suppl. 1): 1–69