27th World Congress on Ultrasound in Obstetrics and Gynecology Short oral presentation abstracts of amniotic ﬂuid and abnormal protruding mass on the lower abdominal wall was additionally detected by 3D. In the case of hymen polyp with hymenal atresia, the polyp pedunculated to hymen was clearly detected by 3D. In the case of perineal lipoma with aproctia, the lack of ‘‘target sign’’ detected by 2D was one of the clues for the diagnosis. Conclusions: In the cases with ambiguous fetal sex and/or abnormal appearance of the external genitalia, 3D ultrasonography, enabling to depict a superﬁcial stereoscopic abnormal appearance including external genitalia, is helpful to diagnosis DSD in utero. OP12.08 Prenatal diagnosis of urinary tract anomalies: a cohort study in the northern Netherlands M. Bakker 1,3 , J. Bergman 3 , H. Fleurke-Rozema 1 , E. Streeﬂand 1 , V. Gracchi 4 , C.M. Bilardo 2 , H. De Walle 3 1 Obstetrics and Gynecology, University Medical Centre Groningen, Groningen, Netherlands; 2 Fetal Medicine, University Medical Centre, Groningen, Netherlands; 3 Genetics, University Medical Centre Groningen, Groningen, Netherlands; 4 Pediatric Nephrology, University Medical Centre Groningen, Groningen, Netherlands Objectives: Urinary tract (UT) anomalies are among the most frequent congenital anomalies. Since 2007, an anomaly scan at 19-22 weeks gestation is offered to all pregnant women in the Netherlands. The aim of this study is to describe prevalence, time of diagnosis and type of birth in children and fetuses affected with UT anomalies after the introduction of the anomaly scan. Methods: We selected children and fetuses with an UT anomaly from a population-based congenital anomaly registry. Cases were deﬁned according to type of UT anomaly (anomalies of the renal parenchyma, anomalies of the collecting system, other UT anomalies) and whether isolated or with associated anomalies. For each case, information was collected on time of diagnosis and on pregnancy outcome (live birth, fetal death or termination of pregnancy). Results: A total of 487 cases (2.1:1 male to female ratio) were included, with a total prevalence of 40.8 per 10,000 births. An increase in total prevalence from 34.0 per 10,000 births in 2008 to 42.3 per 10,000 births in 2014 was observed, mainly caused by an increase in prevalence of anomalies of the collecting system. Almost 70% of cases presented as isolated. Anomalies of the renal parenchyma were more often associated with genetic disorders or other anomalies (47.3%) than anomalies of the collecting system (19.0%). The majority of cases were diagnosed prenatally, 62.5% before 24 weeks and 12.5% (mainly anomalies of the collecting system) thereafter. The proportion of prenatally diagnosed cases increased from 59.3 % in 2008 to 80.9% in 2014. Termination of pregnancy occurred in 72 cases (14.8%), in 53 of these cases (73.6%) the UT anomaly was associated with a genetic disorder or other anomalies. There was no trend pregnancy terminations. Conclusions: After the introduction of the anomaly scan we observed an increasing prevalence of UT anomalies, mainly of the collecting system. Although more UT anomalies were diagnosed prenatally over time, we observed no increase in termination of pregnancies. OP12.09 Ultrasound markers predicting complex gastroschisis and adverse outcome: a longitudinal prospective nationwide cohort study C.C. Lap 5 , A. Hijkoop 3 , L. Pistorius 7 , E.J. Mulder 5 , T.E. Cohen-Overbeek 3 , M. Aliasi 5 , W. Kramer 8 , C. Bax 1 , R. van Baren 11 , C.M. Bilardo 6 , H. Brouwers 9 , P. Dijk 10 , E. Pajkrt 1 , A. van Kaam 12 , E. Sikkel 13 , A. van Heijst 14 , M. van der Hoeven 15 , E. van Heurn 16 , C. Sleeboom 16,17 , D. Tibboel 18 , M. Weissenbruch 19 , R. Wijnen 20 , C. Willekes 4 , G. Visser 5 , G. Manten 2 1 Obstetrics, Academic Medical Centre, Amsterdam, Netherlands; 2 Woman and Baby, University Medical Centre Utrecht, Utrecht, Netherlands; 3 Obstetrics and Gynecology, Erasmus University Medical Centre, Rotterdam, Netherlands; 4 Obstetrics and Gynecology, MUMC, Maastricht, Netherlands; 5 Obstetrics and Gynecology, University Medical Centre Utrecht, Utrecht, Netherlands; 6 Fetal Medicine, University Medical Centre, Groningen, Netherlands; 7 Obstetrics and Gynecology, University of Stellenbosch, Panorama, South Africa; 8 Pediatric Surgery, University Medical Centre Utrecht, Utrecht, Netherlands; 9 Department of Neonatology, University Medical Centre Utrecht, Utrecht, Netherlands; 10 Department of Neonatology, Beatrix Children’s Hospital, University Medical Centre Groningen, Groningen, Netherlands; 11 Department of Pediatric Surgery, Beatrix Children’s Hospital, University Medical Centre Groningen, Groningen, Netherlands; 12 Department of Neonatology, Emma Children’s Hospital, Academic Medical Centre Amsterdam, Amsterdam, Netherlands; 13 Department of Obstetrics and Gynecology, Radboud University Medical Centre Nijmegen, Nijmegen, Netherlands; 14 Department of Neonatology, Radboud UMC, Nijmegen, Netherlands; 15 Department of Neonatology, Maastricht University Medical Centre, Maastricht, Netherlands; 16 Pediatric Surgical Centre of Amsterdam, Emma Children’s Hospital University Medical Centre, Amsterdam, Netherlands; 17 VU University Medical Centre Amsterdam, Amsterdam, Netherlands; 18 Intensive Care, Erasmus MC Sophia Children’s Hospital, Rotterdam, Netherlands; 19 Department of Neonatology, VU University Medical Centre Amsterdam, Amsterdam, Netherlands; 20 Department of Pediatric Surgery, Erasmus MC Sophia Children’s Hospital, Rotterdam, Rotterdam, Netherlands Objectives: To identify antenatal ultrasound markers differentiating between complex and simple gastroschisis and to investigate which variables are related to morbidity after birth. Methods: Serial longitudinal ultrasound examinations at four-weekly intervals between 20 and 37 weeks were performed in isolated fetal gastroschisis cases. The primary outcome was simple or complex (bowel atresia, volvulus, perforation or necrosis) gas- troschisis. Biometry, polyhydramnios, intra- and extra-abdominal bowel diameters and the Pulsatility Index (PI) of the superior mesenteric artery (sma) were assessed and compared to reference ranges. Linear mixed modelling was used to compare the individual trajectories of both simple and complex cases. Results: 101 cases of isolated fetal gastroschisis were included. Three intra uterine deaths occurred. Seventy-nine (80.6%) liveborn infants had simple and 19 (19.4%) had complex gastroschisis. There were 2 neonatal deaths in the complex and one in the simple group. TFEF and LOS were signiﬁcantly longer in the complex cases compared to the simple group (P<0.001, and P<0.001, respectively). There was no correlation between fetal biometry and complex gastroschisis. The PI of the intra- and extra-abdominal sma was signiﬁcantly lower than controls but did not differentiate between simple and complex cases. Both intra- and extra-abdominal bowel diameter were larger in complex cases and multilevel analysis showed a signiﬁcant group main effect for both variables (P<0.001  The Authors 2017 86  Ultrasound in Obstetrics & Gynecology 2017; 50 (Suppl. 1): 48–153.