9–12 September 2012, Copenhagen, Denmark Short oral presentation abstracts OP33.11 A new scoring system for the diagnosis of placenta accreta by ultrasound Y. Gilboa , M. Spira, E. Sivan, E. Schiff, R. Achiron OBGYN, Sheba Medical Center, Hod Hasharon, Israel Objectives: Our aim was to determine the accuracy of a novel simple scoring system based on sonographic markers in differentiating between low and high risk forplacenta accreta (PA). Methods: All women who were referred to the Sheba Medical Center due to suspected PA were included, underwent a detailed ultrasound examination. A score was given based on the common sonographic findings of PA: loss of the hypoechoic retroplacental zone and placental lacunae. A score of 0–2 was defined as low risk and 3 was defined as high risk. Patients assigned to the high risk category underwent prophylactic pelvic artery catheterization before cesarean section and embolization if needed, whereas patients in the low risk category underwent simple cesarean section. Results: 71 women were included. PA was diagnosed clinically during surgery in 28 women, of whom 31 had a score of 3, and ruled out in 43 women, of whom only one had a score of 3. The sensitivity, specificity, positive predictive value and negative predictive value of our ultrasound-based scoring system in predicting PA were 90%, 97.5%93 and 95% respectively. Conclusions: A simple scoring system based on ultrasound alone can identify accurately a high risk population for PA who can benefit from prophylactic pelvic artery catheterization and embolization. OP34: SCREENING FOR ANEUPLOIDY AND CONSULTING IN THE SECOND TRIMESTER OP34.01 Extracellular chromosome 21: derived microRNAs in maternal circulation: evaluation of their diagnostic potential for screening of Down syndrome I. Hromadnikova 1 , K. Kotlabova 1 , J. Doucha 2 , D. Chudoba 3 , P. Calda 4 , K. Dlouha 5 1 Department of Molecular Biology and Cell Pathology, Charles University, Third Faculty of Medicine, Prague 10, Czech Republic; 2 Clinic of Obstetrics and Gynecology, Charles University, Second Faculty of Medicine, Prague 5, Czech Republic; 3 Department of Biology and Medical Genetics, Charles University, Second Faculty of Medicine, Prague 5, Czech Republic; 4 Clinic of Obstetrics and Gynecology, Charles University, First Faculty of Medicine, Prague 2, Czech Republic; 5 Institute for the Care of the Mother and Child, Prague 4, Czech Republic Objectives: In this pilot study we focused on the detection of extra- cellular microRNAs in maternal circulation, whose genes are located on human chromosome 21 (miR-99a, let-7c, miR-125b-2, miR-155 and miR-802). Subsequently, we studied if plasmatic concentrations and/or expression profile of extracellular chromosome 21-derived microRNAs would distinguish between pregnancies bearing euploid foetuses and those affected with Down syndrome. Methods: 12 women with normal course of gestation (mean 16.4 weeks, median 16.0 weeks), 12 pregnancies bearing Down syndrome foetus (mean 18.2 weeks, median 18.5 weeks) and 6 non-pregnant individuals were involved in the retrospective study. RNA enriched for small RNAs (including microRNAs) was isolated from 1 ml of plasma sample. Consequently relevant microRNA was transcribed into cDNA using specific stem-loop primer and detected by specific real-time PCR assay. Results: Commercial systems enabled reliable detection of 4 out of 5 extracellular chromosome 21-derived microRNAs (miR-99a, let-7c, miR-125b-2 and miR-155). Expression profile of extracellular miR- 99a, miR-125b-2 and miR-155 was significantly higher in the cohort of pregnant women than in non-pregnant individuals. Also plasmatic levels of miR-99a and miR-125b-2 were significantly increased in pregnant women. Unfortunately, the concentrations and gene expression of extracellular chromosome 21-derived microRNAs (miR-99a, let-7c, miR-125b-2 and miR-155) did not differ between the cohorts of pregnancies bearing euploid foetuses and those affected with Down syndrome. Conclusions: Analysis of extracellular chromosome 21-derived microRNAs does not distinguish between pregnancies with euploid and aneuploid foetuses and has no benefit for screening programmes. Acknowledgement: The work was supported by GAUK no. 434011. OP34.02 Ultrasound screening of Down-syndrome in the second trimester: the prenasal thickness alone J. Szab ´ o 1 , A. Szab ´ o 1 , K. Szili 1 , J. Szab ´ o 2 , D. Isaszegi 1 , E. Horv ´ ath 1 , J. Sikovanyecz 2 1 Department of Medical Genetics, University of Szeged, Szeged, Hungary; 2 Department of Obstetrics and Gynecology, University of Szeged, Szeged, Hungary Objectives: Down-syndrome screening in first trimester based on increased nuchal translucency (NT) and biochemical markers is very effective. However, in second trimester it is a great challenge in the absence of efficient ultrasound marker. During the last years several reports suggested that prenasal soft tissue thickness and nasal bone hypoplasia could be sonographic markers for Down-syndrome screening. We measured and compared the prenasal thickness (PT) in euploid and in fetuses with Down-syndrome prospectively. Methods: Transabdominal 2D ultrasound (Voluson E8) measure- ment of the prenasal thickness was performed in mid-sagittal plane of the fetal head identifying diencephalon, tip of the nose, lips, maxilla, nasal bone. The insonation angle was 90 ◦ to the nasal bone or maximum 30 degree of lifting to the frontal bone was allowed. The prenasal thickness was defined as the shortest distance from the lower edge of the os frontale to the outer surface of the overlying skin. The nasal bone can also be determined from this view. The magnification of the view (zoom) was zoomed such that the fetal profile occupied the whole screen. Results: We analyzed the results of 810 euploid and 19 fetuses with trisomy 21 measured between the 16–23 gestational weeks. In euploid fetuses the mean PT (and NBL) increased steadily between 16 and 33 weeks’ gestation. The difference in the median PT values between the two groups was greater than it would be expected by chance. There was a statistically significant difference (P < 0.001) according to Mann-Whitney Rank Sum Test. All of the 19 fetuses with trisomy 21 the PT values were lower than 5 th percentile curve of the euploid group. Conclusions: The ultrasound measurement of prenasal soft tissue thickness was found to be highly efficient marker alone for trisomy 21. The Down-syndrome screening with this marker can become more effective. OP34.03 Prenasal thickness, nasal bone length and their ratio: good second trimester sonographic markers for Down syndrome A. Szab ´ o 1 , K. Szili 1 , J. Szab ´ o 2 , D. Isaszegi 1 , E. Horv ´ ath 1 , J. Sikovanyecz 2 , J. Szab ´ o 1 1 Department of Medical Genetics, University of Szeged, Szeged, Hungary; 2 Department of Obstetrics and Gynecology, University of Szeged, Szeged, Hungary Objectives: Down syndrome screening in first trimester based on nuchal translucency (NT) and biochemical markers is very efficient, while in second trimester it is a great challenge. Measurement of nasal bone length and prenasal soft tissue thickness was found to be promising facial landmarks in second trimester screening Ultrasound in Obstetrics & Gynecology 2012; 40 (Suppl. 1): 55–170 157