17th World Congress on Ultrasound in Obstetrics and Gynecology Oral communication abstracts is the key to detecting major brain malformations at 11–14 weeks, including ovum-shaped skull, the presence of a midline, the lateral ventricles and a ‘butterfly’ choroid plexus. Proper training should increase the detection rate of brain malformations. OC166 Differences in leg posture between fetuses in breech and cephalic pregnancies B. F. Fong 1 , G. J. P. Savelsbergh 2 , J. I. P. De Vries 1 1 VU University Medical Centre, Department of Obstetrics and Gynaecology, Netherlands, 2 Institute for Fundamental and Clinical Human Movement Sciences (IFKB), Faculty of Movement Sciences VU, Amsterdam, Netherlands Objectives: Breech babies have a higher risk of developing hip dysplasia. To enhance our understanding of fetal leg posture development and differences between breech and cephalic born babies, we longitudinally studied the intrauterine leg position in these fetuses during the last trimester of pregnancy. This study was nested in a longitudinal study in which we also examined external influences on postural fetal arm and head development in the same groups. Methods: Leg posture was determined during 15 min of ultrasonic observations in 10 healthy breech fetuses and 10 healthy cephalic fetuses from 33 weeks’ gestational age until birth. Flexion of the knee was assessed, as well as crossing of the lower legs as a measure of hip abduction. Results: The breech fetuses showed more knee extension than the cephalic fetuses (P < 0.001). The breech fetuses showed significantly less leg crossing than the cephalic fetuses (P < 0.01) (Table). For both findings, no significant change over time was observed in either group. The table shows the mean percentage of recording time spent with crossed legs (with 95% CI) for breech and cephalic fetuses. Gestational age (weeks) Breech Cephalic 33 31 (21–41) 85 (79–91) 34 11 (1–21) 57 (45–69) 35 25 (19–31) 50 (37–63) 36 38 (29–47) 41 (28–54) 37 13 (7–20) 51 (38–64) 38 25 (14–36) 58 (43–73) 39–40 12 (4–20) 67 (51–83) Conclusions: These findings seem to provide further confirmation that intrauterine breech presentation does influence fetal postural development. The significantly smaller amount of leg crossing in the breech babies may play a role in less hip abduction and thus the observed higher risk of congenital hip dysplasia. However, because the differences could already be observed irrespective of duration of breech presentation, it seems unlikely that intrauterine movement restriction can solely be held accountable for the observed differences in leg posture between groups. OC167 Assessment of the Sylvian fissure operculization (SFO) at between 22 and 32 weeks of gestation: a subjective approach (part I) E. Quarello , J. Stirnemann, L. Guibaud, Y. Ville CHI Poissy, France Objectives: Sylvian fissure operculization (SFO) is a dynamic process throughout gestation and could be the most amenable feature to ultrasound evaluation of fetal cortex gyration. This study aimed to define a reliable score for SFO. Methods: A cross-sectional study was conducted over 9 months. Ultrasound evaluation of SFO was performed in 200 fetuses without cerebral abnormality at between 22 and 32 weeks of gestation using a standard axial plane of the fetal brain showing the override of the insula by the posterior temporal lobe. SFO was scored on a scale from 0 to 10 according to a predefined scoring-sheet based on the increase of the override of the temporal lobe with gestational age. Intra- and interobserver agreement was assessed by three evaluations performed for each case by three different operators, blinded to gestational age. Because of the nested structure of the dataset, linear mixed-effects models were used for concurrent assessment of inter- and intrarater agreement. Subject-specific variance of the score was derived for each week of gestation from the whole repeated-measures dataset and used to define a 5 th and 95 th percentile of the score (mean score week ± 1.645 SD subject, week). Results: The inter- and intraobserver agreement correlation coefficients were 0.91 (0.89 – 1) and 0.95 (0.93 – 1) respectively with a standard error of measurement of < 1 scoring unit. A reference chart was fitted, showing the increase of SFO score between 22 weeks and 32 weeks, along with age-specific 5 th and 95 th percentiles. Conclusions: A simple scoring evaluation of the SFO is a reliable method for assessing normal operculization and therefore brain maturation at between 22 and 32 weeks of gestation. OC168 Assessment of Sylvian fissure operculization (SFO) between 22 and 32 weeks of gestation: an objective approach (part II) E. Quarello 1 , J. Stirnemann 1 , M. Nassar 1 , L. Guibaud 2 , Y. Ville 1 1 CHI Poissy, France, 2 Service de Radiop´ ediatrie et d’imagerie foetale Lyon, France Objectives: The evaluation of fetal cortex gyration is an important part of ultrasound examination for suspected cerebral abnormalities. Sylvian fissure operculization (SFO) is a dynamic process throughout gestation and is among the most useful means of evaluating fetal cortex gyration. Its assessment relies mainly on a subjective interpretation. This cross-sectional study aimed to define the criteria for a rational and quantitative characterization of the SFO. Methods: From July 2006 to March 2007, one operator prospectively and routinely performed ultrasound evaluation of SFO in fetuses without cerebral abnormality at between 22 and 32 weeks of gestation. A standard view in the axial cerebral plane was defined for assessment of SFO showing the override of the insula by the posterior temporal lobe. The Sylvian fissure (a) and the posterior operculum (b) were measured in each case. The Sylvian operculization ratio (SOR) was defined as the ratio b/a. A non- parametric approach (LMS method) was used to fit reference charts for each of the three measurements. Results: Some 197 fetuses (171 singletons and 26 twins) were evaluated. Reference ranges along with 5 th , 10 th , 90 th and 95 th percentiles were calculated for each of the indices across gestational age. Conclusions: A simple quantitative assessment of SFO may be useful in low-risk patients to screen for cerebral abnormalities, and for detailed evaluation in fetuses with suspected cerebral abnormalities. OC169 Fetal cardiac volumes calculated from reconstructed and from live 3D echo B. Tutschek 1 , L. Hui 2 , P. Robertson 2 , M. Schaal 2 , M. Minette 2 , D. Sahn 2 1 Prenatal Medicine Munich, Germany, 2 Oregon Health and Science University (OHSU), Portland, Oregon, United States Objectives: In the fetus 2D echo cannot be used reliably to calculate right and left ventricular (RV, LV) chamber volumes. Previously published volumetric data using mechanical sweep systems and STIC can now be compared with 2D matrix array transducer-based 418 Ultrasound in Obstetrics & Gynecology 2007; 30: 367–455