20th World Congress on Ultrasound in Obstetrics and Gynecology Poster abstracts P04.02 Can single three-dimensional ultrasound volume of the fetal head be used for measurement both of the facial angle and the nuchal translucency? V. Frisova Profema – Fetal Medicine Centre, Vlasim, Czech Republic Objectives: To evaluate if a three-dimensional (3D) ultrasound volume stored for the assessment of the facial fronto-maxillary (FMF) angle can also be used for measurement of nuchal translucency (NT). To evaluate whether a single 3D ultrasound volume of the fetal head in the sagittal plane is a faster and reliable method for determining the FMF angle and NT compared with standard two-dimensional (2D) ultrasound. Methods: This was a prospective study, in which NT of 100 fetuses was measured using the standard 2D ultrasound by a single FMF certified examiner. Also 3D volumes of the fetal head sagittal orientation were acquired by the same sonographer at the time of visit and stored for further analysis. The FMF angle was measured on the 3D images at the time of screening, however NT was measured on the stored 3D volumes off-line. The ability to reconstruct mid- sagittal view and perform measurement of nuchal translucency in 3D volumes was assessed. Consequently, the measurements using a conventional 2D sagittal view and 3D reconstructed sagittal view were compared. Results: The nuchal translucencies of 100 fetuses were measured using both 2D technique and 3D multiplanar reconstruction. It was possible to measure NT in more than 90% of the stored fetal head volumes. In the paired 2D and 3D ultrasound measurements, the difference in NT measurements was less than 5% in more than 90% of the cases. The small variations between 2D and 3D measurements of NT were mainly caused by a different flexion of the fetal neck or slight deviation of the mid-line on 2D images. Conclusions: There is strong correlation between the measurements of the NT in 2D scanning and those obtained from 3D multiplanar reconstruction. Both NT and FMF angle can be easily and accurately measured on a single 3D volume of the fetal head acquired in the sagittal plane. The 3D technique seems potentially useful in fetuses that are not in an optimal position for standard 2D nuchal translucency measurement. Future research will be needed to prove this. P04.03 Frontomaxillary facial angle at 11+0 to 13+6 weeks in Chinese population M. Chen 1,2 , H. Wang 3,1 , Y. Wah 1 , T. Leung 1 , D. Sahota 1 , M. Borenstein 4 , K. Nicolaides 4 , T. Lao 1 ,T. Lau 1 1 Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Shatin, New Territories, China; 2 Department of Diagnostic Ultrasound, Shangahi 1 st Maternity and Infant Hospital, Tongji University, Shanghai, China; 3 Department of Ultrasound, the Second Clinical Medical College of Jinan University, Shenzhen People’s Hospital, Shenzhen, China; 4 Harris Birthright Research Centre for Fetal Medicine, King’s College Hospital, London, United Kingdom Objectives: To establish the normal range of frontomaxillary facial (FMF) angle in the first trimester in a Chinese population. Methods: In a prospective study from March 2007 to June 2007, three-dimensional (3D) volumes of the fetal profile in the mid- sagittal plane were recorded from 129 normal pregnancies screened for trisomy 21 by the combination of fetal nuchal translucency (NT) thickness, maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11–13+6 weeks. 3D volumes were examined using multiplanar techniques. The FMF angle of each case was measured. The relationship between the measured FMF angle with the other parameter was also examined. Results: The mean FMF angle decreased from 86.8 ◦ for a crown–rump length (CRL) of 45 mm to 76.0 ◦ for a CRL of 84 mm (FMF angle = 99.49–0.28 × CRL, P < 0.0001). The mean (SD) delta FMF angle derived from our formula, 0.07 (4.26), was significantly larger than that from the published reference equation, −1.40 (4.31) (P < 0.0001). Conclusions: In the first trimester, the FMF angle decreases with fetal CRL. There was small and clinically insignificant difference in the normal value of FMF angle between the Chinese and Caucasian population. Supporting information can be found in the online version of this abstract. P04.04 Characterizing the ‘iliac lucency’ in the first trimester R. S. Abu-Rustum 1 , M. Ziade 2 , S. E. Abu-Rustum 3 1 Center For Advanced Fetal Care, Tripoli, Lebanon; 2 Lebanese University, Tripoli, Lebanon; 3 Dept. of Ob/Gyn, Nini Hospital, Tripoli, Lebanon Objectives: To characterize a bilateral echolucent area termed ‘iliac lucency’ (IL) in the first trimester fetal pelvis. The IL may be mistaken for the fetal bladder if visualized in a parasagittal plane. Methods: Prospective study on 106 fetuses between 10w0d and 17w0d. A 3D volume of the fetal pelvis was obtained on each fetus at the level of the IL. Off line analysis was subsequently carried out. The 3D volume was standardized with the IL in the ‘a’ plane, and the reference dot placed halfway between them. Tomograpgic ultrasound imaging (TUI), with 2 mm slice thickness, was then used. The AP diameter of the bladder was measured as well as the AP diameter of the IL bilaterally. The average AP diameter of the 2 IL for each fetus was calculated. Regression analysis was used to establish the reference range and significance of the relationship of the IL to the crown–rump length. Results: The IL was visible in 103/106 fetuses (not visible in two at 10 weeks and one at 14w1d). The fetal bladder was seen in 104/106 (not visible in one at 10w4d and another 10w5d). IL ranged from 0.9 to 4.85 mm with a median of 2.3 mm. The AP diameter of the fetal bladder ranged between 0.7 to 9.4 mm with a median of 2.2 mm. Oftentimes the IL and the bladder were visualized in the same TUI plane or in 2 consecutive planes 2 mm apart. Conclusions: The IL is visible in all fetuses at the time of the first trimester scan, 11w6d–13w6d, with a median AP diameter of 2.3 mm. The median AP diameter of the fetal bladder in this study was 2.2 mm. Given its closeness in distance to the bladder, as well as in appearance and size at this point in gestation, the IL may be mistaken for the fetal bladder when viewed in a parasagittal plane. Care must be taken when attempting to complete a first trimester anomaly scan. The fetal bladder should be visualized in an axial, coronal or a true midsagittal plane, the same plane in which the nuchal translucency is measured. It may be worthwhile to evaluate the evolution of the IL in the early first and second trimester to further characterize its identity. P04.05 Physical exercise decreases the number of fetal cells in maternal blood J. M. Schl ¨ utter 1 , I. Kirkegaard 1 , B. Christensen 2 , S. Kølvraa 3 , N. Uldbjerg 1 1 Department of Gynecology and Obstetrics, Aarhus University Hospital, Skejby, Aarhus N, Denmark; 2 FCMB ApS, Vejle, Denmark; 3 Department of Clinical Genetics, Vejle Hospital, Vejle, Denmark Objectives: We have established a robust method to specifically identify and isolate a subgroup of fetal cells in maternal blood (fcmb) 180 Ultrasound in Obstetrics & Gynecology 2010; 36 (Suppl. 1): 168–305