15 th World Congress on Ultrasound in Obstetrics and Gynecology Poster abstracts placental volume was acquired. Afterwards, the 3D power Doppler histogram was used to analyze with computer algorithms to form vascular indices: vascularization index (VI), flow index (FI) and vascularization-flow index (VFI). These indices were registered and compared in both groups. Results: All vascular indices but FI were significantly reduced in pregnancies complicated by absent diastolic flow in umbilical arteries than in controls. < Pregnancies with AUDF Normal pregnancies p VI 3.94 (1.2–7.31) 14.88 (6.76–31.82) < 0.001 FI 38.18 (29.99–43.01) 40.77 (35.93–43.75) NS VFI 1.49 (0.46–2.68) 6.39 (2.62–10.88) < 0.001 Conclusion: Placental vascularization is significantly reduced in pregnancies complicated with absent umbilical diastolic flow, which can be demonstrated quantitatively by three-dimensional power Doppler ultrasonography. P10.12 Fetal renal blood flow velocimetry in patients with idiopathic oligohydramnios M. Treger, M. Mazor, E. Offer, E. Maymon, A. Bashiri, R. Hershkovitz Soroka University Medical Center, Beer-Sheva, Israel Objective: This study was conducted to determine whether idiopatic oligohydramnios is associated with altered fetal renal artery blood flow velocimetry. Methods: A prospective study was designed. Thirty six (36) pregnant women with oligohydramnios (study group) were included. The control group was composed of 28 women with normal amniotic fluid index (AFI). All patients had intact membranes at 24–40 weeks gestation. Fetuses with congenital anomalies and small for gestational age fetuses were excluded. Oligohydramnios was defined as AFI of less than the 5th percentile for gestational age (Moore, 1997). Velocity waveforms of the renal artery were recorded and pulsatility index (PI) values were calculated. PI of more than the 95th percentile for gestational age was considered abnormal. Perinatal outcome was compared between the groups, including mode of delivery, Apgar scores, abnormal fetal heart rate monitoring patterns and perinatal death. Statistical analysis was performed using SPSS package. Results: The mean PI renal artery was not significantly different between the study and control group (2.09 + 0.43 vs. 2.04 + 0.77; respectively, p = 0.73). There was no significant correlation between AFI and renal artery PI in both study and control group (r =−0.024, p = 0.86) respectively. There was a significantly higher rate of at least one adverse pregnancy outcome in the group with oligohydramnios compared to the control group (63% versus 21%, p = 0.01). However, no significant difference in renal artery PI was demonstrated between patients with and without adverse pregnancy outcome (2.09 + 0.91 vs. 1.96 + 0.54; respectively, p = 0.64). Conclusions: Idiopathic oligohydramnios is not associated with changes in renal artery blood flow velocimetry in both normal and pregnancies with adverse outcome. P10.13 A cross-sectional study of fetal and uterine biometric indices in the first trimester of term pregnancies N. Potdar 1 , M. Khare 2 , S. C. Bell 1 , J. C. Konje 2 1 University of Leicester, UK, 2 Leicester Royal Infirmary, UK Objective: To determine the changes in fetal (yolk sac, fetal heart rate [FHR]) and uterine wall biometric indices during the first trimester of pregnancy. Methods: A cross-sectional study of 146 pregnant subjects evaluated by weekly transabdominal ultrasound scan between 6–12 weeks of gestation. The fetal biometric indices of crown-rump length, gestation sac, FHR, yolk sac (internal and external diameter, wall thickness) and the uterine decidua thickness from 2 defined sites were measured at each gestation in pregnancies that ended at term (37 weeks and more). The decidua was measured at the site of implantation and the opposite site in the same plane. A SPSS version 11.0 for Windows was used for statistical comparison in differences at each gestation. The mean ± SD of the various indices at each gestation were determined and a normogram constructed. Results: Two hundred and eighteen patients were studied but only 146 were included in the analysis as the rest either miscarried (n = 43), pregnancy ongoing (n = 12) or were lost to follow up (n = 17). The mean ± SD internal yolk sac diameter increased from 2.83 to 4.24 mm and the external diameter from 3.91 to 5.52 mm. The change in diameter from 6 – 12 weeks was statistically significant (P = <0.05). The mean ± SD thickness of the decidua on the implantation site increased significantly from 4.7 mm at 6 weeks to 16.09 mm at 12 weeks (P = <0.05). On the contralateral site there was a non-significant increase from 3.56 to 4.28 mm (P => 0.05). The mean ± SD fetal heart rate increased from 114 at 6 weeks to 160 at 12 weeks’ gestation. Conclusion: Measurement of fetal and uterine biometric indices in early pregnancy demonstrate constant changes in normal pregnancy. Deviation from these indices may predict abnormal pregnancy outcome. P10.14 The Singapore General Hospital charts of fetal size: head circumference, abdominal circumference and femur length H. K. Tan , S. Fook-Chong, S. L. Lee Singapore General Hospital, Singapore Introduction: Measurements of fetal size are used in assessing fetal growth, well-being and in the detection of fetal abnormalities. Many investigators have constructed charts of fetal size which are widely used in obstetric ultrasound examinations. Most of these adopted charts were from the Caucasoid population. Our department had constructed nomograms of head circumference (HC), abdominal circumference (AC) and femur length (FL) for 18–40 weeks gestation. It has been used by large ultrasound departments in Singapore for several years. We now have data from 12–40 weeks gestation which are from higher range machines and experienced operators. We have therefore, constructed new charts of HC, AC and FL from 12–40 weeks gestation. Design: A retrospective cross-sectional study. Methods: 36 000 women whose ultrasound and menstrual dates agreed within 10 days had their fetuses scanned in the routine antenatal clinic. The ultrasound technologists who performed the scans were all experienced operators using high resolution ultrasound scanners. All measurements were performed to standard protocols. Statistical analyses were performed using polynomial regression models and the methodology described by Altman (1994). Equations, means and 95th reference intervals were derived and reported for HC, AC and FL. Population-specific regression equations for HC, AC and FL have been proposed for Singaporean pregnancies. 442 Ultrasound in Obstetrics & Gynecology 2005; 26: 376–471