20th World Congress on Ultrasound in Obstetrics and Gynecology Poster abstracts of 21 chest size. The Bland-Altman analysis was used to compare the measurement agreement and bias for a single observer. Results: One hundred and twenty seven examinations were per- fomed. The chest size ranged from 15.0 to 17.3 cm with mean of 16.6 cm (±0.7 cm, SD) on the 24 th week to 21.5 to 24.8 cm with mean of 23.1 cm (±0.8 cm) on the 32 nd week. The intra-observer variability study utilizing the intraclass correlation coefficient was of 0.919. Conclusions: The fetal chest measurement by multiplanar method of 3-dimensional shows good reproducibility and can be utilized to quantify the thoracic circumference. P08.18 Relationship between lung area to chest size ratio in normal fetuses by three-dimensional ultrasound using the multiplanar method I. S. Britto 1 , G. D. Tedesco 1 , S. S. Herbst 1 , L. C. Bussamra 1,2 , F. M. Andrade 1 , E. Araujo Junior 2 , T. Aoki 1 , C. L. Drummond 1 1 Gynecology and Obstetrics Department, Medical Science College of Santa Casa of S ˜ ao Paulo (FCMSCSP), Sao Paulo, Brazil; 2 Gynecology and Obstetrics Department, S ˜ ao Paulo Federal University, Sao Paulo, Brazil Objectives: To evaluate the relation between lung area to chest size ratio using the 3D multiplanar method between 24 and 32 weeks of gestation. For chest size measurements obtained by 3D multiplanar method, the reference was specifically placed in the descending aorta and moved upward until the level of the inferior scapular angle. The left and right lung areas were measured on the same cross-sectional plane of the thorax, by manual tracing of the limitis of the lungs. Methods: A longitudinal prospective study was conducted with 56 uncomplicated pregnancies between 24 and 32 weeks of gestation. The Pearson correlation was calculated to evaluate the relationship between lung area (left and right) to chest size ratio. Reference intervals were estimated per week of gestation in the proposed interval. Percentiles 5, 10, 25, 50, 75 and 90 were calculated for each gestational age between 24 to 32 weeks. Results: One hundred and twenty seven examinations were perfomed. A strong correlation between lung area (left and right) to chest size ratio was observed (Pearson correlation = 0.761). The lung area to chest size ratio ranged from 0.56 to 0.70 with mean of 0.64 (±0.03 SD) on the 24 th week to 0.79 to 1.35 with mean of 0.92 (±0.13 SD) on the 32 nd week. Conclusions: The relationship between lung area to chest size ratio by the 3-dimensional ultrasonography using the multiplanar method using the descending aorta and the inferior scapular angle as reference can be utilized to evaluate fetal lung growth. P09: UNUSUAL SYNDROMES P09.01 Prenatal diagnosis of a familial Saethre-Chotzen syndrome J. Gebb , K. Demasio, P. Dar Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY, USA Saethre-Chotzen syndrome (SCS, Acrocephalosyndactyly Type III, MIM 101400) is an autosomal dominant hereditary disorder char- acterized by craniofacial and limb anomalies and is one of the major craniosynostoses. We report on a 39 year-old para 2 who reported a personal history of SCS and two offspring afflicted with the syn- drome. Her pregnancy was complicated by morbid obesity, chronic hypertension and thrombophilia as well as a surgical history of two cesarean deliveries, a laparoscopic gastric banding procedure and a laparoscopic cholecystectomy. At 19 weeks gestation, a detailed anatomical survey revealed an irregularly shaped fetal skull in a transverse view (Fig 1) and narrow antero-posterior dimension in a sagittal view suggestive of coronal suture synostoses. Additional findings were clinodactyly of the right hand and a broad great toe on the left foot. The patient was informed that the findings were sug- gestive of the fetus also having Saethre-Chotzen syndrome. She was offered genetic and pediatric cranio-facial surgery consultation but declined. At 39 weeks the patient delivered via repeat cesarean sec- tion a 2721 gr female infant with Apgars of 9 and 9. Postnatal genetic assessment confirmed the diagnosis of Saethre-Chotzen Syndrome. In conclusion, we report on the first prenatal sonographic diagnosis of SCS. Midtrimester prenatal diagnosis will allow adequate time for genetic and pediatric counseling for affected families. Supporting information can be found in the online version of this abstract. Cranial asymmetry on transverse view of the cranium at 19w4 gestational age. P09.02 Tetrasomy 9p with septated cystic hygroma, nonossified nasal bone, prominent midface, Dandy Walker malformation, cardiac and limb anomalies U. Kim, H. Casele, V. A. Catanzarite Maternal Fetal Medicine, Childrens Specialists of San Diego, San Diego, CA, USA A 38-year-old, G6 P 4013 was referred at 16 weeks following the finding of a septated cystic hygroma with nuchal translucency 5.6 mm at 11 weeks. Mutiple abnormalities were present, includ- ing septated cystic hygroma, non-ossified nasal bone, micrognathia, Dandy-Walker malformation (DWM), hydrocephalus, pericardial effusion, suspected inlet VSD and pulmonic stenosis, and limb abnormalities including hyperextended left knee and right clubfoot. After genetic counseling, amniocentesis was performed; all colonies showed 47 chromosomes with an isodicentric chromosome 9 with the breakpoint on the long arm at band q21, with tetrasomy for the short arm of chromosome 9 and the region between the centromere and the band q21 on the long arm. Tetrasomy 9p is a very rare, with about 50 cases reported. Manifestations include mental retardation, growth restriction, CNS abnormalities including DWM and agenesis of the corpus callosum, hypertelorism, micrognathia, cleft lip/palate, and cardiac, limb, and renal abnormalities. Only a handful of cases have been diagnosed prenatally; findings have included strawberry shaped head, DWM, cleft lip, cardiac anomalies, hyperechoic kid- neys, arthrogryposis and, and clubfeet. This is the first reported case with prenatal sonography showing a cystic hygroma. Supporting information can be found in the online version of this abstract. Counterclockwise: Cystic hygroma, profile showing nonos- sifed nasal bone and micrognathia, hyperextended knee, clubfoot. P09.03 Prenatal diagnosis of trisomy 5p: a case report E. Kent 1 , J. Unterscheider 1 , A. Green 2 , F. Breathnach 1 1 Royal College of Surgeons in Ireland, Dublin, Ireland; 2 National Centre for Medical Genetics, Our Lady’s Hospital, Crumlin, Dublin, Ireland A 34 year old woman, with one prior uncomplicated pregnancy, reg- istered for antenatal care at 30 weeks’ gestation. Fetal sonographic evaluation detected unilateral cerebral ventriculomegaly (11 mm), bilateral talipes and polyhydramnios. An MRI documented mild dilatation of both lateral ventricles and confirmed the presence of 200 Ultrasound in Obstetrics & Gynecology 2010; 36 (Suppl. 1): 168–305