17th World Congress on Ultrasound in Obstetrics and Gynecology Poster abstracts phenomenon). We present the case of an AVM of the right fronto- parietal lobes, diagnosed 3 weeks after cardiomegaly was detected. A 38-year-old woman was referred for detailed sonography at 25 weeks, after fetal cardiomegaly was suspected on routine sonography at 22 weeks. Cardiomegaly was confirmed, with features of high-output heart failure. Mild cerebral ventriculomegaly was also detected; multiple intracranial echogenic spots and an echogenic rim above the body of the lateral ventricle were observed. Fetal anatomy and growth were otherwise unremarkable. Both CD imaging and magnetic resonance showed an irregular vascular anomaly in the right basal fronto-parietal area, measuring approximately 3 × 4 cm, with arterial pattern at pulsed Doppler. Magnetic resonance confirmed a periventricular hemorrhage. Both cardiac failure and cerebral damage suggested a dismal prognosis. Fetal hydrops developed and fetal death occurred at 31 weeks. A round-shaped anechoic lesion, with flow at CD, was only observed on gray-scale sonography at 28 weeks. Only a few cases of AVMs other than VGAM have been reported. Color flow imaging is diagnostic in these anomalies; however, in the present case no lesion to be studied with CD was initially depicted. Even if heart failure often develops late in the third trimester or in the postnatal life, in one reported case cardiomegaly was observed before VGAM was diagnosed, as in the present case of AVM. Brain hypoxic/hemorrhagic lesions are known complication of AVMs, but they represent late findings in the progression of the disease; on the contrary, in the present case these lesions could be depicted before the AVM was diagnosed. P38.05 Prenatally diagnosed fetal brain tumor R. Gerychova , E. Racanska University Hospital Brno, Czech Republic Congenital fetal brain tumors are very rare. Prenatal manifesta- tion is uncommon with high mortality rate. Etiology-environmental, genetic impact, infection in pregnancy, fetal anomalies, gender, multiple pregnancy. Neonatal manifestation includes a variety of symptoms. Focal symptoms are unspecific. The most frequently diagnosed tumors are teratomas, astrocytomas, Primitive Neuroec- todermal Tumors (PNET). We present a case report of an 18-year-old primigravida with a cancer positive family history. Uncomplicated pregnancy with negative first and second trimester ultrasound scan. Bilateral ventriculomegaly was diagnosed at 30 weeks of gestation. Detailed ultrasound scan showed female fetus with enlarged head circumference, obstructive hydrocephalus with bilateral ventricu- lomegaly up to 27 mm and anisoechogenic structure 70 mm in diameter filling the left lateral ventricle. Differential diagnosis of the fetal brain tumor was made. MRI confirmed the ultrasound finding and specified the supratentorial location of the lesion and described focuses of hemorrhage and calcification. The case was consulted with a maternal fetal specialist, obstetrician, neonatologist, oncol- ogist and radiotherapist with results- expansive fetal brain tumor of unknown origin (plexus choroid papiloma, carcinoma, PNET, astrocytoma, teratoma) causing serious obstructive hydrocephalus. Radio- or chemotherapy was not indicated, surgical therapy was impossible due to the size and location of the lesion. The only option was palliative care with histological tumor verification and hydro- cephalus drainage. Patient consented to the induction of premature labour followed by palliative care of the baby. Female fetus 2400 g, 46 cm was born at 33 weeks vaginally with Apgar score 1/1/0 and died 10 minutes after delivery. Autopsy confirmed immature benign teratoma. In case of brain mass finding it is neccessary to per- form detailed examination (ultrasound, MRI) followed by specialist consultation with respect to the parents wishes. P38.06 Prenatal diagnosis of Chiari III malformation: do not confuse with anencephaly J. K. Davies , M. Auckland, B. Carlson, B. C. Staat, M. Manco-Johnson, J. C. Hobbins University of Colorado Health Sciences Center, United States The Chiari malformations, first described in 1891, involve hindbrain anomalies of the spine and posterior fossa with hydrocephalus. They are often associated with other anomalies. Types I and II are the most common and are associated with meningomyelocele. Type III is rare, characterized by high cervical and occipital encephalocele with small posterior fossa, inferior cerebellar displacement and hydrocephalus. Few cases have been reported; little is known about the embryology, natural history and postnatal course with this type of malformation. We describe a prenatally diagnosed case of Chiari III malformation initially suspicious for anencephaly. Both 2D and 3D ultrasound was used to confirm diagnosis. Case: A 21-year-old female gravida 1 para 0 Haitian immigrant presented for a routine dating ultrasound at 19 weeks of gestation. Her pregnancy to this point had been uncomplicated. She declined quad screen testing. Imaging was suspicious for anencephaly secondary to perceived absence of calvarium above the orbits. No extracranial abnormalities were seen. She was referred for high risk ultrasound. At 21 weeks, there was the typical facial appearance of an anencephalic fetus where craniofacial structures are absent above the orbital ridges. However, fetal calvarium was found although no normal frontal cortex was visualized. Only a small midline falx was seen. A large occipitocervical encephalocele was characterized with 2D/3D ultrasound. No overlying meninges were seen. Splaying of the cervical vertebral elements consistent with rachischisis involved the entire cervical spine into the upper thoracic spine. There was a normal axis of the cranium to cervicothoracic spine without evidence of iniencephaly. The patient was counseled regarding the dismal postnatal prognosis for the fetus. She was not interested in amniocentesis or in pregnancy termination. Extensive antenatal 3D ultrasound with Chiari III malformation has not been previously described. P38.07 Importance of sulcation evaluation in a case of unilateral ventriculomegaly at 21 weeks’ gestation C. Celentano 1 , A. Iannicco 1 , T. Cardellini 1 , F. Presti 2 , K. Melchiorre 1 , M. Liberati 1 1 Department of Obstetrics and Gynecology, University of Chieti, Italy, 2 Department of Obstetrics and Gynecology, Azienda Ospedaliera di Verona, Italy Ventriculomegaly is the most frequent fetal brain anomaly with a prevalence of 1–22 per 1000 births. Outcome is usually related to associated anomalies and/or chromosomal anomalies. Unilateral ventriculomegaly is usually an isolated finding, and when isolated has little measurable effects on developmental outcome. Delayed appearance of ultrasonographic landmarks suggesting malformation of cortical development such as immature sulcation were found not specific in predicting polymicrogyria, heterotopia, and pachygyria/lissencephaly, particularly during second trimester of pregnancy. Unilateral location in early mid-trimester are usually associated to other brain and extra-CNS anomalies. We present a case of unilateral ventriculomegaly at 20 weeks’ gestation in a III-gravida II-para 22-year-old patient with family history of mental delay. The patient was sent to our MFM unit after the first ultrasound scan that depicted unilateral ventriculomegaly (10.4 mm). The fetus presented also omolateral absence of parieto-occipital fissure. Fetal growth was consistent with gestational age, and no further anomalies were described during second level ultrasound scan. At 23 weeks the 594 Ultrasound in Obstetrics & Gynecology 2007; 30: 547–653