7–11 October 2007, Florence, Italy Poster abstracts feet and at this moment the hypothesis of congenital arthrogryposis was placed. At 18 weeks the scan showed the fetus in the same position but with marked hypomobility and flexion of limbs. The hypothesis of fetal akinesia sequence was placed and after discussion, the couple decided for termination of pregnancy. Fetopathological examination showed a 200 g male fetus, with nuchal and neck edema, flexion contractures of limbs, marked scoliosis of all vertebral column extension, rocker-bottom feet and multiple pterygia of great joints, leading to diagnosis of lethal multiple pterygium. This case report demonstrates the importance of the first trimester scan in the diagnosis of early fetal syndromes. P50.13 Cephalothoracopagus janiceps disymmetricus with gastroschisis, a very rare form of conjoined twins: a case report G. Oner 1 , A. Tayyar 1 , G. Acmaz 1 , B. Acmaz 2 , M. Tayyar 1 1 Erciyes University Faculty of Medicine, Turkey, 2 The Kayseri State Hospital, Turkey In 1: 50000 to 1: 100000 births, conjoined twins occur, caused by incomplete division of the embryonic disc more than 13 days after fertilization. Due to improvement in ultrasound imaging it is now possible to diagnose conjoined twins as early as the first trimester. Cephalothoracopagus janiceps disymmetricus with gastroschisis is the rarest type of conjoined twins. This type has two faces, on the opposite sides of the head, with one face usually being rudimentary. Other findings include separation of the lower abdomen and pelvis resulting in four arms and four legs. A 20-year-old nulliparous woman was referred to our department at 13 weeks of gestation. Two dimensional ultrasound examinations showed that this fetus was conjoined twins with fusion of the head and chest. After counseling, a vaginal delivery of conjoined twins was achieved by induction with prostaglandin. Placental examination confirmed monochorionicity, with single insertion of umbilical cord which contained two arteries and one vein. The fetuses, 8.5 cm in length, had a large conjoined head with two faces, one located on each of the opposite sides of the head; fused from head disymmetrically and also fused from chest. Four arms and four legs are present. One fetus had gastroschisis that was a herniation of abdominal contents through the body wall directly into the amniotic cavity. Autopsy revealed one heart with hypoplastic ventricles and one circulatory system, two immature respiratory organs. The other organs of twins were separated. The separate genitourinary tracts appeared male. In this case, two dimensional ultrasonography demonstrated that the facial, truncal and abdominal features are characteristic of cephalothoracopagus twins. The pregnancy was terminated because there was apparently no hope for surgical separation due to the extensive fusion of vital organs. P50.14 Massive omphalocele: management and outcome: a case report L. Rosignoli 1 , G. Centini 1 , A. Kenanidis 1 , M. Messina 2 1 Prenatal Diagnosis Unit, Department of Obstetrics and Gynecology, University of Siena, Italy, 2 Pediatric Surgery, University of Siena, Italy The repair and survival rate of a fetus with a giant omphalocele, > 5 cm in diameter, is about 10%; representing a technically difficult surgery. Also with the presence of other anomalies such as intestinal, cardiac and renal, and with a poor outlook of successful results, requires much parental counseling. Respiratory failure at birth in infants with an omphalocele, is a significant predictor of mortality. A 32-year-old woman diagnosed with an omphalocele 3.7 cm in diameter in her 11th week decided to do a chorionic villus sampling after a preliminary exam by a fetal anatomy study. The karyotype was 46XX; the incidence of aneuploidy is lower in fetuses with giant omphaloceles in respect to fetuses with smaller ones. There was a serial echographic scan to exclude high complications and to evaluate the hepatic and bowel damage. The sonograph recognized the vessel’s anatomy in the abdominal cavity by the progressive external compression of the herniated organs; the presence of the liver in the herniated sac was evident from the first exams. The fetus showed adequate growth; the omphalocele diameter during pregnancy was 3.7–4.8–5.3, nearly 7 cm before the surgery. The baby was born 2.560 grams at 37 weeks +3 days after a prevention of distress syndrome by Cesarean section. The Apgar Index was 8 at 1–5 min., and no ventilatory support was required. The surgical technique used was ‘stretching’ the abdominal wall to put the liver back in the abdominal cavity with a delicate maneuver and then a primary closure. One week after surgery the baby was taken out of the Intensive Unit Care, and one month after delivery, was taken home. The parents consciously chose and relied on medical technology and equipment. The management of omphalocele is due to the presence of other anomalies, in this case the giant exomphalos being successfully managed using multiple support with the appropriate antenatal counseling, serial scan, but specifically by courageous surgery technique. P50.15 First trimester diagnosis of sirenomelia by real-time three-dimensional ultrasound: a case report C. Batukan, M. T. Ozgun, M. Basbug , G. Oner, H. Akgun Erciyes University, Faculty of Medicine, Turkey Sirenomelia, characterized by complete fusion of the lower limbs in combination with severe urogenital and gastrointestinal malformations, is a rare and usually lethal disorder. Although two-dimensional (2D) conventional ultrasound is instrumental in diagnosing sirenomelia, this report provides for the first time three- dimensional (3D) ultrasound images of sirenomelia diagnosed in the first trimester. A 22-year-old woman, gravida 3, para 1, was referred for a targeted ultrasound examination to our ultrasound unit in the 11th week of gestation because an intraabdominal cyst was detected during a routine scan. B-mode transabdominal and transvaginal ultrasound examinations showed a left-sided intraabdominal cystic structure measuring 9.6 × 9.4 mm in diameter, which was located just beneath the stomach. Meticulous scanning revealed fusion of the lower limbs, a unique pelvic bone and a single umbilical artery. The sacrum, both kidneys and bladder were not visible. These sonographic findings favored the diagnosis of sirenomelia. Presence of lower extremity fusion was further supported by transabdominal 3D ultrasound imaging. After non-directive counseling, pregnancy termination was requested by the couple. Postmortem radiological study confirmed the prenatal diagnosis, showing a single femur, absent sacrum, and hypoplastic pelvic bones. The cystic structure detected on prenatal ultrasound turned out to be dilatation of sigmoid colon during autopsy. And the gross appearance of the fetus confirmed the existence of a single lower extremity. The dissection found bladder agenesis and presence of female internal genitalia. Other intraabdominally located organs were unsuspicious. Placental examination revealed a single umbilical artery. Fetal karyotype was 46, XX. In conclusion, sirenomelia should be carefully sought when an intraabdominal cystic structure is detected on prenatal ultrasound. Subsequent 3D ultrasound scan may be valuable in confirmation of the diagnosis. Ultrasound in Obstetrics & Gynecology 2007; 30: 547–653 647