3–7 September 2006, London, UK Oral communication abstracts Results: Cerebral abnormalities developed prenatally in 27 fetuses (9.37%, 27/288). Prenatal diagnosis of these lesions was achieved primarily by US and MRI in 21/27 (78%) and in 6/27 (22%) fetuses respectively. Cerebral abnormalities developed following primary laser coagulation, serial amnioreduction or expectant management in 12/222 (5.40%), in 9/124 (13.63%) and in 3/14 (21.4%) fetuses respectively. Abnormalities developed after single intrauterine fetal death (IUD) in 14 cases including 6 severely anemic survivors as a result of exsanguination in their dead co-twin. These lesions developed following primary laser coagulation, amniodrainage and expectant management in 3/55 (5.45%), 7/20 (35%) and 1/14 (7%) cases respectively. Conclusions: Cerebral morbidity in TTTS mainly occurs following vascular disruptive lesions. Both donors and recipients are at risk of developing either ischemic or hemorrhagic lesions. The risk of developing cerebral lesions in single survivors is significantly less following laser treatment. Timing of the triggering event is critical for serial US and MRI follow-up examination. OC84 How early do imaging changes occur in MC/DA surviving twins following co-twin demise? E. A. Dunn 1 , R. Windrim 1 , F. Alkazaleh 1 , C. Pennell 1 , P. G. R. Seaward 1 , E. N. Kelly 1 , S. Blaser 2 , G. Ryan 1 1 Mount Sinai Hospital, Toronto, Canada, 2 Sick Kids’ Hospital, University Of Toronto, Canada Introduction: Intrauterine demise of a monochorionic (MC) co-twin places the survivor at high risk of intracranial damage due to acute hypotension, the risk being up to 95% if the recipient dies. It has been suggested that intracranial changes may not appear for 2–3 weeks in the survivor. Objectives: To assess the time interval between insult and devel- opment of detectable ischemic brain lesions on US and/or MRI in surviving twins and to discuss management options. Methods : Nine cases of documented MC co-twin demise, 4 of whom underwent cord occlusion were retrospectively analyzed; 7/9 were in cases of TTTS. Results: Cases were identified from 23 + 1–29 + 4 wks. In 5, imag- ing changes were detectable within 18 hours of co-twin demise. Elevation in the MCA PSV on Doppler US, suggestive of anemia, was present prior to the detection of brain lesions in most cases. In 2 cases, very severe brain lesions were noted in a recipient, and in a donor, 2 days after a normal scan – prompting cord occlusion. Both pregnancies delivered within a few days of the procedure (24, 29 wks). In the other 2 cases where a recipient’s cord was occluded because of acute intraoperative terminal bradycardia (at the time of planned laser for TTTS), there were no detectable brain lesions in the surviving donor twin (as would have been expected to occur in 95% of cases) and both children are normal at long term follow up. Conclusions: Changes in MCA Doppler PSV are useful in predicting and MRI is useful in confirming US findings of hypotensive brain damage. Lesions may be detectable on US and MRI within 24 hours of the co-twin’s demise. Immediate cord occlusion in pre-terminal cases may be protective. OC85 Accurate neurosonographic prediction of brain injury in the surviving fetus after the death of a monochorionic co-twin G. Simonazzi 1 , G. Pilu 1 , M. Segata 1 , F. Sandri 2 , G. Ancora 2 , G. Tani 3 , T. Ghi 4 , N. Rizzo 1 1 Medicina Et ` a Prenatale, University of Bologna, Italy, 2 Department of Neonatology, University of Bologna, Italy, 3 Department of Pediatric Radiology, University of Bologna, Italy, 4 Department of Obstetrics and Gynecology, University of Bologna, Italy Objective: To assess the feasibility of the prenatal diagnosis of brain injuries in the surviving fetus after demise of a monochorionic co-twin. Methods: A retrospective observational study of monochorionic twin pregnancies with single death referred to a tertiary care center in the period 1990 – 2004. Whenever possible, the intracranial anatomy of the surviving twin was evaluated in detail by multiplanar neurosonography preferably with a transvaginal probe. Results: Twelve pregnancies ranging in gestational age from 20 to 32 weeks were seen, most frequently in association with twin transfusion. In one case the surviving twin died in utero. Brain injuries were present in 8/11 remaining cases. In 6/8 cases in which fetal neurosonography was performed abnormal findings were identified including intracranial hemorrages, brain atrophy, porencephaly and periventricular echogenicities evolving into polymicrogyria. Prenatal diagnosis of brain lesions was always confirmed and all affected infants who survived have severe neurologic sequelae. Two fetuses had normal cerebral structures both on the antenatal neurosonogram and on postnatal imaging and are following normal developmental milestones at one and five years. Fetal magnetic resonance was performed in two cases and confirmed the ultrasound diagnosis. Conclusions: Antenatal neurosonography is a valuable tool for the prediction of the neurologic outcome in fetuses surviving after the intrauterine death of a monochorionic co-twin. Although our experience is limited, extrapolation from postnatal series suggest that magnetic resonance should also be offered. OC86 Is there a role for intrauterine rescue transfusions in anemic monochorionic survivors? E. Q. Quarello , J. S. Stirneman, J. P. B. Bernard, F. L. Leleu, Y. Ville Centre Hospitalier Intercommunal de Poissy St Germain en Laye, France Objective: To evaluate the role of intrauterine transfusions (IUT) in anemic monochorionic (MC) survivors following intrauterine death of their co-twin. Design: Retrospective analysis. Setting: Experience of a single centre between 1999 and 2006 Population: 21 cases of anemic MC survivors that underwent intrauterine transfusions. Methods: Ultrasonographic features and Doppler measurements of pic-systolic velocity in the middle cerebral artery (MCA PSV) were used within 24 hours of the death of one MC twin in order to detect anemia in the survivor. Fetal blood sampling was performed when there was hydropic features or when MCA-PSV > 1.5 MoM. Following was by weekly ultrasound and fetal cerebral MRI was performed at 32 weeks. Results: Anemia was suspected and confirmed in 21 fetuses. Intrauterine death (IUD) was spontaneous in 4 cases, and fol- lowed amniodrainage, laser coagulation and cord coagulation in 6, 10 and 2 cases respectively. Median gestational age at the time of death was 24 (20 to 28 weeks) weeks. The exact time of death was unknown in 2 cases. Survivors were transfused 8 to 48 hours following their co-twin demise. Transfusion volumes ranged from 25 to 70 ml and resulted in 10 (47.6%) healthy survivors. 8 (28.6%) developed abnormal cerebral findings, 3 died in utero and 2 had neonatal death at 20 and 25 weeks. The outcome was not correlated with hemoglobin concentration or gestational age at transfusion. Conclusion: Intrauterine rescue transfusion may prevent fetal death but not neurological morbidity. This management could therefore offered in countries where late termination of pregnancy is legal. Ultrasound in Obstetrics & Gynecology 2006; 28: 359–411 383