Thorax diameter or defect diameter of giant omphaloceles is not predictive for fetal outcome. The perinatal care of these abdominal wall defects still remains a multidisciplinary challenge, but the outcome of giant omphaloceles is favorable at experienced centers.

grade should be assessed longitudinally as the change over time provides additional value for risk prediction. P28.08Thorax-to-head ratio and defect diameter-to-head ratio in giant omphaloceles as predictor for fetal outcome Objectives: To investigate the relationship between the thorax diameter and defect diameter of giant omphaloceles as a predictor for fetal outcome. Methods: In a retrospective study, 17 fetuses with isolated giant omphaloceles were included for evaluation. The anterior-posterior thorax diameter and the defect diameter were measured from ultrasound images. For analysis, the thorax-to-head ratio (T/HC), the defect diameter-to-head ratio (DD/HC), and the quotient of the defect diameter and the thorax diameter (DD/T) were calculated. The days of ventilation (t ventilation ), the duration until hospital discharge (t hospital ), and the type of treatment were recorded as outcome parameters. Results: No relationship was found between the calculated ratios (T/HC, DD/HC, or DD/T) and neither t hospital (r = -0.418, p = 0.095; r = -0.153, p = 0.556; and r = -0.023, p = 0.929; respectively) nor t ventilation (r = -0.391, p = 0.121; r = 0.041, p = 0.875; and r = 0.121, p = 0.645, respectively). The type of postnatal treatment was not associated with the three calculated ratios or t hospital (r = 0.155, p = 0.553; r = 0.019, p = 0.942; and r = 0.012, p = 0.965; r = -0.009, p = 0.973, respectively). In 53% of cases, t hospital was delayed due to additional and independent postnatal complications. Conclusions: Thorax diameter or defect diameter of giant omphaloceles is not predictive for fetal outcome. The perinatal care of these abdominal wall defects still remains a multidisciplinary challenge, but the outcome of giant omphaloceles is favourable at experienced centres. P29: IMPROVING OUR MANAGEMENT OF TWIN PREGNANCIES P29.01Maternal hemodynamic changes and complications following intrauterine interventions for monochorionic twin pregnancies P. Greimel, A. Zenz, B. Csapo, P. Klaritsch Department of Obstetrics and Gynecology, Medical University of Graz, Graz, AustriaObjectives: Twin-twin transfusion syndrome (TTTS) is a challenging complication in monochorionic twin pregnancies. TTTS is caused by placental anastomoses, facilitating unbalanced flow between the two fetuses resulting in compromised circulation of one twin while the other one suffers from volume overload. This leads to stepwise deterioration and finally to death of one or both fetuses if untreated.State-of-the-art treatment for TTTS is intrauterine laser coagulation of connecting placental anastomoses. At the end of this procedure, drainage of amniotic fluid is routinely performed. Following high-volume drainage of amniotic fluid, maternal hemodynamic effects such as hypovolemia, oliguria and hemodilution can be observed.We aimed to report on maternal hemodynamic changes and complications after intrauterine interventions for TTTS. Methods: We conducted a retrospective single centre analysis in 80 cases of TTTS treated with intrauterine laser c...