Objectives: To describe the feasibility and perinatal outcomes of fetal microneurosurgery for intrauterine myelomeningocele repair assisted by a high-definition exoscope system. Methods: A prospective cohort of consecutive fetuses with isolated open spina bifida referred to our fetal surgery centre in Querétaro, Mexico, during a three-year period (2016-2019). Fetal intrauterine myelomeningocele (MMC) repair was performed through a 1.5cm hysterotomy with the assistance of a high-definition three-dimensional exoscope system. Results: A cohort of 47 consecutive cases underwent fetal microneurosurgery for intrauterine MMC repair. A complete three-layer correction was feasible in all cases at a median gestational age (GA) of 25.3 (22.9-27.6) weeks and a median surgical time of 110 (64-200) min. Preterm rupture of the membranes was observed in eight cases (19.0%) at a median GA of 31.4 (26.0-35.1) weeks. The median GA at delivery was 35.1 (range, 26.0-39.6) weeks. During infant follow-up, 8 cases (19.0%) developed hydrocephaly requiring ventriculoperitoneal shunt placement or neuroendoscopy. All patients showed intact hysterotomy site at delivery. There were no maternal or fetal deaths but two neonatal deaths (4.8%) were reported due to complications related to preterm delivery. Conclusions: Intrauterine MMC repair by exoscopic-assisted microneurosurgery is feasible and is associated with good perinatal outcomes.

Virtual poster abstracts closed spinal dysraphism (CSD) intracranial signs are absent as the skin overlying the defect is intact. CSD is a spectrum of disorders ranging from isolated vertebral bony defects to complex dysraphic states. The objective of the study is to assess the feasibility of detecting CSD at the 11-14 week scan. Methods: Evaluation of fetal spine was done in two planes-the sagittal plane and the coronal plane in 9,363 cases. The skin integrity and spinal curvature was assessed in sagittal plane and the evaluation of vertebral bodies and posterior elements along with the ribs was done in the coronal plane. A follow-up scan after 2 weeks was done in suspicious cases. Results: 26 cases were detected with CSD of which 13 had hemivertebra in which 2 had a VACTERL association, 2 with diastometamyelia, 2 with complete sacral agenesis, 2 had severe shortening of spine with segmental spinal dysgenesis, 1 with neurenteric cyst, 1 with meningocele, 2 with spondylocostal dysostosis and 2 with kyphotic deformity of spine. Alteration in spinal curvature was seen in 40% of cases, 7% of cases showed abrupt ending of fetal spine with abnormal posturing of lower limbs, 60% of cases showed abnormal vertebral body alignment, 16% showed atypical ossification of fetal spine and rib abnormalities and 3% showed a lumbosacral swelling. 1 case of diastometamyelia, 7 cases of hemivertebrae and 3 cases of sacral spine abnormality with tethered cord were picked up in the subsequent anomaly scan and were missed at first trimester scan. Conclusions: Direct visualisation of fetal spine in the sagittal and coronal view helps in diagnosis of CSD. The coronal view of fetal spine with ribs gives additional information and the detection rate is higher at 14 weeks of gestation rather than at 12 weeks in first trimester. VP28.02 Cortical surface matching of the fetal cortex pre-and post-fetal surgery for open spina bifida