A. Araújo

Gasless Fetoscopy: A New Approach to Endoscopic Closure of a Lumbar Skin Defect in Fetal Sheep

Objective: To develop a new endoscopic approach to the correction of a myelomeningocele-like defect in fetal sheep. Methods: The fetuses of 9 pregnant ewes, with an average gestational age of 115 days, were subjected to a 3.0 × 2.0 cm removal of the skin over the lumbar spine, performed through hysterotomy. The uterus was closed, and three 5-mm endoscopic cannulas, without valve mechanisms, were inserted. In the pilot phase (2 animals), we initially worked exclusively in the amniotic fluid space. In the study phase, we partially withdrew the fetus from the amniotic fluid to completely expose its back. By simply allowing air to enter the amniotic cavity (without gas injection), a working space was created using a uterine lift device. The skin around the defect was dissected, and a biosynthetic cellulose material was applied to cover the area. A continuous suture of the skin was performed to completely hide the material. Results: The combined air/fluid space allowed the skin to be successfully closed in 6 out of 7 cases in the study phase. All fetuses were alive at the end of the procedures. Time to complete the endoscopic part of the procedure fell from 3 to 1 h by the end of this series. Premature birth occurred in 2 of the 4 cases allowed to continue with the pregnancy. Conclusion: A new gasless fetoscopic surgery technique was developed as an alternative to current techniques used for fetal endoscopic surgery.

Validation of the ovine fetus as an experimental model for the human myelomeningocele defect

PURPOSE To produce a myelomeningocele-like human defect in the ovine fetus and validate this experimental model in our population. METHODS A prospective study on 12 pregnant sheep of a crossed Hampshire/Down breed where a spinal defect was surgically created between Day 75 and Day 77 after conception. The technique consisted of a hysterotomy with exposure of fetal hind limbs and tail up to the mid spine. Fetal skin, paravertebral muscles, and 4 posterior spinal arches were excised, exposing the spinal cord. Duramater was opened and the medulla was incised until the medullar canal. Animals were euthanized at 139 days of gestation for fetal evaluation. The central nervous system was submitted to post-mortem magnetic resonance imaging (MRI) and the spine was submitted to pathological examination. RESULTS The defect was created in 13 fetuses and 5 survived. Mean gestational age at necropsy was 121.6 days (varying from 93 to 145 days). Macroscopically, the defect was present in 4 cases. Microscopy revealed a flattened medulla with disappearance of the medullar canal and disruption of normal medullar architecture with neuronal apoptosis and/or fusion of the piamater and duramater. The MRI showed herniation of the cerebellum into the cervical canal and syringomyelia. CONCLUSIONS The surgically produced defect mimics the defect found in the human fetus, including the Arnold-Chiari malformation. Post-mortem MRI was used for the first time in our study and proved an excellent alternative for demonstrating the cerebellar herniation. We standardized the technique for creating the defect in our population.

Simplified correction of a meningomyelocele-like defect in the ovine fetus

PURPOSE To develop a simplified technique for antenatal correction of a meningomyelocele -like defect in fetal sheep to allow direct skin closure. METHODS A spinal defect was surgically created at 75 days of gestation in the fetuses of 36 pregnant sheep, 23 survived the surgery. At 102 days gestation, the defect was corrected in 14 cases (9 were left untreated). Skin surrounding the defect was dissected below the dermis to permit its edges to be approximated and sutured, without interposing any material to its edges. An interface material intended to protect the neural tissue from skin adhesion was used and the skin defect was completely closed over it. Pregnancy was allowed to continue up to 138 days gestation, the fetuses were submitted to macroscopic and microscopic analysis. RESULTS The defect was successfully corrected in 90.9% in the experimental group, and spontaneous closure occurred in 22.3% in the control group (p < 0.05). The survival rate after the creation and correction of the defect was 63.4% and 78% respectively. CONCLUSION This simplified technique was successful in the correction a meningomyelocele-like defect, in the fetal sheep.

OC124: A different technique for the correction of a ‘myelomeningocele-like’ defect in ovine fetus

Objective: To evaluate the accuracy of three-dimensional ultrasonography in predicting the level of the defect in spine bifida. Patients and Methods: Between January 2005 and January 2006, the level of spine bifida was evaluated prenatally on three-dimensional ultrasonography (3DUS) using the rendered bone mode. All cases underwent postnatal surgery immediately after birth. Prenatal results obtained on 3DUS were compared to surgical level and to radiological level. Results: Up to now, 21 cases were completely evaluated. The correct surgical level was predicted in 9 (42.86%) cases; difference of one level was observed in 9 (42.86%) fetuses and difference of 2 levels in 3 (14.28%). Up to 1 and to 2 levels of agreement were observed in 18 (85.71%) and 21 (100%) cases. Using the postnatal radiological diagnosis, the correct level was predicted in 9 (42.86%) cases; difference of one level was observed in 9 (42.86%) fetuses and difference of 2 levels in 2 (14.29%). Up to 1 and to 2 levels of agreement were observed in 18 (85.71%) and 21 (100%) cases respectively. Conclusions: In our experience, 3DUS (rendered skeletal mode) is a good method to evaluate the level of spine bifida, with difference of two levels in 14.29% of cases when compared to postnatal surgical and radiological diagnosis.

OC125: New “suspension” endoscopic technique to correct fetal myelomeningocele: a pilot study in the ovine model

days 74 and 78 after conception. At 98 to 112 days an attempt to correct the defect was made in 11 cases and 6 fetuses remained uncorrected (control group). Using an open uterine approach the fetus was partially exposed from its tail to the lumbar spine. The skin around the defect was dissected below the dermis to permit the placement of an interface material over the exposed neural tissue and the skin. The skin was then completely closed over the defect using a separated suture. Pregnancy was allowed to continue and lambs were sacrificed between 137–145 days of gestation. The specimens were submitted to macroscopic and microscopic analysis. The correction was considered successful when more then 70% of the skin was closed. Results: The survival rate after the creation of the defect was 68% (17/25) and 90% (10/11) after correction. Macroscopically the skin was completely closed in 7 out of 10 cases in the corrected group and in 2 out of 6 cases in the control group. Neverthless 80% (8/10) were considered successful in the corrected cases. Transverse sections of fetal spine were microscopically analyzed in average 132 days of gestation (range 118–145 days) and the medulla had been reached in all fetuses in both groups. Conclusions: The new simplified technique was successful in the correction of the defect. We believe it can be more easily applied in an endoscopic approach for correction a human myelomeningocele.

OP06.21: Comparison of two interface materials for the in utero repair of fetal meningomielocele in the sheep model

color Doppler signal in approximately a third of the tumor. Signs of fetal heart failure and hydrops disappeared dramatically and fetal combined cardiac output was reduced (730 ml/mn). A second attempt was scheduled at 29 weeks. However due to premature rupture of membranes, Cesarean section was performed and a 1300 g premature baby with a 1300 g SCT was delivered. Surgical treatment was uneventful and at 1year of age the baby is doing well. Our preliminary experience suggests that in utero embolization with Histoacryl may be a useful tool to reduce cardiac output in large vascular sacrococcygeal teratoma. However, this new therapeutic approach needs to be correctly evaluated.

P09.20: Fetal therapeutic bronchoscopy in animal model: modified technique, applications and perspectives

pregnancies) and 5 have survived (38.5% survival rate). The medium gestational age at necropsy was 121.6 days (varying from 93 to 145 days). Macroscopically the defect was present in 4 cases. Microscopy revealed a ‘‘flat’’ medulla with no medullar canal and a fused dura and piamater. MRI showed caudal cerebellar tonsils herniation through the foramen magnum (hindbrain herniation) and syringomyelia. Conclusion: The produced defect hystologically mimics the defects in the human fetus, including the Arnold-Chiari malformation. The ovine fetus can be used as an animal model for the human meningomyelocele defect. We established a standard technique to produce such a lesion.

P09.19: Validation of the ovine fetus as an experimental model for the human myelomeningocele defect: preliminary results

discordant hemoglobin levels were managed with intrauterine transfusion only (8), re-laser (2) or cord coagulation (3). Fetal survival was of 43% and 73% in cases with recurrent TTTS and isolated discordant hemoglobin levels, respectively (p = 0.024). Conclusion: Incomplete coagulation and subsequent recurrent TTTS or isolated discordant hemoglobin levels occurred in 27% of double survivors. Serial ultrasound scan with MCA-PSV measurements proved invaluable in the follow-up of double survivors to detect isolated discordant hemoglobin levels at an early stage.