Effects of in-utero open spina bifida repair using a laparotomy-assisted fetoscopic approach on the fetal cardiovascular system

Introduction Various treatment options for prenatal open spina bifida (OSB) repair have evolved over the past decades, including the laparotomy-assisted fetoscopic repair. However, little is known about fetal vascular regulation during laparotomy-assisted fetoscopic repair. Therefore, we aimed to describe cardiovascular effects during intervention in our cohort. Methods A total of 26 fetuses underwent laparotomy-assisted fetoscopic repair at a single-center between July 2021 and July 2024 and were prospectively included in this study. The intervention was performed using three-port, three-layer fetoscopic repair of OSB via a laparotomy-assisted approach. Fetal heart rate (FHR) and Pulsed Wave (PW) Doppler flow measurement of Pulsatility Index (PI) in the umbilical artery (UA) and middle cerebral artery (MCA) were recorded at thirteen defined time points throughout surgery. Occurrence of absent- or reversed UA flow (ARED) was documented. The MCA waveform was assessed for signs of fetal vasoconstriction (M-sign). Results Mean gestational age at surgery was 25 weeks. A significant increase in the PI in the UA before (PI 1.22±0.24) and after laparotomy (PI 1.75±0.37) was observed (p<0.001). ARED was recorded in 13.3% of cases after maternal general anesthesia, but not before and latest on first day after surgery. MCA PI decreased non-significantly during intervention. Before surgery a M-sign was present in six fetuses, during surgery it was seen only in one fetus. There were no significant changes in the FHR during surgery except for a drop after gas insufflation (FHR 129±5; FHR 125±7.0, p<0.001) compared to the FHR before surgery. During the postoperative course, the FHR increased significantly (day 0 141±10; day 4 143±9.8 p= 0.003). Conclusion Our study shows changes in UA PI and occurrence of ARED during laparotomy-assisted fetoscopic repair. FHR remained stable during surgery. Furthermore, the findings confirm the transient nature of these changes. The occurrence of Doppler and waveform abnormalities were related to maternal-fetal anesthesia and the procedure itself.