Supporting the Achilles Heel of Fetal Surgery – Ultrasound-guided placement of Membranous-Defect- Coverage-Devices (MDCD) during minimally-invasive fetoscopic surgery for spina bifida is associated with prolonged gestation and a lower rate of chorioamnionitis

Background: Uncovered defects within the chorioamniotic membranes from insertion of 5-mm-trocars (external diameter) were associated with early preterm delivery and chorioamnionitis following fetoscopic surgery for spina bifida aperta (SBA). In addition, closure attempts with collagen plugs were in vain to cover defects larger than 10 mm around a trocar insertion site. Therefore, the purpose of this retrospective study was to analyze the efficacy of a mechanical Membranous-Defect-Coverage-Device (MDCD) for fetoscopic surgery in prolonging gestation and preventing complications.

Patients and methods: Retrospective analysis: 42 fetoscopic SBA surgeries that were completed by ultrasound-guided placement of an MDCD via each of three trocars at a mean gestational age of 23.7 weeks (Group I) were compared with 9 earlier cases operated without MDCD-placement at a mean gestational age of 24.5 weeks (Group II). Survival rate, intervall between surgery and delivery, gestational age at delivery, incidence of amniotic leakage, chorioamnionitis and oligohydramnios were compared between the two groups.

Results: All but one Group I-babies (97.6%) and all but one Group II-babies (89%) survived to discharge. In Group I, the mean interval between surgery and delivery was 64.5 days and the mean gestational age at delivery was 33.0 weeks. In Group II, the mean interval between surgery and delivery was 28.6 days, and the mean gestational age at delivery was 28.7 weeks. Amniotic fluid leakage occurred in 35 Group I-patients (83.3%) and all (100%) of Group II-patients. Two Group I-patients (4.6%) and six Group II-patients (66.6%) developed chorioamnionitis over the remainder of gestation. One fetus of either group died from prematurity related to either infection or preterm delivery.

Conclusion: Ultrasound-guided coverage of the three chorioamniotic membrane defects with MDCDs at trocar removal results in significantly later delivery and a lower incidence of chorioamnionitis after fetoscopic surgery for SBA compared to procedures undertaken without coverage.