Research Article Fetal Diagn Ther 2021;48:163–173 Open Fetal Microneurosurgery for Intrauterine Spina Bifida Repair Rogelio Cruz-Martínez a, b, c Felipe Chavelas-Ochoa d Miguel Martínez-Rodríguez a, c Karla Aguilar-Vidales e Alma Gámez-Varela a Jonahtan Luna-García a Hugo López-Briones a Joel Chávez-Vega e Ángel Augusto Pérez-Calatayud f Manuel Alejandro Díaz-Carrillo f Edgar Ahumada-Angulo a Andrea Castelo-Vargas a Eréndira Chávez-González a Israel Juárez-Martínez a Rosa Villalobos-Gómez a Carlos Rebolledo-Fernández g a Prenatal Diagnosis and Fetal Surgery Center, Fetal Medicine Mexico and the Fetal Medicine Foundation of Mexico, Queretaro, Mexico; b Instituto de Ciencias de la Salud (ICSa) , Universidad Autónoma del Estado de Hidalgo (UAEH), Hidalgo, Mexico; c Department of Fetal Surgery, Hospital de Especialidades del Niño y la Mujer Dr. Felipe Núñez Lara, Queretaro, Mexico; d Department of Pediatric Neurosurgery, Hospital de Especialidades del Niño y la Mujer Dr. Felipe Núñez Lara, Queretaro, Mexico; e Department of Anesthesiology, Hospital de Especialidades del Niño y la Mujer Dr. Felipe Núñez Lara, Queretaro, Mexico; f Department of Maternal Intensive Care, Hospital de Especialidades del Niño y la Mujer Dr. Felipe Núñez Lara, Queretaro, Mexico; g Department of Maternal Fetal Medicine, Hospital de Especialidades del Niño y la Mujer Dr. Felipe Núñez Lara, Queretaro, Mexico Received: April 16, 2020 Accepted: November 23, 2020 Published online: February 12, 2021 Rogelio Cruz-Martínez Fetal Medicine and Surgery Research Unit, Children and Women’ Specialty Hospital of Queretaro Unidad de Investigación en Neurodesarrollo, Instituto de Neurobiología UNAM-Juriquilla, Blvd Bernardo Quintana 4060, Querétaro 76125 (Mexico) rcruz @medicinafetalmexico.com © 2021 S. Karger AG, Basel karger@karger.com www.karger.com/fdt DOI: 10.1159/000513311 Keywords Fetal surgery · Microneurosurgery · Minihysterotomy · Myelomeningocele · Spina bifida Abstract Objectives: The aim of the study was to describe the feasibil- ity of open fetal microneurosurgery for intrauterine spina bi- fida (SB) repair and to compare perinatal outcomes with cas- es managed using the classic open fetal surgery technique. Methods: In this study, we selected a cohort of consecutive fetuses with isolated open SB referred to our fetal surgery center in Queretaro, Mexico, during a 3.5-year period (2016– 2020). SB repair was performed by either classic open sur- gery (6- to 8-cm hysterotomy with leakage of amniotic fluid, which was replaced before uterine closure) or open micro- neurosurgery, which is a novel technique characterized by a 15- to 20-mm hysterotomy diameter, reduced fetal manipu- lation by fixing the fetal back, and maintenance of normal amniotic fluid and uterine volume during the whole surgery. Perinatal outcomes of cases operated with the classic open fetal surgery technique and open microneurosurgery were compared. Results: Intrauterine SB repair with a complete 3-layer correction was successfully performed in 60 cases ei- ther by classic open fetal surgery (n = 13) or open microneu- rosurgery (n = 47). No significant differences were observed in gestational age (GA) at fetal intervention (25.4 vs. 25.1 weeks, p = 0.38) or surgical times (107 vs. 120 min, p = 0.15) between both groups. The group with open microneurosur- gery showed a significantly lower rate of oligohydramnios (0 vs. 15.4%, p = 0.01), preterm rupture of the membranes (19.0 vs. 53.8%, p = 0.01), higher GA at birth (35.1 vs. 32.7 weeks, p = 0.03), lower rate of preterm delivery <34 weeks (21.4 vs. 61.5%, p = 0.01), and lower rate of perinatal death (4.8 vs. 23.1%, p = 0.04) than the group with classic open surgery. During infant follow-up, the rate of hydrocephalus requiring ventriculoperitoneal shunting was similar between both groups (7.5 vs. 20%, p = 0.24). All patients showed an intact