219: Feasibility and safety of three- and single-port fetoscopy for spina bifida in the fetal lamb

Abstract

New endoscopic prenatal spina bifida (SB) repair techniques are being proposed. These should be preclinically validated. Two-layer SB-repair has been shown feasible and effective in the fetal lamb model. Herein, we assessed the feasibility and safety of three- and single-port fetoscopic 2-layer SB repair modifications. We used a standardized skin-defect fetal lamb model (100 days; term 145 days). We first performed a 7.5cm- hysterotomy, inserted a microcatheter in the fetal carotid artery and under the skin nearby a 4x2cm lumbar skin marking and closed the uterus. Animals were randomly assigned to either three (0.8 and 2x0.3cm) or single (1.5cm) port uterine cannulation. We performed a 10-step simulated fetoscopic 2-layer closure of skin defect, fascial incision and mobilization, with coverage by a subcutaneous collagen patch and running skin closure under humidified warmed CO2 insufflation. Primary outcomes were persistent normal pH (pH=7.25±0.04) (safety) and postoperative watertightness of the skin closure in ≥70% of cases (feasibility). Secondary outcomes were fetal and maternal acid- base status, hemodynamics, fetal survival and operation times. Surgeons had a prior training for this procedure on a high-fidelity in vivo trainer. Twelve fetuses (one per ewe) were operated (pneumamnion 5±1mmHg), 7 in the 3-port and 5 in the single-port group. All but one in the 3-port group, survived. Compared to base line, three-port fetoscopy induced acidosis from 60 min onwards and hypercarbia from 30 min (Fig. 1), and in single-port fetoscopy acidosis occurred from 30 min onwards and hypercarbia from 60 min (Fig. 2). Fetal pO2, base excess, lactate and heart rate as well as maternal hemodynamics (systolic and diastolic blood pressures, heart rate) and acid-base status remained normal (Fig. 1&2). In the three-port technique, 5/7 (71%) closures were watertight as compared to 2/5 (40%) in the single-port group. Operation times were long and comparable (insufflation: 202±37min; fetal repair: 141±34 min in three port group; and 177±20 min and 137±17 min in the single port group). Under humidified and warmed CO2 pneumamnion, three-port and single-port fetoscopic SB closures induced fetal acidosis within one hour. In this experiment, watertightness was more frequently achieved with the three-port technique.View Large Image Figure ViewerDownload Hi-res image Download (PPT)