The ORION study protocol: impact of prior intraperitoneal versus extraperitoneal mesh placement on subsequent minimally invasive abdominal reoperations

Background: Ventral hernia repair is among the most common surgical operations worldwide. Mesh can be positioned in different anatomical planes; extraperitoneal placement is gaining popularity, whereas intraperitoneal placement is linked to long-term complications. Evidence comparing the long-term outcomes of intraperitoneal versus extraperitoneal placement remains limited. Objective: This study addresses that gap, also examining the management of recurrences and the potential neurological sequelae of surgery. Methods: The ORION study is a prospective, multicentre, observational study involving surgical centres across Europe. The study is addressed to patients who have previously undergone minimally invasive mesh-based ventral hernia repair, with either intraperitoneal or extraperitoneal mesh placement, and who are now undergoing minimally invasive abdominal surgery-either in an elective or emergency setting-for a hernia recurrence (Cohort B) or for other indications (Cohort A). Data will be collected between 1 March 2026 and 28 February 2027. Follow-up assessments at 30 and 90 days are planned only for patients enrolled in Cohort B. Discussion: The ORION study will provide data on the intraoperative consequences of prior intraperitoneal versus extraperitoneal mesh placement at subsequent minimally invasive abdominal surgery, and will describe recurrence patterns and management among patients reoperated for recurrent ventral/incisional hernia. Clinical trial registration: Identifier NCT07384962.