Navigating Uncharted Territory in Surgical Innovation: A systematic review of non-standard Metabolic Bariatric Surgery procedures

BACKGROUND: Surgical innovation often outpaces robust evaluation. This study used metabolic bariatric surgery (MBS), a field of high-intensity innovation, as a case study to evaluate reporting standards and ethical oversight for experimental procedures within surgery. METHODS: We conducted a systematic review in accordance with PRISMA 2020 guidelines. We searched PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library, and Embase from January 2000 to December 2024 using terms related to metabolic bariatric surgery, surgical innovation, and non-standard intestinal bypass procedures. We included original studies reporting first-in-human or early clinical series of non-standard primary MBS involving significant intestinal modification, and excluded reviews, editorials, conference abstracts, revisional surgery, purely restrictive procedures, and device-based interventions. Two reviewers independently screened studies, extracted data on publication timing, patient numbers, follow-up, ethical approval, and trial registration, and assessed risk of bias using the Newcastle-Ottawa Scale, Joanna Briggs Institute checklist, and ROBINS-I tool. RESULTS: From 57 included studies (10,754 patients), the median time from first human operation to publication was 5 years (IQR 3-8 years). The median initial cohort size was 39 patients (range 1-1074 patients). Institutional review board or ethical approval was reported in 47/57 studies (82%), while prospective clinical trial registration was documented in only 6/57 studies (11%). Methodological quality was low (mean Newcastle-Ottawa Scale score 5.0/9), with 56 of 57 studies judged at high risk of bias. Out of 57, studies, only 15 (26%) reported outcomes at ≥3 years, and 8 studies (14%) at ≥5 years. CONCLUSION: This MBS case study reveals delayed publication and a widespread lack of prospective trial registration, exposing over 10,000 patients to experimental procedures outside a transparent research framework. These findings highlight a systemic failure in surgical innovation governance and underscore an urgent need for a cultural shift towards mandatory, prospective oversight frameworks to ensure patient safety and credible evidence generation.