Comparative perioperative and oncological outcomes of the da Vinci Xi versus Si robotic surgical systems in rectal cancer surgery: a systematic review and meta-analysis.

The da Vinci Xi replaced the Si with a boom-mounted architecture intended to remove the re-docking and multiquadrant limits on pelvic access. Whether it changes outcomes in rectal cancer surgery is unresolved: existing syntheses pooled rectal with colonic resection. Five databases, Google Scholar and citation graphs were searched to August 2026, without language or design restriction, for comparative studies reporting outcomes separately by platform in rectal cancer resection. Screening, extraction and risk-of-bias assessment were done in duplicate. Random-effects models with a Hartung-Knapp adjustment were used; certainty was rated with GRADE. Eight non-randomised cohorts (843 patients; 380 Xi, 463 Si) were included. Pooling all five cohorts reporting operative time, the mean difference was - 27.7 min (95% confidence interval - 80.4 to + 25.0; I² 95%); restricted to the four reporting means with standard deviations, thus conditional on excluding the largest cohort, it was - 50.6 min (- 69.4 to - 31.7). Docking time was shorter with the Xi in all three reporting cohorts, which defined it differently or not at all. The evidence is very uncertain about the effect of platform on anastomotic leak (risk ratio 0.53, 0.24 to 1.14), complications, conversion, reoperation, margin involvement and specimen quality; certainty was very low throughout. The evidence is very uncertain about the effect of the da Vinci Xi compared with the Si on perioperative and oncological outcomes in rectal cancer, and functional outcomes have not been compared. Because the platforms were compared across periods, centres and levels of experience, no estimate isolates the platform.PROSPERO registration CRD420261480007, registered 18 August 2026, before data extraction.