Arc of riolan-preserving splenic flexure takedown during anterior resection: Potentially critical to prevent acute anastomotic ischemia

INTRODUCTION: The Arc of Riolan is a strategic vessel that provides collateral mesenteric circulation in 10% of individuals. The importance of identifying and preserving the arc of Riolan in reducing the risk of ischemia to the proximal anastomotic segment after high ligation anterior resection was evaluated. TECHNIQUE: The arc of Riolan is a vessel that crosses anterior to the inferior mesenteric vein horizontally below the level of the pancreas. A retrospective review of all recorded videos of laparoscopic and robotic low and ultra-low anterior resections was performed in September to December 2012 and prospective evaluation in April to July 2013. The main outcome measures were arc of Riolan identifcation and preservation, and this was correlated with postoperative transmural colonic ischemia requiring surgical reintervention. From July 2013 onward, we routinely performed arc of Riolan-sparing anterior resections. RESULTS: Arc of Riolan was observed in 17.8% of cases. Between 2006 and 2012, before routinely looking for and preserving the arc of Riolan, our rate of acute colonic transmural ischemia requiring an emergency Hartmann procedure after anterior resection was 0.8% (6/723). Between 2012 and 2016, after we started performing arc of Riolan-sparing splenic flexure takedown, there were no cases of acute colonic transmural ischemia requiring surgical reintervention (0/576) after anterior resection. CONCLUSIONS: Recognizing and preserving the arc of Riolan, if visualized, during high inferior mesenteric vein ligation and splenic flexure takedown may be an important step in reducing the risk of acute colonic ischemia postanterior resection.