Perioperative blood transfusion increases risk of surgical site infection after bariatric surgery

•Bariatric surgery patients who receive a perioperative blood transfusion are at higher risk of developing surgical site infections.•Organ space infections are the most common surgical site infection in bariatric surgery patients who receive a perioperative blood transfusion.•The majority of organ space surgical site infections occur after gastric bypass. Surgical site infection (SSI) is an important marker of postoperative morbidity and overall quality of care. Transfusion-related immunomodulation can lead to weakened immunity in response to blood transfusion and predispose patients to SSIs. The aim of this study was to determine the impact of perioperative blood transfusions on SSIs in bariatric surgery patients. National data set. The American College of Surgeons National Surgical Quality Improvement Program data sets were queried for laparoscopic and open bariatric operations between 2012 and 2014. Univariate analyses identified perioperative variables associated with postoperative SSIs. Multivariate regression analyses determined the effect of perioperative blood transfusions on postoperative SSI. The study cohort included 59,424 patients: 480 (8.1%) biliopancreatic diversions, 28,268 (44.2%) gastric bypasses, 30,258 (50.9%) sleeve gastrectomies, and 418 (7.0%) bariatric revisions. Of the patients, 1107 (1.9%) developed a SSI: 662 (1.1%) superficial, 89 (0.1%) deep, and 356 (.6%) organ space. Patients receiving a perioperative blood transfusion were more likely to develop any type of SSI, organ space being most prevalent (Fig. 1). Among organ space SSIs, 198 (55.6%) were gastric bypasses and 125 (35.1%) were sleeve gastrectomies. Bariatric surgery patients who receive a perioperative blood transfusion are at higher risk of developing SSIs, particularly organ space. The majority of organ space SSIs occur after gastric bypass, likely secondary to infected intra-abdominal hematomas. Close monitoring of postoperative signs of infection in these patients is important to determine if additional interventions are warranted.