Risk factors for abdominal surgical site infection after exploratory laparotomy among combat casualties

BACKGROUND: Surgical site infections (SSIs) are well-recognized complications after exploratory laparotomy for abdominal trauma; however, little is known about SSI development after exploration for battlefield abdominal trauma. We examined SSI risk factors after exploratory laparotomy among combat casualties. METHODS: Military personnel with combat injuries sustained in Iraq and Afghanistan (June 2009 to May 2014) who underwent laparotomy and were evacuated to participating US military hospitals were included. Log-binominal regression was used to identify SSI risk factors. RESULTS: Of 4,304 combat casualties, 341 patients underwent a total of 1,053 laparotomies. Abdominal SSIs were diagnosed in 49 patients (14.4%): 8% with organ space SSI, 4% with deep incisional SSI, and 4% with superficial SSIs (4 patients had multiple SSIs). Patients with SSIs had more colorectal (p < 0.001), small bowel (p = 0.010), duodenum (p = 0.006), pancreas (p = 0.032), and abdominal vascular injuries (p = 0.040), as well as prolonged open abdomen (p = 0.004) and more infections diagnosed before the SSI (or final exploratory laparotomy) versus non-SSI patients (p < 0.001). Sustaining colorectal injuries (risk ratio [RR], 3.20; 95% confidence interval [CI], 1.58–6.45), duodenum injuries (RR, 6.71; 95% CI, 1.73–25.58), and being diagnosed with prior infections (RR, 10.34; 95% CI, 5.05–21.10) were independently associated with any SSI development. For either organ space or deep incisional SSIs, non–intra-abdominal infections, fecal diversion, and duodenum injuries were independently associated, while being injured via an improvised explosive device was associated with reduced likelihood compared with penetrating nonblast (e.g., gunshot wounds) injuries. Non–intra-abdominal infections and hypotension were independently associated with organ space SSIs development alone, while sustaining blast injuries were associated with reduced likelihood. CONCLUSION: Despite severity of injuries and the battlefield environment, the combat casualty laparotomy SSI rate is relatively low at 14%, with similar risk factors and rates reported following severe civilian trauma.