The Intraoperative Wound Irrigation to Prevent Surgical Site Infection After Laparotomy (IOWISI) trial, conducted by the CHIR-Net, aimed to evaluate the effectiveness of intraoperative wound irrigation with polyhexanide solution in reducing surgical site infections (SSIs) after laparotomy. The study was a multicenter, randomized, controlled trial involving 689 adult patients undergoing laparotomy in 12 German hospitals from September 2017 to December 2021. Patients were randomized to receive either polyhexanide 0.04%, saline, or no irrigation. The primary endpoint was the incidence of SSI within 30 days postoperatively, defined by the US Centers for Disease Control and Prevention. The results showed that the overall incidence of SSI was 11.8% (81 out of 689 patients). There was no significant difference in SSI rates between the polyhexanide group (10.6%, 31 out of 292 patients), the saline group (12.5%, 37 out of 295 patients), and the no irrigation group (12.8%, 13 out of 102 patients). The hazard ratios (HRs) for polyhexanide compared to no irrigation and saline were 1.23 (95% CI 0.64-2.36, P = .54) and 1.19 (95% CI 0.74-1.94, P = .47, respectively). The incidence of serious adverse events did not differ among the three groups. The study concluded that intraoperative wound irrigation with polyhexanide solution did not reduce the incidence of SSI compared to saline or no irrigation in clean-contaminated open abdominal surgical procedures. The findings suggest that more clinical trials are needed to evaluate the potential benefits of polyhexanide in contaminated and septic procedures, including emergency settings.The Intraoperative Wound Irrigation to Prevent Surgical Site Infection After Laparotomy (IOWISI) trial, conducted by the CHIR-Net, aimed to evaluate the effectiveness of intraoperative wound irrigation with polyhexanide solution in reducing surgical site infections (SSIs) after laparotomy. The study was a multicenter, randomized, controlled trial involving 689 adult patients undergoing laparotomy in 12 German hospitals from September 2017 to December 2021. Patients were randomized to receive either polyhexanide 0.04%, saline, or no irrigation. The primary endpoint was the incidence of SSI within 30 days postoperatively, defined by the US Centers for Disease Control and Prevention. The results showed that the overall incidence of SSI was 11.8% (81 out of 689 patients). There was no significant difference in SSI rates between the polyhexanide group (10.6%, 31 out of 292 patients), the saline group (12.5%, 37 out of 295 patients), and the no irrigation group (12.8%, 13 out of 102 patients). The hazard ratios (HRs) for polyhexanide compared to no irrigation and saline were 1.23 (95% CI 0.64-2.36, P = .54) and 1.19 (95% CI 0.74-1.94, P = .47, respectively). The incidence of serious adverse events did not differ among the three groups. The study concluded that intraoperative wound irrigation with polyhexanide solution did not reduce the incidence of SSI compared to saline or no irrigation in clean-contaminated open abdominal surgical procedures. The findings suggest that more clinical trials are needed to evaluate the potential benefits of polyhexanide in contaminated and septic procedures, including emergency settings.