Just after signing a written informed consent to participate, patients will randomly be assigned either to the experimental group (Polihexanide bundle) or to the control group. Block randomization (blocks of 10 patients per single participating center) will be performed using an unstratified computer generated randomization list. All operations will be performed according to local criteria of the participating center. Hair removal will be accomplished on the day of surgery with electronic clippers. Alcohol-based solutions of chlorhexidine for surgical site skin preparation will be used. A first dose of perioperative i.v. antibiotics will be administered 30 minutes before skin incision (choice of the antibiotic according to local criteria) in all patients. Additional intraoperative doses will be administered for procedures exceeding two half-lives of the antibiotic. At the end of the operation, the peritoneal cavity will be rinsed routinely with 0.9% sodium chloride solution (normal saline, NS) at body temperature. Before closure of fascia, instruments and gloves will be changed. The eventual placement of drain(s) in the peritoneal cavity and/or creation of an intestinal stoma will be recorded. No subcutaneous suture or drainage will be done. Skin will be closed with either staples, intracutaneous running suture or interrupted sutures.

Potential patient-specific and intraoperative risk factors will be recorded: sex, age, body mass index, nutritional status, frailty, indication to surgery (benign vs. malignant disease), perioperative administration of steroids, renal failure and dialysis, cardiovascular or respiratory disease, American Society of Anesthesiologist class, bowel preparation, type of approach, operative time, presence of peritoneal cavity drainage. During the postoperative period, patients will be examined by the attending surgeon daily. Fever (central temperature \> 38 °C), pulse, abdominal signs, bowel movements, volume and aspect of drainage (if present) will be recorded daily. The local attending surgeon will make any decision for complementary exams and imaging according to his own criteria. The rate of any adverse event will be calculated and graded according to the Clavien-Dindo criteria \[19\] and to Japan Clinical Oncology Group Postoperative Complications (JCOG-PC) extended criteria \[20\], including all anastomotic leaks, wound infection (according to the definitions of the Centers for Disease Control and Prevention and wound culture), pneumonia (clinical symptoms, and physical and radiological examinations), central venous line infection (positive blood culture), urinary tract infection (positive urine culture with bacterial count). ERAS pathway items will be defined according to national \[27\] guidelines, measuring adherence upon explicit criteria. All data will be recorded for a minimum of 8 weeks (60 days) after surgery. PROM questionnaires will be administered to all enrolled patients four to one week before the planned operation, at discharge, and 6 to 8 weeks after the operation.

After anonymization, all data of each single case will be prospectively uploaded by local investigator(s) on a web-based database, protected by individual access credentials, and incorporated into a spreadsheet for data analysis. Any eventual discrepancy and/or mismatch will be checked, addressed and solved through strict cooperation between coordinating and local investigators.