Patients undergoing emergency surgery for peritonitis are at increased risk of abdominal wall-related complications. In patients with peritonitis the risk of incisional hernia (IH) is extremely elevated. The incidence of IH in patients operated with peritonitis is up to 54 %, compared with an incidence of 11-26 % in the general surgical population. Moreover, up to 24.1 % of patients with peritonitis undergoing emergency laparotomy may develop fascial dehiscence. The evaluation of quality of life of patients with IH showed lower mean scores on physical components of health-related quality of life and body image. The prophylactic mesh implantation demonstrated to reduce the incisional hernia rate in patients undergoing vascular or bariatric procedures. However, the intraperitoneal non absorbable mesh implantation in infected fields is generally considered at least of doubtful safety because of the theoretical increased risk of chronic mesh infection and enterocutaneous fistula. Most incisional hernias develop during the first three months after surgery, which represents the critical period for the healing of transected muscular and fibrous layers of the abdominal wall. However, most studies recommended a long-term follow up period of up to at least 5 years for midline abdominal incisions to determine the real incisional hernia rate. The midline abdominal incision is preferred in abdominal surgery, as it provides wide and rapid access compared other incisions. However, the incidence of incisional hernias is higher following midline abdominal incisions than in other abdominal incisions. In emergency surgery the midline incision in the majority of cases is a necessity. Several factors affect the process of wound healing: surgical site infection, poor surgical technique, and patient-related factors (i.e. peritonitis, old age, obesity, diabetes mellitus, nutritional deficiencies, hepatic cirrhosis, jaundice, renal impairment, malignancy, cardiac disease, chest problems, previous abdominal incisions, steroid therapy). Data about the use of biological prosthesis in infected fields are scarce and derive principally from case reports and case series. However, indications about their use and usefulness in infected fields have been recently published by the Italian Biological Prosthesis Working Group (IBPWG). A previously published prospective observational study evaluated the efficacy of implantation of biological prosthesis in high risk patients in order to reduce the incidence of incisional hernia. This study suggested the efficacy of this kind of prosthesis in reducing incisional hernia rate in patients with multiple risk factors. A recently published meta-analysis showed as the use of biological prosthesis in ventral hernia repair resulted in a lower infectious wound complication rate but in an similar recurrence rate. These results supports the application of biological prosthesis in high risk patients. One recent systematic review evaluated the positive effect on incisional hernia rate of the prophylactic mesh positioning in high risk patients. No randomized trials have been published since now about the use of biological prosthesis in contaminated or infected fields. The rationale of the trial is to evaluate the efficacy of the use of swine dermal collagen prosthesis implanted preperitoneally as a prophylactic procedure against incisional hernia in patients operated in urgency/emergency setting in contaminated/infected fields with peritonitis. The aim of the study is to reduce the incidence of incisional hernia from 50% to 20%.

Inclusion Criteria:

• Patients aged > 18 years old
• Clinical and/or laboratory and/or radiological evidence/signs of peritonitis of any origin (peritoneal reactivity, positive Blumberg sign, fever, free air/fluid in abdominal cavity, leucocytosis, increased C-Reactive Protein (CRP), lactic dehydrogenase (LDH), tachycardia, tachypnea, clinical or radiological evidence/suspect of bowel ischemia)
• Eventual strong suspect of possible bacterial translocation (reduction of the natural intestinal barrier against bacterial translocation, i.e. bowel ischemia, bowel overdistension, intestinal occlusion, etc.)
• Surgical indication for midline laparotomy independently from eventual previous laparotomies
• Informed consent

Exclusion Criteria:

• Patients aged < 18 years old
• Informed consent refusal
• No Clinical and/or laboratory and/or radiological evidence/signs of peritonitis of any origin
• Surgical indication for laparotomies other than midline one
• Pregnancy.

The study result will be used for oral presentation, publications and seminars. The personal patient's data will be not share for privacy.