The intervention consisted in the closure of the abdominal wall and skin by a second surgical team which included a board-certified surgeon and a resident.

During the baseline period, closure of the abdominal wall was performed by the main surgical team, the same team that performed the whole surgery.

The intervention consists of the exchange of the primary surgical team with a second surgical team that consists of one surgeon and one student. The first surgical team then may leave the operation theatre but is continuously accessible for questions.

SSI that occur after surgery will be assessed according to the criteria developed by the Centers for Disease Control and Prevention. Infections will be categorized as incisional (superficial or deep) infections or organ-space infections. Superficial SSI (type 1) involve only skin and subcutaneous tissue and exclude stitch abscesses. Deep SSI (type 2) involve deeper soft tissues, like fascia and muscle, at the site of incision. Organ-space SSI (type 3) involve any organ or body cavity

Observer receives the information during the follow-up phone call that the patient died. If patients do not respond to follow-up phone calls, five documented attempts to contact the patients followed by rapid contacts with the subject's general practitioner or other medical staff involved in the medical treatment of the patients, will be performed before loss to follow-up is documented. In addition, the Zivilstandsamt will be contacted once 3 months after surgery.