This study is designed to be a multicentre, prospective, comparative, randomised trial, evaluating the efficacy of two surgical strategies for the treatment of generalised peritonitis due to perforated diverticulitis. Results will be analysed according to an intention to treat principle (after selection and patient consent). Immediately before surgery, the patient will be randomly assigned to sigmoidectomy with primary anastomosis or to sigmoidectomy with primary anastomosis and diverting stoma. Sigmoidectomy will be performed through a midline laparotomy or laparoscopically according to the standard technique. In the control arm, a protective stoma will be performed at the end of surgery. A stoma reversal operation will be performed at least 3 months after the first operation and after performing a cologram by water soluble contrast between 4 and 8 weeks to check for the absence of fistula or stenosis at the level of the anastomosis. Stoma reversal will be performed with a trephine incision. Post-stoma closure follow-ups will be planned and all morbidity/mortality will be recorded. All patients will be examined at 6, 12, and 24 weeks after the initial surgery, in the surgical department where they were operated; a final study visit will be carried out 12 months (evaluation of primary endpoint) after surgery. The parameters explored at medical examinations will be: • Occurrence of complications • Quality of life assessment