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

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. The diagnosis will be established by the surgeon investigator on clinical data, imagery and operative findings during a laparotomy or laparoscopy. After selection and patient consent and 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, with lateral to medial mobilisation of the left colon, mobilisation of splenic flexure and identification of left ureter. The rectosigmoid junction will be exposed and transected with a stapler. Proximal section will be performed on a healthy colonic segment. The anastomosis will be performed according to the surgeon investigator's preference (mechanical or manual anastomosis; end to end or side to end).

Decisions to clean the colon intraoperatively and to place a drain will be left to the surgeon's discretion. 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

Inclusion Criteria:

1. Age ≥ 18 years
2. Patients operated for purulent or fecal peritonitis (Hinchey grade III and IV) secondary to perforated diverticulitis of the left colon and treated by resection with primary anastomosis
3. Person informed and having signed his consent. If the patient is unable to sign his consent, the consent will be signed by his representative ((1) the trusted person, or failing that, (2) a family member, or (3) a relative of the person concerned) (Article L1122-1-1 of the CSP). In this case, consent to continue the study will subsequently be requested from the patient. --> In addition, due to the vital urgency represented by hospitalisation in intensive care for purulent or fecal peritonitis, inclusion without prior collection of the consent of the patient or his/her representative is possible in the case where the patient is not capable of giving consent and his/her representative is not present at the time of inclusion (Article L1122-1-3 of the CSP). In this case, the patient or his/her representative will be informed as soon as possible and his/her written consent will be requested for the possible continuation of this research and the use of the data concerning him/her.
4. Patient able to comply with the study protocol, in the investigator's judgment
5. Patient affiliated with, or beneficiary of a social security (health insurance) category

Non-inclusion Criteria:

1. Physical states that prevent patient participation (e.g. septic shock or multivisceral failure)
2. Steroid treatment > 20 mg daily
3. Prior pelvic irradiation
4. Immunocompromised status
5. Known progressive cancer
6. American Society of Anesthesiologists grade IV
7. Peritonitis secondary to perforated diverticulitis of the right colon
8. Patient is a pregnant (positive blood pregnancy test) or breastfeeding (lactating) woman or intending to become pregnant during the study
9. Person deprived of liberty by administrative or judicial decision or placed under judicial protection (guardianship or supervision)
10. Simultaneous participation in another interventional research

Exclusion Criteria:

1. Failure to obtain the consent of the patient or the patient's representative