A number of nontraumatic acute abdomen can result in peritonitis leading to sepsis. In emergent conditions, various procedures like segmentary colectomy and/or subtotal colectomy with anastomosis, Hartmann's procedure, transverse colectomy, and/or expandable metallic stent (SEMS) placement can be performed, considering the status of the patient and the facilitaties of the institution. In our study, we examined the cases diagnosed as acute abdomen without the history of trauma, which had lead to a procedure requiring colostomy. We retrospectively analysed 105 cases of nontraumatic acute abdomen, resulted in a procedure requiring colostomy. American Society of Anesthesiologists (ASA) scoring and Mannheim Peritonitis Index (MPI) were used in the evaluation of the risk of mortality and morbidity. There were colonic perforations of rectosigmoid tumor in 66 cases (62.8 %), sigmoid volvulus in 10 cases (9.5 %), colonic anastomotic leakage in 9 cases (8.5 %), intestinal adhesions in 8 cases (7.6 %), mesenteric ischemia in 5 cases (4.7 %), gynecological diseases in 3 cases (2.85 %), strangulated hernias in 3 (2.85 %), and Ogilvie syndrome in 1 case (0.95 %). Rate of morbidity was found to be 25.7 %, while mortality occurred in 2.8 % of the cases. Cases with mortality and morbidity had ASA scores above two and MPI scores above 23. Anastomotic leakage was the only reason of mortality. In nontraumatic occasions, the management and prognosis of cases with peritonitis, general status of the patients play major roles. The prognosis rates of morbidity and mortality can be highly predicted when ASA and MPI scores are evaluated together.