This retrospective analysis evaluated 50 patients with gangrenous colonic volvulus two cases with ileocecal volvulus, one case with volvulus of the colon transverse and 47 cases with sigmoid volvulus- who were managed by primary resection with anastomosis (n = 21) or resection plus colostomy (n = 29) at Belén Hospital, Trujillo, Perú, from January 1, 1967 to July 31, 1993. The principal aim of the study was to identify by univariate analysis the combination of predictive risk factors for postoperative mortality. The following factors were associated with increased mortality: mean arterial pressure lower than 70 mmHg (p = 0.004), presence of purulent or fecaloid peritoneal fluid (p = 0.013) or evidence of macroscopic bowel perforation (p < 0.001). A method of quantifying the risk of mortality following gangrene of the loop using these factors was described. Each factor was given a weight value ranging from 0 a 2 (0 = major, 1 = moderate, 2 = minor) according to the severity of injury estimate. The sum of the individual factor scores comprised the final score of the Severity of Gangrenous Colon by Volvulus (S.S.G.C.). In this series the 30-day mortality rate was of 30%. A S.S.G.C. resulted greater than 4 in 34 (68%) of the patients. This was associated with a 9% mortality rate and contrasted to a 75% when the S.S.G.C. was equal to or less than 4. Mortality developed in 33% of the patients operated on using an immediate anastomosis (S.S.G.C., 4.2 +/- 0.99) and it was of 28% in those whose operation was resection plus colostomy (S.S.G.C., 3 +/- 0.87).(ABSTRACT TRUNCATED AT 250 WORDS)