Factors affecting colectomy rate were studied in a retrospective population based series of 1586 patients with ulcerative colitis, in Stockholm County during 1955-84. Five hundred and sixty eight patients (36%) had total colitis at diagnosis, 603 patients (38%) left sided colitis, and 397 patients (25%) proctitis. During a median period of observation of 13 years 514 patients were treated by colectomy. The five, 10, and 25 year cumulative colectomy rate were 20% (CI 18-22%), 28% (CI 26-30%), and 45% (CI 41-49%) respectively. The main factor affecting the colectomy rate was the extent of disease at diagnosis. Patients with total colitis showed a five, 10, and 25 year cumulative colectomy rate of 32% (CI 28-36%), 42% (CI 38-46%), and 65% (CI 58-72%) respectively. Ten per cent of the 1586 patients had a colectomy during the first year after diagnosis, 4% during the second year and 1% during subsequent years VSports手机版. The age at diagnosis and sex did not affect the cumulative colectomy rate. Elective colectomy was performed in 322 cases (63%) and acute colectomy in 192. The duration of disease before colectomy fell during the study period due to a more standardised criteria for colectomy in severe attacks. One hundred and twenty nine (66%) of the acute colectomies were performed within two years from diagnosis. .