Surgical Indications for Colonic Diverticular Disease Surgical indications for different types of colonic diverticulitis are currently changing. We herein discuss the current indications for surgery based on the classification by Hansen und Stock (types I-III, commonly used in German-speaking countries) and the distinction into 'mild' and 'severe diverticulitis' according to Ambrosetti (commonly used in English-speaking countries). Asymptomatic diverticulosis (type 0) almost never represents a surgical indication. Uncomplicated diverticulitis (type I) is also no indication for routine surgical resection. However, certain well-recognized risk factors for complicated diverticulitis should be taken into account (i.e. immunosuppression, steroid intake, rheumatoid diseases, and potentially - allergic predisposition) and may lead to surgical resection. Treatment of complicated diverticulitis types is controversial, especially regarding type IIA (phlegmonous) diverticulitis, which is subsumed under 'mild diverticulitis' according to Ambrosetti and for which antibiotic therapy is sufficient. There are, however, other data suggesting that type IIA is complicated and requires surgical resection. Data and recommendations regarding diverticulitis with covered (type IIB) or free perforation (type IIC) are more consistent, for which elective or emergency resection is indicated. New concepts with laparoscopic abdominal lavage alone are emerging, but the currently available data seem insufficient to make a recommendation for clinical use. The former recommendation to indicate surgical resection after the second attack of recurrent diverticulitis (type III) was abandoned and has been replaced by a risk-adapted strategy.