Explanation of this result may due to small casenumbers. Also the selection of operation type wasactually according to the surgeon’s experiences andclinical conditions, which might not be shown in medicaldocuments and led to overestimate one-stageoperation.The choices of operation method for complicateddiverticulitis are still controversial. Most surgeons fa-vor 1- and 2-stage operation instead of 3-stage operationdue to the development of new modalities, suchas laparoscopic surgery, antibiotics, and autosutures,etc. Also literature reviews published in 1980s supportedthat the 2-stage operation indeed had had a reductionof mortality to about half that for 3-stage operation.26,27 A more recent multicenter randomizedcontrolled trial found that a one-stage procedure significantlyreduced rates of postoperative peritonitisand emergent reoperation compared with a two-stageoperation, without adversely affecting operative mortality.In our results, we can find statistical significancein univariant analysis of stage operation and lesionsite (Table 5). This result revealed that the choice ofoperation method by surgeons was actually influencedby lesion site. Surgeons tended to perform2-stage operation for left side lesion rather than otheroperations; this may resulted from anatomic limits(insecured anastomosis, more easily to develop anastomosisinsufficiency, etc). We also found that therewas no phase I patient who underwent 2-stage operationand no phase III patient underwent 3-stage operation(Table 3).Theoretically, if we consideredphase III is more severe form of complicated diverticulitis,it should have multiple operations as 3-stage operation, but it was not the truth (Table 3). Afurther prospective study should be designed for confirmingthis hypothesis.Our study also showed significant relation betweenstage operation and hospital stay. The reasonmay be due to re-entry of the abdomen leading to longerrecovery; additionally, the patients’ condition mightbe different during each admission. Also, in our definition,Hartmann’s procedure and reversal of Hartmann’sprocedure are considered as a 2-stage operation,this may cause high admission duration in 2-stage operation group. The concept that surgical complicationsrate during each operation should be considered:the more operation patients take, the higherpossibility of getting complications.