BACKGROUND: The aim of the present study was to compare the perioperative outcomes in patients who underwent planned open colectomy to those who were converted to an open.METHODS: All patients who underwent elective colectomy were identified from the American College of Surgeons National Surgical Quality Improvement Program using procedure-targeted database (2012-2014). Patients were divided into two groups: open (planned) versus converted. Perioperative outcomes were compared. A logistic regression model was used to calculate the propensity of unplanned conversion as opposed to open surgery.RESULTS: There were 21,437 patients; 17,366 (81.0%) in the open group and 4071 (19.0%) in the converted group. Operative time was longer in the converted group (212±99 vs. 182±111min, p<0.001), and hospital stay was longer in the open group (10.5±9.3 vs. 8.7±7.7days, p<0.001). Difference in morbidity rate (37.6% open vs. 34.5% converted, p<0.001) was no longer significant once confounders were adjusted. Specific complications were similar except for superficial surgical site infection (SSI) rate, which was significantly lower in open group (odds ratio 0.87, 95% confidence interval 0.76-0.97, p=0.010).CONCLUSIONS: The current study showed that conversion of laparoscopic colectomy to an open approach was associated with slight increase in superficial SSI rate but shorter hospital stay compared to planned open.