BackgroundThis study determines factors associated with deviation in length of hospital stay (LOS) from that determined by Diagnosis Related Groups. MethodsCohort study from a prospectively collected database including consecutive patients operated in a high-volume colorectal surgery department in 2009. ResultsFor 1461 included patients, average expected and actual LOS were 8.17 (IQR 4.7-11.9) and 8.31 (IQR 4-10) days, respectively. The most prominent factors associated with an increase of LOS from expected were parenteral nutrition (5.11 days) , emergency room admittance (3.67) and ileus (3.45) (all p≤0.001). Other independently associated factors included blood transfusion, anastomotic leak, sepsis, pulmonary embolism and surgeon. Patients with a higher severity-illness-index and postoperative intensive care stay had a lower than expected LOS. ConclusionsAfter colorectal surgery, several modifiable factors are associated with deviation of LOS from expected. An opportunity hence exists for reduction of LOS and reduce financial burden for hospitals in an era of pay-for-performance.