ObjectiveTo explore risk factors and prognosis of unplanned reoperation in patients with malignant tumors of digestive tract. MethodsThe clinical data of patients with malignant tumors of digestive tract underwent unplanned reoperation who treated in the Department of General Surgery, the Northern District of the Shanghai Ninth People’s Hospital from January 2014 to December 2017 were retrospectively collected, and each operation was matched in a ratio of 1∶3 as a case-conontrol study object. The risk factors and prognosis of unplanned reoperation were analyzed by the basic information, surgical related informations, and postoperative relevant informations. ResultsThere were 33 cases of unplanned reoperation in the 588 patients with malignant tumors of digestive tract treated surgically, 8 cases died after the unplanned reoperation. The analysis results showed that the basic diseases, history of previous abdominal surgery, preoperative anemia, the first operative time >4 h and intraoperative blood loss ≥400 mL were the independent risk factors of the unplanned reoperations (P<0.050); the basic diseases, unplanned preoperative hemoglobin <90 g/L and intraoperative blood loss ≥400 mL were the independent factors of death for patients with unplanned reoperation (P<0.050). ConclusionsEffective intervention on independent risk factors associated with unplanned reoperation in patients with digestive tract malignant tumors can reduce incidence of unplanned reoperation in future and improve prognosis.