In 2009, more than 448,000 spinal fusion procedures were performed in the United States. The complication rates reported in the literature for these procedures range from 4% to 19%, depending on the specific procedure, with the most common preventable complications including surgical site infections, bleeding, or thrombosis-type complications. Of these, the prevention of infection is a major concern for all spine surgeons. Recent studies have focused on the elimination of parasitic bacteria through preoperative skin disinfection and nasal treatment, the use of local antibiotics, perioperative glycemic control, and aseptic procedures. Intraoperative infections are estimated to account for approximately 22% of all infections; in the United States, for example, the number of intraoperative infections is approximately 300,000 to 500,000 of the approximately 27 million surgeries performed each year. Patient co-morbidities, as well as many preoperative, intraoperative, and postoperative factors, can have a significant impact on the incidence of infection. Infections pose a significant economic burden, both directly and indirectly, for the patient and the provider. Timely identification of infection is essential for treatment planning; however, it is difficult to establish validated definitive diagnostic indicators due to the wide variation in surgical technique, access, implant type, patient condition, and risk of infection. The diagnosis of infection is often difficult and requires a combination of clinical, imaging, and laboratory data for analysis. The most common clinical presentation is an increase in pain that occurs after normal postoperative pain relief and can last up to 2-3 weeks postoperatively. This pain can manifest as painful discomfort in the incision up to deep tissue pain with systemic symptoms such as fever and chills. Unexplained pain during the recovery period should be considered as an alarm for infection in the surgical area; new neurological symptoms may suggest infection in the surgical area; examination of the surgical area may reveal inflammatory changes, edema, pressure, and bloody or purulent exudate around the incision. However, it should be kept in mind that a dry and clean incision does not mean that infection can be ruled out. Laboratory tests are slightly more reliable for the diagnosis of infection. In general, depending on the extent of the surgery, the white blood cell count increases and the lymphocyte percentage decreases, and these indicators generally return to normal preoperative levels in 4-21 days. takahashi believes that persistent lymphocytopenia after lumbar internal fixation fusion indicates a possible complication of infection. In addition, acute reactants such as erythrocyte sedimentation rate and C-reactive protein may correlate with the degree of inflammatory response and the size of the procedure. The half-life of C-reactive protein is 2.6 days, which is relatively reliable and practical. In general, C-reactive protein should return to normal 1-2 weeks postoperatively, while hematocrit may remain elevated for several weeks. When high levels of C-reactive protein persist, even in the absence of associated clinical signs or atypical clinical signs, the possibility of infection should be alerted. Imaging manifestations usually lag behind clinical symptoms and laboratory tests. Radiography may suggest early pedicle screw loosening, lamina changes, and acute disc changes, whereas MRI provides more information on soft tissue and bone, and the results of these examinations must be read carefully because pathologic manifestations on MRI images are similar to normal postoperative inflammatory changes even with the help of contrast. MRI manifestations of infection include borderline enhancing fluid lesions, abnormal signal changes in the vertebral bone marrow, epidural abscess formation, and intervertebral disc enhancement. Other tests that can help in the diagnosis include CT and PET scans, which are limited by economic factors and the patient’s radiation exposure factors, with the risk of radiation exposure on PET scans approximating that of CT.