In a study involving neurosurgeons worldwide, it was reported that most surgeons preferred the use of drains (186, 80.5%) and subfascial drains (169, 73.2%), with 52.87% of surgeons discontinuing drains based on time and 27.7% based on drainage volume (Cabrera et al. 2025). While the Enhanced Recovery After Surgery (ERAS) protocol does not recommend routine wound drainage for short-segment lumbar fusion surgery (Evidence Level Moderate, Recommendation Strength), the timing of drainage termination is based on drainage output (if drainage is below 50 ml) or based on postoperative days (day 2) (Han et al., 2024; Smith et al., 2019). We believe that further studies are needed to determine which patient groups require drains preoperatively and how long drains should remain in place postoperatively. This study, which aims to predict the amount of drainage during the perioperative period, will attempt to predict both the selective use of drains and how long to wait before discontinuing drainage in patients with drains. Lumbar subcutaneous fat thickness, previously used as a predictor of surgical site infections, will be tested for the first time in our study to determine whether it is a predictor of drainage output.