Procedure-Specific Postoperative Drainage Strategy in Transforaminal Full-Endoscopic Spine Surgery: A Quantitative Evaluation of Drain Output and Endoscopic Bleeding Findings.

BACKGROUND: Postoperative drain use after transforaminal full-endoscopic spine surgery (TF-FESS) remains controversial, and procedure-specific criteria are not well defined. This study aimed to determine whether postoperative bleeding risk-quantified by postoperative drain output and intraoperative endoscopic bleeding findings-differs by TF-FESS procedure and whether these metrics can inform a procedure-specific drainage strategy. METHODS: We retrospectively reviewed 100 consecutive TF-FESS cases: 65 managed with postoperative drains, and 35 managed without drains after an institutional policy change (limited to full-endoscopic discectomy [FED] and lumbar foraminotomy). Procedures included FED, full-endoscopic lumbar foraminotomy (FELF), full-endoscopic ventral facetectomy (FEVF), transforaminal full-endoscopic lumbar undercutting laminectomy (TELUL), and pars crisscross decompression (pars crisscross). Postoperative drain output was analyzed in the drain group. Intraoperative endoscopic bleeding was assessed at 3 standardized steps: approach/foraminoplasty (step 1), procedure-specific decompression (step 2), and final hemostasis (step 3). Multivariable analysis identified predictors of higher drain output. RESULTS: Drain output differed significantly among procedures (analysis of variance, P < 0.001). FED and FELF showed low drain output, whereas FEVF, TELUL, and pars crisscross showed higher drain output. Invisible bleeding during step 2 was more frequent in TELUL and pars crisscross. On multivariable analysis, TELUL and FEVF independently predicted higher drain output. In the drain-free subgroup (n = 35; FED/FELF), no patient developed neurological deterioration or symptoms requiring emergent hematoma evacuation. CONCLUSIONS: Bleeding risk in TF-FESS is strongly procedure dependent. Drain-free management was implemented only in a selected low-risk subgroup after a policy change; given the small sample size and the low baseline incidence of symptomatic hematoma, this cohort is not powered to assess safety outcomes, and drain-free observations should be interpreted as descriptive feasibility data. Postoperative drainage should be considered for advanced procedures involving epidural venous plexus manipulation and/or extensive cancellous bone exposure (FEVF/TELUL/pars crisscross). Given the nonrandomized, procedure-dependent drain policy, these findings are hypothesis generating. CLINICAL RELEVANCE: A procedure-specific, risk-stratified drainage approach may help optimize postoperative management and patient safety in TF-FESS.