Selective Suction Drainage Following Unilateral Biportal Endoscopic Decompression: a retrospective propensity score-matched cohort study

Abstract Background: The necessity of prophylactic drainage following unilateral biportal endoscopic (UBE) decompression remains controversial. This study aims to propose a novel MRI-based clinico-radiological grading system for postoperative local fluid collection (PLFC), evaluate the double-edged sword effect of drainage, and identify specific risk factors to establish a selective drainage algorithm. Methods: A retrospective cohort of 370 patients who underwent UBE decompression was enrolled and categorized into drainage and non-drainage groups. Propensity score matching (PSM) was utilized to balance baseline characteristics, yielding 110 highly comparable pairs (N=220). Perioperative parameters, visual analogue scale (VAS) for pain, and a novel 0–3 PLFC grading scale were evaluated. To capture unadulterated clinical predictors, multivariable logistic regression was performed on the unmatched non-drainage cohort (N=181) to identify independent risk factors for clinically significant PLFC (defined as Grade 2–3). Results: In the matched cohort, the drainage group exhibited significantly higher back pain on postoperative day 1 (VAS-B: 4.3 vs. 2.4, P < 0.001) but superior relief on day 2 after tube removal (VAS-B: 1.4 vs. 3.1, P < 0.001), demonstrating a distinct crossover effect. Furthermore, prophylactic drainage significantly reduced the incidence of clinically significant PLFC (Grade 2–3) (18.2% vs. 42.7%, P < 0.001) and accelerated first ambulation (20.9 vs. 27.6 h, P < 0.001). Multivariable regression on the unmatched non-drainage cohort identified extensive surgical decompression (ULBD) (Adjusted OR = 2.50, 95% CI: 1.26–4.96, P = 0.009) and high baseline BMI ≥ 25 kg/m² (Adjusted OR = 2.52, 95% CI: 1.30–4.87, P = 0.006) as robust independent risk factors for Grade 2–3 PLFC. Conclusion: Prophylactic drainage after UBE represents a critical clinical trade-off between mitigating symptomatic fluid accumulation and exacerbating acute tube-related back pain. We propose a selective drainage algorithm, strongly recommending routine drain placement for high-risk patients (BMI ≥ 25 kg/m² or undergoing ULBD) to prevent symptomatic PLFC and optimize rapid recovery, while safely omitting drains in low-risk patients to facilitate a tubeless Enhanced Recovery After Surgery (ERAS) pathway.