BACKGROUND: To assess the safety and efficacy of flush endovenous laser ablation (fEVLA) in the treatment of chronic venous insufficiency (CVI). METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a systematic review aiming to identify studies published from inception to March 2024 was conducted. The investigation covered single-arm studies and studies comparing fEVLA to standard EVLA (sEVLA). The primary endpoint was endovenous heat-induced thrombosis (EHIT) class ≥ II. RESULTS: Eleven studies encompassing 2738 patients and 3147 truncal veins were included. The pooled EHIT ≥ II was 1.37% (95% CI: 0.57-3.28). Meta-regression identified an association between linear endovenous energy density (LEED) applied at the saphenofemoral junction (SFJ) and EHIT ≥ II outcomes (β = 0.011, P <
0.01). The pooled medium-term great saphenous vein (GSV) occlusion was 97.59% (95% CI: 94.89-98.88). The pooled and crude deep vein thrombosis (DVT) and pulmonary embolism (PE) estimates were 0.97% (95% CI: 0.64-1.47) and 0.04%. The comparative analysis regarding GSV occlusion, odds ratio (OR) 3.26 (95% CI: 0.76-13.97) and refluxing anterior accessory saphenous vein (AASV), risk ratio (RR) 0.45 (95% CI: 0.11-1.77) suggested a nonstatistically significant trend favoring fEVLA. Nonstatistically significant differences were identified in terms of EHIT ≥ II between the techniques, RR 1.00(95% CI: 0.18-5.53). Statistically significant differences favoring fEVLA were identified in terms of proximal groin recurrence RR 0.35 (95% CI: 0.16-0.80) and stump length (mean difference) MD -7.23 (95% CI: -11.59to-2.88). CONCLUSION: This review has demonstrated the safety of fEVLA while also suggesting a potentially improved efficacy of fEVLA over sEVLA in terms of proximal groin recurrence. Moreover, the trend indicating fEVLA's superiority in terms of GSV occlusion and the occurrence of new-onset AASV reflux merits further research.