Hot vs cold knife for endoscopic ablation of posterior urethral valves: a systematic review by the EAU-YAU paediatric urology working group.
INTRODUCTION: Posterior urethral valves (PUV) are the most frequent cause of congenital lower urinary tract obstruction in males. Despite early surgical ablation, up to 22% of patients develop chronic kidney disease and 11% progress to end-stage renal disease. Multiple endoscopic modalities have been described for valve ablation but the optimal technique remains uncertain. This systematic review aims to determine whether cold or hot knife ablation provides superior effectiveness for primary endoscopic treatment of PUV in a single surgical session. MATERIAL AND METHODS: A systematic search of PubMed and Embase databases was conducted to identify studies comparing cold and hot knife techniques for endoscopic ablation of PUV in children, covering all publications up to December 2025. The review was performed in accordance with PRISMA 2020 guidelines and was prospectively registered in PROSPERO (ID CRD420251180556). Original studies including patients <18 years who underwent primary valve ablation with postoperative cystoscopy or VCUG and ≥6 months of follow-up were included. Quality assessment was done using RoB 2.0 for randomized trials and MINORS for observational studies. RESULTS: A total of 1581 studies were identified, of which 26 met the inclusion criteria, comprising one randomized controlled trial, five prospective, and 20 retrospective studies constituting a sum of 1725 paediatric patients. The overall methodological quality of included studies was moderate, with marked heterogeneity in design, follow-up duration, and outcome reporting, limiting direct comparisons across series. Thus statistical analysis was not possible. Of these, 829 (48.1%) underwent cold valve ablation and 896 (51.9%) underwent hot ablation techniques. Within the cold group, most patients were treated with a cold knife (80.2%), followed by balloon dilatation (7%), the Mohan valvotome (6.5%), cold hook (5%), and, rarely, a modified venous valvulotome (1.3%). Among hot techniques, 32.8% of procedures were performed by electro-fulguration with a resectoscope, 29.4% using a Bugbee electrode, 23.8% with a hook electrode and 14% with laser-based systems. Follow-up ranged from 6 months to 22 years across studies. Single-session success rates for valve ablation ranged from 22% to 100% in the cold resection group and from 71.4% to 100% in the hot resection group. Reintervention for residual valves was reported in 0%-78% of cold cases and in 0%-28.6% of hot resections. Urethral stricture rates ranged from 0% to 11.1% after cold incision and from 0% to 23.8% after hot techniques. Reporting of postoperative outcomes such as urinary tract infection, incontinence, bladder dysfunction, vesicoureteral reflux (VUR) resolution, hydronephrosis improvement, and renal function varied widely among studies and was assessed using different methodologies. CONCLUSIONS: Both cold and hot ablation techniques for PUV achieved high single-session success rates and low complication rates. Cold resection appeared slightly safer, although this finding should be interpreted cautiously given the heterogeneity and observational nature of the available data.