The Use of Knives With Versus Without Integrated Water-jet Function During Peroral Endoscopic Myotomy for Patients With Achalasia: A Meta-analysis.

Background: Peroral endoscopic myotomy (POEM) is a well-established endoscopic treatment for achalasia, utilizing an endoscopic knife for dissection. Recently, new knives with an integrated water-jet (WJ) function have been introduced. This study aims to compare the technical, perioperative, and late postoperative outcomes between WJ knives and conventional (C) knives, which lack the WJ function, through a pairwise meta-analysis of published comparative studies.

Methods: We conducted a systematic literature review following PRISMA guidelines to identify studies directly comparing knives with versus without a WJ function in POEM for achalasia. A random-effects model was employed, using odds ratios for dichotomous data and mean differences for continuous data as effect size metrics.

Results: The use of WJ knives demonstrated statistically significant reductions in the mean number of intraoperative instrument exchanges, mean intraoperative use of coagulation forceps, and operative times compared to the use of C knives. There were no significant differences in terms of the incidence of adverse events, subcutaneous emphysema, or mean hospital length of stay (LOS). Clinical success, defined as a postoperative Eckardt score <3, mean postoperative Eckardt scores, and the incidence of GERD requiring proton pump inhibitors (PPI) also showed no significant differences.

Conclusions: The use of water-jet (WJ) knives demonstrates comparable efficacy to conventional (C) knives, with superior efficiency reflected in reduced operative time and fewer intraoperative instrument exchanges. In addition, in terms of safety, the lower use of coagulation forceps with WJ knives suggests reduced intraoperative bleeding. However, no significant differences were observed between the groups in terms of length of stay (LOS) and adverse events, despite a trend toward reduction. A larger number of studies with greater sample sizes is required to better assess potential differences in safety between the use of WJ and C knives.