Laser technology advancements have been a cornerstone in urology, with the introduction of smaller core size fibers and newer lasers like thulium fiber lasers. Laser fiber core size plays an important role in the outcome of endourological procedures. This systematic review evaluates the impact of laser fiber core size on energy delivery, fiber tip degradation, thermal safety, durability, fracture resistance, retropulsion, and flexibility in endourological procedures

A comprehensive literature search was conducted using PubMed and Cochrane databases to identify articles that compared laser fiber core sizes. The initial search produced 1,148 articles, which were screened for relevance. After screening, 109 duplicates were removed, and 996 articles were excluded based on title and abstract screening. After the exclusion of two irretrievable articles, 43 articles underwent full-text review. Thirty articles that lacked relevant parameters or were review articles were removed. One article was added manually, and a total of 14 studies were included for review.

Smaller core fibers (≤300 μm) provide higher energy delivery and greater flexibility but are prone to tip degradation and exhibit lower durability under high-power settings. Larger core fibers (≥300 μm) demonstrate superior energy efficiency, reduced tip degradation, and enhanced fracture resistance. Thermal safety is linked closely to irrigation and fiber size. Smaller fibers maintain safer temperatures under irrigation. Retropulsion is less pronounced in smaller and larger fibers compared to medium-core fibers (365–550 μm). Bubble formation during Thulium fiber laser (TFL) procedures is affected by fiber core size. Smaller fibers (150 μm) produce larger bubbles than Larger fibers (272 μm). TFL showed better flexibility, lower fracture rates, and reduced retropulsion compared to holmium: yttrium-aluminum-garnet (Ho: YAG) lasers.

Laser fiber core size has a significant influence on energy delivery, durability, thermal safety, flexibility, and retropulsion, all of which influence surgical outcomes. Smaller fibers (≤300 μm) demonstrated superior energy transmission and flexibility, making them ideal for lithotripsy. Larger fibers (≥300 μm) showed greater energy efficiency, durability, and reduced tip degradation, favouring high-power applications such as laser enucleation of the prostate. Larger fibers require proper irrigation for thermal safety. TFL showed better flexibility, lower fracture rates, and reduced retropulsion compared to holmium: yttrium-aluminum-garnet

Selecting the appropriate fiber size for each specific procedure is essential to optimizing surgical efficiency and improving patient outcomes.