Proposition for new terminologies in PCNL: what does 'ultra-mini-micro' actually mean?

Ever smaller miniaturised techniques are being developed for percutaneous nephrolithotomy (PCNL), with access sheaths now as small as 4.8Fr being used in adults. With the ever expanding use of the terms "micro" "mini" or "ultra" techniques, the terminology can be somewhat confusing. We propose a simple classification system to standardise the terminology for PCNL, encapsulating technological and procedural advancements.