Stones exceeding 20 mm in diameter represent the upper range of kidney stone burden and require a more interventional approach than smaller calculi. The size threshold directly influences which procedural strategies are appropriate and what risks must be considered.
A kidney stone larger than 20 mm (greater than 2 cm) in diameter. At this size, non-invasive options carry a higher burden: shock wave lithotripsy alone often requires multiple treatment sessions and carries an increased risk of ureteral obstruction — including colic or steinstrasse — with a consequent need for adjunctive procedures.
When percutaneous nephrolithotomy (PCNL) is not an option, the protocol specifies alternative procedural interventions for stones in this size range — including endoscopic and extracorporeal approaches — with additional guidance on follow-up management. Full details, including the specific conditions under which each option applies, are in the structured protocol.