Appropriate kidney stone size for ureteroscopic lithotripsy: When to switch to a percutaneous approach

Table 1 Natural history of asymptomatic kidney stones

Ref.	Study type	No. of patients	Follow-up	Disease progression (stone growth)	Symptomatic episode	Need for intervention
Glowacki et al[1]	Retrospective	107	31.6 mo	NA	31.8%	16.8%
Hübner et al[3]	Retrospective	80	7.4 yr	45%	68%	83%
Keeley et al[5]	Randomized prospective	200	2.2 yr	NA	21%	10%
Burgher et al[2]	Retrospective	300	3.26 yr	77%	NA	26%
Inci et al[4]	Retrospective	24	52.3 mo	33.3%	41.7%	11%

NA: Not available.

Table 2 Indications for active stone removal of kidney stones

Kidney stones
Stone growth
Patients at high risk for stone formation
Obstruction caused by stones
Infection
Symptomatic stones (e.g., pain, macrohematuria)
Stones ≥ 15 mm
Stones < 15 mm, if observation is not the option of choice
Patient preference
Comorbidity
Social situation of the patient (e.g., profession or travelling)

Table 3 Treatment outcomes of ureteroscopy for large kidney stones

Ref	Study type	No. of	Mean stone	Mean number	SFR after the	SFR after the
		patients	diameter	of operation	1st operation	2nd operation
Ricchiuti et al[12]	Single center, retrospective	23	3.1 cm	1.43	56.5%	73.9%
Breda et al[13]	Single center, retrospective	15	2.2 cm	2.3	60%	86.6%
Riley et al[14]	Single center, retrospective	22	3.0 cm	1.82	23%	86.4%
Hyams et al[15]	Multi center, retrospective	120	2.4 cm	1.18	83%	97.5%
Takazawa et al[10]	Single center, retrospective	20	3.1 cm	1.4	65%	95%

SFR: Stone free rate.

Table 4 Treatment outcomes of ureteroscopy for multiple kidney stones

Ref	Study type	No. of	Mean number	Mean number	SFR after the	SFR after the
		patients	of stones	of operation	1st operation	2nd operation
Breda et al[43]	Single center, retrospective, unilateral kidney	51	3.1	1.4	64.7%	92.2%
Herrera-Gonzalez et al[44]	Single center, retrospective, unilateral kidney	125	3.59	1	74.4%	NA
Huang et al[45]	Single center, retrospective, bilateral kidney	25	5.1	1.5	50%	92%

SFR: Stone free rate.