Table 1.

Baseline demographic and clinical data for each group

	Retrograde intrarenal surgery	Ultra-mini percutaneous nephrolithotomy	P Value
Number of patients	75	44
Mean age	57	54	0.87
BMI (kg/m)	29.6	32.6	0.5
Female (%)	36	40	0.77
Stone localisation  Upper calices  Middle calices  Lower calices  Pelvic	32% 4% 33% 31%	48% 5% 28% 19%	0.15 1.0 0.81 0.11
Median Stone burden (mm) (range)	7 (3 to 20)	9 (7 to 17)	0.21

BMI – body mass index