Kidney Stone Management

Introduction to Stone Removal

For renal caliceal stones larger than 10 mm, complex ureteroscopy with a flexible ureteroscope is required for successful removal, as simple ureteroscopy is insufficient due to the need for specialized equipment and techniques, as per the American Urological Association guidelines 1

Stones larger than 10 mm typically require fragmentation before extraction, and multiple passes may be needed to clear all fragments, with a higher risk of complications compared to simple ureteroscopy for distal ureteral stones 1
The location of the stone, such as in the upper/middle calyces or renal pelvis, influences the choice of treatment, with both SWL and URS being effective options, according to the American Urological Association 2

Complex ureteroscopy employs flexible ureteroscopes, Holmium:YAG laser for lithotripsy, stone retrieval devices, and a ureteral access sheath, which are necessary for accessing the intrarenal collecting system and navigating to calyces 1
Simple ureteroscopy uses rigid or semi-rigid instruments, which are insufficient for stones in the kidney due to the inability to effectively navigate to calyces 1

Complex ureteroscopy for proximal/renal stones carries higher risks, including ureteral injury (6%), stricture formation (2%), sepsis (3-4%), and urinary tract infection (4%), highlighting the need for careful planning and expertise 1
The abnormal course of the ureter in ectopic kidneys increases the risk of perforation, and access difficulties may require specialized techniques or approaches 1

All intraureteral manipulations must be under direct ureteroscopic vision, and fluoroscopic imaging alone is insufficient and dangerous, with blind basketing never being attempted 1
Appropriate antibiotic therapy should be administered if infection is suspected, based on mandatory urine culture results to rule out infection, and urgent drainage of the collecting system is necessary if infection is suspected 1, 3
The American Urological Association recommends SWL as the first choice for renal stones <15mm (Level of Evidence 1), and flexible URS is considered an equally effective option for stones <20mm 2
Percutaneous nephrolithotomy (PCNL) is generally reserved for stones >20mm or when other approaches fail, as recommended by the American Urological Association 2

For stones in the upper/middle calyces or renal pelvis, both SWL and URS are effective treatment options, according to the American Urological Association 2
For lower pole stones, URS may be preferred due to better clearance rates compared to SWL, as suggested by the American Urological Association 2
For patients with ectopic, low-lying kidneys and stones in the renal pelvis, flexible ureteroscopy (URS) with holmium laser lithotripsy is recommended as the first-line treatment, especially for stone sizes between 10-20 mm, due to high stone-free rates and the ability to navigate abnormal anatomy, as supported by the American Urological Association (AUA) with high success rates of 81-94% 4, 1

CT urography is essential for fully characterizing the ectopic kidney's anatomy, assessing vascular supply, and evaluating the ureter's course, which is often abnormal in ectopic kidneys 4
Renal function assessment, including serum creatinine, should be obtained to evaluate baseline function, and urine culture is mandatory prior to intervention to rule out infection 3, 1
Ureteral stent placement for 1-2 weeks is recommended due to anatomical abnormalities and the risk of edema and obstruction, with close follow-up and post-procedure imaging to confirm stone clearance 4
Periodic imaging is recommended to monitor stone position and assess for hydronephrosis, and close follow-up within 1-2 weeks is necessary to confirm stone passage or determine the need for additional intervention 1, 3

The American Urological Association recommends maintaining normal calcium intake of 1,000-1,200 mg/day (and not restricting calcium) to help prevent stone recurrence, limiting sodium intake to a target of 2,300 mg daily, and limiting oxalate-rich foods for patients with calcium oxalate stones 5
The American Urological Association suggests considering thiazide diuretics for patients with high urinary calcium and recurrent calcium stones, and alpha-blockers may be used after SWL to facilitate passage of stone fragments 5, 2