When the stone cannot or should not be passed spontaneously, there are several options. The choice depends on: size; location; composition/hardness; anatomy; patient characteristics; equipment and experience.
The four techniques a student should know are: SWL · URS · RIRS · PCNL.
Extracorporeal shock wave lithotripsy (SWL) uses energy generated outside the body to fragment the stone. The fragments must then be passed spontaneously through the urinary tract.
Advantages: does not require endoscopic access to the stone; low invasiveness; can be performed on an outpatient basis in many patients.
Limitations: its efficacy depends on size, location, density/composition, anatomy, skin-to-stone distance, and patient characteristics. It may require more than one session.
Concept
SWL breaks the stone; the patient must pass the fragments.
Ureteroscopy allows an instrument to be introduced through the urethra → bladder → ureter until it reaches the stone.
The stone can be extracted, fragmented with laser energy, or treated with a combination of fragmentation and extraction.
Key advantage: it allows the stone to be treated under direct vision.
Compared with SWL, ureteroscopy offers a higher probability of becoming stone-free with a single procedure, although at the cost of a higher complication rate.
RIRS usually uses a flexible ureteroscope that can be advanced retrogradely into the kidney. It can reach the renal pelvis, calyces, and different intrarenal locations. Laser is usually used to fragment or dust the stone.
Concept for the student
RIRS allows stones inside the kidney to be treated through the natural urinary tract, without a percutaneous renal puncture.
In this technique the kidney is accessed through a percutaneous puncture. A tract is created from the skin to the renal collecting system, and the instruments are introduced through it.
It allows fragmentation and removal of a large stone burden. It is particularly relevant for large kidney stones.
The EAU continues to consider PCNL the standard procedure for large kidney stones. It is more invasive than RIRS or SWL, but it offers a great capacity to clear large stone volumes.
| Technique | How does it reach the stone? | Main idea |
|---|---|---|
| SWL | From outside the body | Breaks the stone with shock waves |
| Ureteroscopy | Urethra → bladder → ureter | Directly treats ureteral stones |
| RIRS | Urethra → bladder → ureter → kidney | Flexible endoscopy inside the kidney |
| PCNL | Skin → kidney | Percutaneous access for large stone burden |
The student does not yet need to memorize all the technical selection criteria. They should understand what each procedure does and how it reaches the stone.
1. Which technique accesses the kidney through a puncture from the skin?
A. SWL B. Ureteroscopy C. PCNL D. Cystoscopy
Correct: C.
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