The two most common procedures used to remove kidney stones are shock wave lithotripsy (SWL) and ureteroscopy (URS). Both break stones into smaller pieces so they can leave your body, but they work in very different ways. SWL uses energy waves from outside your body, while ureteroscopy involves passing a thin scope through your urinary tract to reach the stone directly. A third procedure, percutaneous nephrolithotomy, is reserved for very large stones but comes up less often.
Shock Wave Lithotripsy (SWL)
Shock wave lithotripsy is the least invasive option. You lie on a treatment table while a machine sends thousands of high-energy pressure waves through your skin and into the kidney stone. These waves travel through soft tissue without causing damage, but when they hit the hard stone, they shatter it into sand-like fragments. Over the following days and weeks, those tiny pieces pass naturally through your urine.
SWL is typically used for stones larger than 5 millimeters (about the size of a pencil eraser) that won’t pass on their own, but generally smaller than 2 centimeters. Success rates vary widely, ranging from 30% to 90% depending on the stone’s size, location, and composition. Stones sitting in the lower part of the kidney tend to respond less well. For stones over 1 centimeter in that lower pole location, clinical guidelines recommend against using SWL as a first-line treatment because other procedures have higher clearance rates.
The procedure is usually done as an outpatient visit, meaning you go home the same day. You may receive sedation or light general anesthesia since the shock waves can be uncomfortable. Afterward, you’ll likely notice blood-tinged urine for a few days and some soreness around your back or abdomen where the waves passed through. Most people return to normal activities within a day or two.
Ureteroscopy (URS)
Ureteroscopy takes a more direct approach. A surgeon passes a thin, flexible tube called a ureteroscope through your urethra, up through your bladder, and into the ureter (the tube connecting your kidney to your bladder) until it reaches the stone. The scope has a tiny camera on the end, giving a live view of the stone. Once the scope is in position, a flexible laser fiber is threaded through it and used to break the stone apart. The fragments are then pulled out with a small basket-like instrument.
This procedure works well for stones in the ureter and kidney, and it handles a broader range of stone sizes than SWL. For stones up to 2 centimeters in the ureter, ureteroscopy is one of the standard options. It also generally has higher success rates than shock wave therapy, making it a preferred choice when SWL has already failed or when the stone’s location makes external waves less effective.
Ureteroscopy requires general anesthesia and is typically an outpatient procedure. One notable difference from SWL is that your surgeon will often place a temporary ureteral stent, a small flexible tube left inside the ureter to keep it open while swelling goes down. The stent stays in for a few days to a couple of weeks and is removed at a follow-up visit.
What a Stent Feels Like
The stent is often the most uncomfortable part of the recovery. While it’s in place, you may feel cramping, a frequent or urgent need to urinate, pain or discomfort when you pee, and bladder pressure. Some blood in your urine is normal during this time and for a few days after the stent comes out. Many people report feeling unusually tired while the stent is in. These symptoms resolve once it’s removed.
Percutaneous Nephrolithotomy (PCNL)
While SWL and ureteroscopy are the two procedures most people encounter, a third option exists for larger or more stubborn stones. Percutaneous nephrolithotomy involves making a small incision in your back and passing instruments directly into the kidney to break up and remove the stone. It’s the most invasive of the three, requiring general anesthesia and typically a hospital stay.
PCNL is recommended as first-line treatment for kidney stones larger than 2 centimeters. For stones between 1 and 2 centimeters, a smaller version called mini-PCNL may be offered and tends to produce higher stone-free rates than ureteroscopy. Because the procedure involves a surgical incision into the kidney, the risks are greater: potential complications include infection, blood clots, fluid buildup at the incision site, kidney damage, and the possibility of needing additional procedures. Some blood in your urine for a week or two afterward is expected.
How Stone Size Determines the Procedure
The single biggest factor in choosing a procedure is the size and location of your stone. Here’s how the current guidelines from the American Urological Association break it down:
- Stones under 1 cm in the lower kidney: SWL, ureteroscopy, or a percutaneous approach are all reasonable options.
- Stones over 1 cm in the lower kidney: PCNL produces the highest stone-free rates. SWL is not recommended as a first choice.
- Kidney stones between 1 and 2 cm: Mini-PCNL, when available, is preferred over ureteroscopy for better clearance.
- Kidney stones over 2 cm: PCNL is the recommended first-line treatment.
- Ureteral stones up to 2 cm: Either SWL or ureteroscopy is appropriate.
- Ureteral stones over 2 cm, or stones that failed previous treatment: A percutaneous approach is recommended.
Stone composition also matters. Some stones, particularly very hard ones, don’t break apart well with shock waves, making ureteroscopy or PCNL a better fit. Your imaging results (usually a CT scan) help determine the stone’s density, size, and exact position, all of which guide the decision.