Shockwave lithotripsy (ESWL)

How ESWL works

The patient lies on a specialised table. A dedicated shockwave generator focuses high-energy acoustic pulses through the skin onto the target stone, which is kept in focus using fluoroscopy and/or ultrasound. The shockwaves fragment the stone into small pieces - typically 2 mm or less - that are then passed naturally in the urine over the following days to weeks.

Treatment takes about 30-45 minutes and is usually performed under sedation or a light general anaesthetic, so there is no memory of the treatment itself.

Who ESWL suits best

The best candidates are patients with:^{1, 2}

• Stones < 10 mm in the kidney, particularly in the renal pelvis or upper/mid calyces.
• Selected ureteric stones, especially proximal.
• Stones of moderate density on CT (Hounsfield units typically < 900-1000).
• Normal anatomy and normal body habitus.
• No active infection, no anticoagulation.

When ESWL is not the best choice

Guidelines advise against ESWL as first-line for:^{1, 2}

• Lower-pole kidney stones > 10 mm (PCNL or RIRS gives higher clearance).
• Non-lower-pole kidney stones > 20 mm.
• Very dense stones (> 1000 HU - often pure calcium oxalate monohydrate or cystine).
• Obstructed or infected stones (need drainage first).
• Uncorrected coagulopathy or ongoing anticoagulation.
• Pregnancy.
• Aortic or renal artery aneurysm in the shockwave path.

In these cases, flexible ureteroscopy with Holmium laser or PCNL is usually preferred.

Success rates - what to expect

• For stones < 10 mm, single-session stone-free rates of 60-80% are typical.¹
• For stones 10-20 mm, ureteroscopy generally gives higher single-session stone-free rates than ESWL - one meta-analysis reported an odds ratio of 2.00 (95% CI 1.29-3.12) in favour of flexible ureteroscopy for the 1-2 cm subgroup.³
• Some stones need more than one session to clear; a small proportion are resistant to shockwaves altogether and need a different approach.

The day of treatment

1. Admission

   Fasted, usually for 6 hours. A urine culture is confirmed negative in advance.

2. Treatment

   Sedation or light general anaesthetic. About 30-45 minutes on the lithotripter table. The stone is targeted using x-ray and/or ultrasound.

3. Recovery

   Usually home 1-2 hours later. Oral analgesia and fluids are given for the next few days. Passing fragments may cause intermittent loin discomfort.

4. Follow-up imaging

   At about 4-6 weeks, usually with a plain KUB and ultrasound, or CT if needed. If residual stone remains, a second session or a switch to ureteroscopy is considered.

Common side-effects

• Pink urine and small bruising of the skin in the first 24-48 hours - common and usually self-limiting.
• Intermittent colicky pain as fragments pass.
• Small risk of a fragment temporarily blocking the ureter (a "steinstrasse" - a street of stones).
• Small risk of urinary infection requiring antibiotics.
• Rare risk of a perinephric haematoma requiring a hospital stay.

Related pages

Patient information brochure

ESWL for kidney and ureteric stones PDF - BAUS patient brochure

References

1. Skolarikos A, et al. EAU Guidelines on Urolithiasis. 2025.
2. Pearle MS, et al. Surgical Management of Kidney and Ureteral Stones: AUA Guideline (2026).
3. Lv G, Qi W, et al. Safety and efficacy of extracorporeal shock wave lithotripsy vs flexible ureteroscopy: a systematic review and meta-analysis. Frontiers in Surgery. 2022;9:925481.