The Four Generations of ESWL: How Shockwave Kidney Stone Treatment Evolved

Last updated: August 15, 2026

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Modern surgery aims to be as non-invasive as possible. Kidney stones were once treated by open surgery; today there are several ways to remove a stone with a small wound or none at all. Extracorporeal Shockwave Lithotripsy (ESWL) is one of them, and it is the subject of this article. The first machine was developed in Germany after the Second World War, exploiting the fact that focused shockwaves can pass through skin without breaking it. The technology has since been reinvented four times. This article traces what each generation changed.

Please note: this article is a history of the technology, written from my years of stone practice in Cambodia. It does not describe the equipment at any one hospital today. ESWL at Bangkok Hospital Headquarters is currently performed with a 3rd-generation lithotripter, as a daycare procedure with short-acting intravenous analgesia or light sedation for comfort.

1st Generation ESWL

The first-generation machine was enormous — roughly the size of a truck — and the patient had to be lowered into a full water tank for treatment. General anesthesia was mandatory, and delivering care inside a tank of water made everything about the procedure difficult.

2nd Generation ESWL

The second generation solved the water tank problem. It introduced the first “dry” technique, which made the procedure considerably more tolerable. The drawbacks remained, though: the machine was still bulky, the treatment was still uncomfortable, and anesthesia was still required because of the pain.

3rd Generation ESWL

The third generation is the workhorse of stone practice around the world today, and it is the machine used at Bangkok Hospital Headquarters. It is far more compact, and the patient simply lies on a treatment table. Because some shockwave pulses can still drift off target and cause discomfort in the kidney, patients are given short-acting intravenous analgesia or light sedation during the session. It remains an effective, well-established treatment for appropriately selected stones.

4th Generation ESWL

The defining feature of the fourth generation is an auto-tracking system that follows the stone as it moves with the patient’s breathing. I introduced this technology to Cambodia at Royal Phnom Penh Hospital in 2018, after training at Chang Gung Memorial Hospital in Taiwan — at that time it was the first and only 4th-generation lithotripter in the country.

In the original Taiwanese report, the 4th-generation machine achieved a 98.5% shockwave hit rate, against 82.6% for a 3rd-generation machine. Fewer missed pulses means less pain, so treatment can often be given with minimal or no sedation. The same report described an 80% stone-free rate at three months of follow-up for a 12 mm stone.

Over roughly two years of using that machine in Cambodia, our stone-free rates were 84% for stones under 1 cm, 77% for 1–2 cm, and 60% for stones above 2 cm, with high patient satisfaction and no serious complications. Those are Royal Phnom Penh figures from that period, not current Bangkok Hospital data.

Every stone treatment has trade-offs, and ESWL is no exception. Its distinctive advantage — true of both 3rd- and 4th-generation machines — is that it is the least invasive option available and is done as daycare, so it is usually worth considering before moving to an operation. Which approach suits you depends on the size, density and position of your stone, and that is a conversation to have with your urologist.

Post-ESWL patient instructions are provided here.

How the 4th Generation ESWL works is explained here.

For kidney stone evaluation or ESWL treatment, Dr. Soarawee Weerasopone offers specialist consultations at Bangkok Hospital Headquarters. Book a Consultation. Appointments at Samitivej Sriracha Hospital can be arranged by calling the Urology department on 088-022-1445.

Frequently Asked Questions

What is 4th Generation ESWL?

4th Generation ESWL (Extracorporeal Shock Wave Lithotripsy) is the most recent evolution of non-invasive kidney stone treatment. Like every generation before it, it uses focused shock waves delivered through the skin to break a stone into small fragments that then pass naturally in the urine. What distinguishes it is an auto-tracking system that follows the stone as the patient breathes, giving a reported 98.5% shockwave hit rate — which in turn means less discomfort and, in many centres, treatment with minimal or no sedation.

Does ESWL hurt, and is anesthesia required?

General anesthesia is not required for ESWL on modern machines, but comfort measures differ by generation. With a 4th-generation system the pulses rarely miss the target, so many centres treat with minimal or no sedation and the patient stays awake. With a 3rd-generation lithotripter — the machine used at Bangkok Hospital Headquarters — patients are given short-acting intravenous analgesia or light sedation so the session is comfortable. In both cases ESWL is a daycare procedure with no hospital admission.

What kidney stone sizes can be treated with ESWL?

ESWL works best for small to medium kidney stones, and European Association of Urology guidance recommends it for stones under 2 cm. In my own Cambodian series using a 4th-generation machine, stone-free rates were approximately 84% for stones under 1 cm, 77% for 1–2 cm, and 60% for stones larger than 2 cm. For larger or more complex stones, an endoscopic operation is the alternative. Guidelines list percutaneous nephrolithotomy (PCNL) as first-line above 2 cm, but it requires a tract created through the flank into the kidney; my own preference is to attempt retrograde intrarenal surgery (RIRS) with the holmium laser wherever it is feasible, since modern flexible ureteroscopy reaches stones of almost any size through the natural urinary passage with no incision. Stone density and position matter as much as size.

How long does it take for the stone to disappear after ESWL?

Most patients pass the stone fragments within a few days to several weeks after the procedure. Published data report that a 12 mm stone reaches an 80% stone-free rate at three months of follow-up. Drinking plenty of water and following the post-ESWL patient instructions helps the fragments pass naturally and reduces the risk of complications.

Disclaimer: This content is written and reviewed by Dr. Soarawee Weerasopone, a board-certified urologist at Bangkok Hospital Headquarters. It is intended for educational purposes only and does not constitute medical advice. No medical advice, diagnosis or prescription is provided through personal messaging channels. Always consult a qualified healthcare professional before starting any medical treatment.