Shockwave lithotripsy (ESWL) for kidney stones: what to expect and how safe it is

A machine produces shockwaves, in the leaflets described as coming from an electro-magnetic coil, and focuses them on the stone. X-ray or ultrasound is used to line up the stone. Warm water is used to couple the treatment head to your back, and the pulses pass through the skin so that the stone cracks into fragments.

Nothing enters the body. That is the main attraction compared with telescope surgery, but the method works better for some stones than others. Size, position, and hardness all matter, and the kidney lies behind the bowel in a way that makes some positions harder to reach than others.

Specialists usually consider ESWL for stones in the kidney or the upper ureter of a size that fits within what the machine can break. Small stones are often left to pass without treatment, and very large or very hard stones are more likely to need telescope surgery or a keyhole operation through the back.

Trust leaflets list practical exclusions. You should not have treatment if you are, or might be, pregnant, because X-rays are used. A urine infection should be cleared first. If you take warfarin, aspirin, clopidogrel or a newer anticoagulant, you need instructions from the stone team about whether and when to stop, since bleeding around the kidney is the main danger; one leaflet asks for a blood test shortly before treatment.

• Tell the team about any bleeding disorder or tendency to bruise easily.

• Ask whether the stone is likely to respond, since hard stones sometimes do not break up.

Unlike most operations you can usually eat and drink as normal before treatment. Bring comfortable clothes and a list of your medicines. Have painkillers at home, because the aching afterwards can run for several days.

Your letter may ask you to see your GP about an infection first or to speak to the stone nurse about blood thinners. Do these things early, because a missed instruction is one of the commonest reasons a session is postponed.

You lie on a treatment couch, the nurse checks your details, and you are given the pain relief you were prescribed. The radiographer or doctor locates the stone and starts at a low intensity, building up as you get used to it. People describe a tapping or flicking sensation that can be uncomfortable but tends to be tolerated.

Staff will ask how you are coping and can pause or adjust. The machine may be stopped while the stone is re-positioned, because breathing moves the kidney. A short rest follows, and you are allowed home once you have passed urine and feel steady. Do not drive yourself home; one trust asks for no driving for 24 hours.

Drink plenty of fluids, with one trust suggesting two to three litres a day, to help carry fragments out. Take paracetamol or an anti-inflammatory as advised. Blood in the urine is expected for a short time, and the leaflets describe a pale pink colour for around two to three days. Bruising on the skin over the kidney can appear.

As fragments pass you may feel waves of colicky pain in the side. This is not a sign that something has gone wrong, but it is also a reason to keep painkillers at hand and to know when to ring for help. The stone team may arrange a scan or X-ray to see whether everything has cleared before deciding on a second session.

Common effects described in trust leaflets include blood in the urine, kidney-area pain, bruising, urine infection that needs antibiotics, stone fragments that stick on the way out, and the need for repeat treatment or a different treatment if a stone will not break. Less often, a severe infection can develop that needs intravenous antibiotics, sometimes with a small drain placed into the kidney.

Leaflets from different hospitals group these risks in slightly different ways and do not agree on exact frequencies, so ask your own team how they describe them. Bleeding around the kidney is rare but is why blood thinners are managed carefully.

Contact your hospital stone team, your GP or NHS 111 if you develop a fever, shivering, severe pain that painkillers do not control, increasing bleeding, or you cannot pass urine. Go to A&E or call 999 if you feel very unwell or faint with a high temperature.

Questions worth asking include how many sessions are usually needed for a stone like yours, what the plan is if it does not break, when the next scan will be, and what you can do to lower the chance of new stones. NHS and private hospitals use similar machines. Private care is more likely to offer a quicker date and one named surgeon, while price lists vary in whether the follow-up scan is included.