Shock Wave Lithotripsy (SWL)

This card describes shock wave lithotripsy (SWL), also called extracorporeal shock wave lithotripsy or ESWL. It is the one option in the stone procedures drawer that works from outside the body, so it is included for comparison with ureteroscopy and percutaneous nephrolithotomy. It is general education only, and the treating urologist decides what suits a given stone.

What it is

MedlinePlus defines lithotripsy as a procedure that uses shock waves to break up stones in the kidney and parts of the ureter, after which the tiny pieces pass out in the urine. "Extracorporeal" means outside the body, and ESWL is the most common type of lithotripsy. Cleveland Clinic calls ESWL a common, nonsurgical procedure that uses high-energy pressure waves. See the glossary for lithotripsy and related terms.

Unlike laser lithotripsy, no instrument is passed into the urinary tract to deliver the energy. The shock waves travel through water and the body to the stone.

Why it is done

MedlinePlus says lithotripsy is used for kidney stones that cause bleeding, kidney damage, pain or urinary tract infections, and adds that not all stones can be treated this way. Cleveland Clinic says providers often use ESWL for stones larger than 5 millimeters that block urine flow or cause pain. It lists the factors that guide the choice as stone size (ESWL usually works best for smaller stones), stone location, the person's health conditions and medicines, and body type, since anatomy can put extra distance between the stone and the shock waves.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists SWL among the treatments a urologist may use, and the NHS describes it as a procedure for larger stones that is done without an anesthetic, so the person is awake.

How it is done, in outline

MedlinePlus says the person lies on an exam table on a soft, water-filled cushion, receives medicine for pain or relaxation and antibiotics, and may be given general anesthesia. High-energy shock waves, guided by x-ray or ultrasound, pass through the body until they reach the stone. Cleveland Clinic says a person may be asleep, awake but drowsy, or numb from the waist down with regional anesthesia, and that those who are awake may hear a popping sound or feel a popping sound or tapping on the side. The procedure takes about 45 minutes to 1 hour (MedlinePlus) or about an hour (Cleveland Clinic). NIDDK describes it as an outpatient procedure.

A stent may be placed before or after treatment to drain urine from the kidney until the pieces have passed (MedlinePlus).

Cleveland Clinic notes that people who have SWL without anesthesia mostly report mild to moderate pain, while about 30% report severe pain during treatment.

Recovery

MedlinePlus says people stay in the recovery room for up to about 2 hours, and most go home the same day with a urine strainer to catch pieces of stone. Cleveland Clinic says most people return to usual routines within a few days. Soreness, slight bruising on the side, pink-tinged urine and painful urination are common and usually fade after a few days. Stone fragments, which may look like sand, gravel or dust, can keep passing for several days to weeks, and the pain may come and go as they move. A provider may prescribe tamsulosin or a pain reliever. Drinking plenty of water helps fragments move, and the stone pieces may be tested to help guide prevention.

Cleveland Clinic advises going to the emergency room for sudden severe belly or back pain, persistent nausea or vomiting, dizziness or lightheadedness, pain that worsens despite medicine, fever or chills, or blood clots in the urine.

Risks

MedlinePlus says lithotripsy is safe most of the time, and lists bleeding around the kidney that may need a blood transfusion, kidney infection, stone pieces blocking urine flow, pieces left behind that may need more treatment, ulcers in the stomach or small intestine, and kidney function problems. Cleveland Clinic summarizes the main risks as ureter blockage, bleeding and infection.

Effectiveness varies. Cleveland Clinic reports success rates from 30% to 90% depending on stone size, location and type, and body type. If SWL does not break the stone enough, a repeat SWL or ureteroscopy may follow.

Cleveland Clinic says a provider may recommend against SWL during pregnancy or with certain conditions, among them an abdominal aortic aneurysm, bleeding disorders, the need for blood thinners, obesity, a kidney or urinary infection, kidney cancer, reduced kidney function, spinal deformities and blood pressure that medication does not control.

Questions to ask your clinician

• Is my stone's size and location suited to shock wave lithotripsy?
• Will I be awake, sedated or under general anesthesia?
• Do any of my health conditions or medicines change whether SWL is appropriate?
• Will a stent be placed before or after treatment?
• How long might it take to pass the fragments, and how should I manage pain?
• What is the chance that I will need a second treatment or a different procedure?
• Which symptoms should make me contact you or go to an emergency room?