Extracorporeal Shock Wave Lithotripsy (ESWL)

ESWL is the most common form of lithotripsy. Lithotripsy is a procedure that uses energy from shock waves to fragment stones in kidneys and ureters.

ESWL is a non-surgical procedure to treat stones, which means that it requires no skin cuts or invasive instruments. During this procedure, high-energy shock waves are generated by a machine outside the body (extracorporeal) and focused onto the stone. These waves travel through the body to break the stone into small grainy fragments. These fragments, due to their small size, are then passed through the urine.

Stones in the kidney are formed as a result of high levels of minerals and salts in urine. These include calcium, uric acid, magnesium ammonium phosphate and cystine stones. 

Sometimes, these stones travel down the urinary tract and pass out through the urine. However, if the stone gets stuck in the ureter, it can block the urine flow and cause pain.

Read more: Kidney stone analysis

The causes and risk factors of kidney stones include:

• Low urine volume due to dehydration, less fluid consumption or living or working in hot places. 
• A history of kidney stones in your family. 
• Obesity 
• Conditions that cause diarrhoea (e.g., ulcerative colitis) or certain surgeries (e.g., gastric bypass surgery) can increase your risk of kidney stones formed from calcium oxalate. 
• Your diet can also influence the formation of kidney stones. For example, a high animal protein diet obtained from fish, chicken or pork can increase the acid level in the urine, which increases the risk of kidney stones formed from calcium oxalate or uric acid.
• Certain medical conditions can increase the risk of kidney stone. For example, abnormalities of the parathyroid gland can affect the breakdown of calcium in the body and lead to kidney stones formed from calcium.

Typically, a kidney stone may show the following symptoms:

• Sharp pain and cramping in the back and side (flanks)
• An intense need to urinate
• Urinating often 
• Burning sensation during urination 
• Nausea and vomiting 
• In men, pain at the tip of the penis
• Dark or red urine 

Your healthcare practitioner may recommend ESWL if you have kidney stones that cause the following symptoms:

• Bleeding 
• Kidney damage 
• Pain 
• Urinary tract infections

Your doctor may recommend ESWL for the following types of kidney stones:

• Small kidney stones (usually less than 1 cm) that are easily seen on x-ray 
• Certain stones in the upper part of the ureter 

ESWL is avoided in the following conditions:

• Stones located lower down in the ureter 
• For immediate or complete clearance of stone
• Pregnancy 
• Active urinary tract infection 
• Obstruction of the kidney 
• Obstruction or presence of scar tissue in the ureter that prevents the passing of stone fragments 
• Use of blood-thinning medications that cannot be discontinued 
• Stones that are made of calcium phosphate or cystine

Before the surgery:

• Submit all the kidney-related reports including X-ray films, CT scan, MRI, sonogram or intravenous pyelogram (IVP) to your doctor.
• Inform your healthcare practitioner:
  • If you are or could be pregnant
  • The list of medicines that you are taking, including herbs, supplements and non-prescribed medicines
  • It is important to have infection-free urine before the procedure. Therefore, it is necessary to notify your healthcare practitioner if you have symptoms urinary tract infection (UTI) such as burning sensation on urination, blood in urine, fever and intense urge to urinate or frequent urination
• Your healthcare practitioner will ask you to stop blood-thinning medications and any other medicines that prevent blood clots for at least seven to 10 days. These include aspirin, ibuprofen, Vitamin E or warfarin.
• Based on your age, medication, history and overall health, your healthcare practitioner may order the following tests: 
  • Complete blood count
  • Electrocardiogram
  • Urine culture
  • Urinalysis
  • Comprehensive metabolic panel 
  • Blood coagulation profile

On the day of the surgery:

• Fasting for several hours may be required. 
• The doctor may give you some medicines that you can take with a sip of water.

For a majority of people, ESWL is an outpatient procedure, with no hospital admission.

The following steps are performed for this procedure:

• You will have to wear a hospital gown for this procedure.
• You will be asked to lie on a soft, water-filled cushion or will be placed in a tub with lukewarm water for the procedure.
• Before the procedure begins, you will be given antibiotics and medications to help you relax. 
• Your doctor will administer general anaesthesia or sedatives through a vein and then use an X-ray machine to pinpoint the location of the stones in the kidney. 
• High-energy shock waves will then be passed through your body to break the stones into small fragments. 
• After this, a stent (tube) will be placed into your kidney through your back or bladder. This will drain the urine and remove stone fragments from your body. 

ESWL takes approximately 45 minutes to one hour.

After the procedure:

• You will be kept in a recovery room for up to two hours and may be allowed to go home on the same day.
• A strainer will be given to you to collect the residual stone fragments that will pass through your urine.
• You may have a dull ache or soreness over the kidney or flank area. The pain is usually worst in the evening after the procedure and lessens over the following days. 
• You may have blood in urine for a few days to a couple of weeks after the procedure, which is normal. 
• A low-grade fever may occur though it is rare.

Usually, you can resume all daily activities within one or two days after the procedure. No special diet is required after this surgery. However, make sure to drink plenty of water to help the fragments pass out of your body. 

Oral pain medications and water can help relieve the pain that occurs when the fragments pass.

If you have blood in urine, keep up your fluid intake, avoid strenuous activities and don't take blood-thinning medications (ask your doctor before stopping any medication).

When to see the doctor?

You should immediately contact your healthcare practitioner if you have:

• Worsening of pain 
• Presence of a large number of blood clots in the urine that causes difficulty in emptying the bladder 
• Chest pain or difficulty in breathing 
• Fever more than 101°F
• Nausea and vomiting

Risks of ESWL procedure include:

• Bleeding and transfusion: Minor bleeding may occur following ESWL, which may be visible in the urine. Rarely, blood transfusion may be required if bleeding occurs in or around the kidney. 
• Adjacent tissue or organ injury: Rarely, injury to the surrounding skin, nerves, tissue, muscles and organs may occur. 
• Infection: Although antibiotics are given prior to surgery, infections within the urinary system can occasionally occur.
• Ulcers: Some people may get ulcers in the stomach or small intestine after the surgery. Read more: Stomach ulcer symptoms
• Ineffective or incomplete stone fragmentation: The success of ESWL depends on the size and composition of the stone, its location, the function of the affected kidney and the medical condition of the person. Hence, for some stones, multiple ESWL procedures may be required for adequate fragmentation. Also, some stones may not respond to ESWL despite multiple attempts.
• Impaired kidney function: There may be problems with kidney function after ESWL. 
• Accumulation of stone fragments: Pieces of the stone may block the urine flow from the kidney, causing pain and kidney damage. In such cases, additional procedures may be warranted.
• Shattered stone fragments: Shattered stone fragments may cause pain and distress when they pass through the urinary tract.

You may have a follow-up after several weeks, at which time your healthcare practitioner will perform an x-ray to determine if the stone has broken into fragments and if those small fragments have passed out of the kidney. If the fragments have not cleared, the doctor may repeat the X-ray after another couple of weeks. If the stone has not broken into fragments, repeat ESWL or other treatments such as ureteroscopy may be recommended.

Disclaimer: The above information is provided purely from an educational point of view and is in no way a substitute for medical advice by a qualified doctor.