ESWL Treatment for Kidney Stones

Kidney Stone Positioned on X-ray
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About 12 percent of all people will have kidney stones at some point in their lives. In fact, kidney stones are the third most common urological presentation behind urinary tract infections and prostate disease.

Kidney stones are exquisitely painful and result in back, flank or groin pain. The character of this pain is typically intermittent. Other symptoms that accompany kidney stones are fever, chills, nausea, vomiting, bloody urine and colored urine. In most people, the pain of a kidney stone compels a trip to the emergency room.

Stones can form in the bladder, ureters or kidney. When such stones are found in the kidney, they can also be referred to as renal calculi or nephrolithiasis. Kidney stones can either be obstructing or nonobstructing. Obstructing kidney stones are larger (greater than 7 mm) and clog up the urinary tract thus requiring aggressive treatment. Nonobstructive kidney stones are smaller and usually pass on their own and don't require a hospital stay. Instead, if you present to the emergency room with stones that will likely pass, you'll receive pain medications (NSAIDs with or without opioids) and instructions to hydrate and follow-up with your physician.

Kidney stones are usually composed of calcium oxalate. However, depending on their cause, the composition of kidney stones varies, and they can also be made of calcium phosphate, struvite, cystine or uric acid. When kidney stones pass into the urine, they can be detected as sediment which can aid in the diagnosis of this condition.

When a person presents to the emergency room with a suspected diagnosis of kidney stones, an abdominal CT without contrast is usually ordered to visualize any kidney stones. Kidney stones can also be visualized using other diagnostic modalities including ultrasound, x-ray, MRI, and fluoroscopy. Additionally, a urinalysis is also ordered to examine the urine for crystals and red blood cells (which indicate bleeding).

Particularly large kidney stones which obstruct the urinary tract may require surgery for removal. Surgery for kidney stones, however, is now rarely performed. Instead, extracorporeal shock wave lithotripsy (ESWL) has become the go-to procedure when treating kidney stones.

With ESWL, high-energy sound waves are used to shatter kidney stones which are visualized using ultrasound. These bits of kidney stone can then freely pass through the urinary tract via the urine. Interestingly, the technology used to develop ESWL is based on technology used to develop supersonic aircraft.

There are two ways that ESWL can be applied. First, ESWL can be applied by means of a water bath where you submerge in water and high-energy sound waves are sent through the water. Alternatively, these high-energy sound waves can be directed through a water cushion placed up against your skin. Both procedures can be uncomfortable and anesthesia is commonly administered during the procedure. Anesthesia also hastens recovery times after ESWL.

Even with the use of anesthesia, ESWL can still be painful. Specifically, ESWL is most painful when the density of the medium through which the sounds waves are traveling like between water and tissue or tissue and stones. Thus, the pain is commonly visceral, deep in the kidney where the stone is located.

Although ESWL is generally safe, rarely it can cause heart arrhythmias or mess with pacemakers. Additionally, ESWL can sometimes mess with blood pressure and exacerbate heart failure. Some degree of renal injury and bleeding is normal after use of ESWL.

In addition to surgery or ESWL, in certain situations, ureteroscopy and endoscopy can also be used to visualize and remove kidney stones. Ureteroscopy is used to recover stones caught in the ureters.

Kidney stones are due to the combined effects of genetics and environment. Depending on the cause, you can sometimes take certain steps to prevent kidney stones. For example, the most common risk factor associated with kidney stones is dehydration; thus, drinking plenty of water or even taking diuretics (water pills) can help prevent kidney stones. (Your physician should prescribe the diuretics.) Furthermore, certain foods can contribute to the development of certain types of kidney stones. For instance, spinach contains oxalate, a component of kidney stones composed of calcium oxalate. Furthermore, reducing the amount of meat and sodium that you eat can also prevent calcium oxalate kidney stones. 

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