Kidney stones are made up of millions of tiny crystals that form when there is an imbalance in water, minerals and salts. Most kidney stones form on the interior surface of the kidney where urine leaves the kidney tissue and enters the urinary collecting system. Kidney stones can be small like a grain of sand but are often much larger.

• Calcium stones: The most common kidney stones are composed of calcium and oxalate while others are composed of calcium and phosphate. The stones can form due to a variety of reasons discussed below. Some of those who form calcium containing stones have too much calcium in their urine, a condition known as hypercalciuria which can occur three main ways. Some people absorb too much calcium from their intestines.
• Uric acid stones: Uric acid is produced from the metabolism of protein. When urine is too acidic urine becomes saturated with uric acid crystals.
• Struvite stones: These stones are composed of a mixture of magnesium, ammonium, phosphate and calcium carbonate. These stones form due to persistent or recurrent urinary tract infection with certain types of bacteria that can produce ammonia.
• Cystine stones: Cystine stones are rare, and they form only in persons with an inherited metabolic disorder that causes high levels of cystine in the urine, a condition known as cystinuria.

Most people are diagnosed with kidney stones due to pain which can sometimes be excruciating though it will often wax and wane while others may have more mild pain. Severe pain typically occurs when the kidney stone breaks loose and falls into the ureter, the tube that runs from the kidney to the bladder. Stones can block the drainage of urine from the kidney, a condition known as renal colic. The pain may begin in the lower back and may move to the side or even to the groin. Other symptoms may include blood in the urine (hematuria), frequent or persistent urinary tract infections, urinary urgency or frequency and nausea or vomiting.

People form kidney stones for various reasons, anytime there is an imbalance of minerals, salts and water in the urine. Dehydration, high salt intake, high non-dairy animal protein intake and a diet without sufficient fruits and vegetables are the most common contributors to kidney stone formation. However, there are many other factors, and these dietary considerations may not be the specific reason for an individual’s development of kidney stones.

If you have had one kidney stone, you are likely to form another. To reduce your chances of forming another stone, the first step is to determine why your original stone formed in the first place. At the USF Kidney Stone Center of Excellence, our Kidney Stone Prevention Program emphasizes an individualized, patient centered approach to stone prevention. This includes a thorough metabolic evaluation so that therapies can be appropriately directed towards the patient-specific metabolic issues.

When a kidney stone causes uncontrolled pain, severe nausea or vomiting or is associated with a solitary kidney, poor kidney function or severe blockage of the kidney, the stone should be treated. Obstructing stones associated with infection or fever can be life threatening and demand immediate decompression with either a nephrostomy tube or ureteral stent.

When a kidney stone causes uncontrolled pain, severe nausea or vomiting or is associated with a solitary kidney, poor kidney function or severe blockage of the kidney, the stone should be treated urgently. Obstructing stones associated with infection or fever can be life threatening and demand immediate decompression with either a nephrostomy tube or ureteral stent.

With small stones in the ureter, it may be appropriate give the stone a few weeks to pass on its own. Ureteral stones larger than 5 mm are less likely to pass spontaneously and should be considered for treatment. A trial of spontaneous passage is typically limited to 6 weeks or less to avoid kidney damage.

Small kidney stones (less than 5 mm) not causing any pain are often observed as there is a good chance these stones will pass spontaneously when they fall] into the ureter. However, there are a number of reasons to treat a kidney stone even if it is not causing pain. Some kidney stones may be infected, and in many cases, despite proper antibiotic treatment, the infection cannot be cleared from the stone. In such cases, the only way to eradicate the infection completely is to remove the stone. Staghorn stones are extremely large stones that grow to fill the inside of the kidney. There are serious health risks associated with these stones and left untreated they are associated with an increased risk of kidney failure. There are also additional situations in which even small stones should be treated. For example, the Federal Aviation Administration (FAA) will not allow a pilot to fly until all stones have been cleared from his or her kidney. A few other occupations also do not allow for the unplanned passage of a kidney stone. Likewise, frequent travelers, whether for business or otherwise, especially to places where medical care is not reliable, should consider treatment. Others may choose to remove their stones at a time when it is convenient for them in order to avoid the unpredictable future passage.

Shock wave lithotripsy (SWL) is a noninvasive procedure used to treat kidney stones that are too large to pass through the urinary tract. SWL treats kidney stones by sending focused ultrasonic energy or shock waves directly to the stone first located with fluoroscopy (a type of X-ray) or ultrasound (high frequency sound waves). The shock waves break a large stone into smaller stones that will pass through the urinary system. SWL allows persons with certain types of stones in the urinary system to avoid an invasive surgical procedure for stone removal.

The introduction of shock wave lithotripsy in the early 1980s revolutionized the treatment of patients with kidney stone disease. Patients who once required major surgery to remove their stones could be treated without an incision. SWL is the only non-invasive treatment for kidney stones, meaning no incision or internal manipulation is performed. Shock wave lithotripsy involves the administration of a series of shock waves to the targeted stone. The shock waves, which are generated by a machine called a lithotripter, are focused by x-ray onto the kidney stone. The shock waves travel into the body, through skin and tissue, reaching the stone where they break it into small fragments. For several weeks following treatment, those small fragments are passed out of the body in the urine.

In the decades since lithotripsy was first performed in the United States, we have learned a great deal about how different patients respond to this technology. It turns out that we can identify some patients who will be unlikely to experience a successful outcome following lithotripsy, whereas we may predict that other patients will be more likely to clear their stones. Although many of these parameters are beyond anyone's control, such as the stone size and location in the kidney, patient selection and physician experience can positively influence the outcome of the procedure.

Ureteroscopy is a procedure to address kidney and ureteral stones, and involves the passage of a small telescope, called a ureteroscope, through the urethra and bladder and up the ureter to the point where the stone is located. Ureteroscopy is typically performed under general anesthesia, and the procedure usually lasts from one to three hours. If the stone is small, it may be snared with a basket device and removed whole from the ureter. If the stone is large, or if the diameter of the ureter is narrow, the stone will need to be fragmented, which is usually accomplished with a laser. Once the stone is broken into tiny pieces, these pieces are removed.

The passage of the ureteroscope may result in swelling in the ureter. Therefore, it may be necessary to temporarily leave a small tube, called a ureteral stent, inside the ureter temporarily to ensure that the kidney drains urine well. If a stent is placed, follow up for stent removal is critical.

Ureteroscopy usually can be performed as an outpatient procedure, however; patients may require an overnight hospital stay if the procedure proves lengthy or difficult.

Ureteroscopy can treat stones located at any position in the ureter and kidney. Additionally, ureteroscopy allows the treatment of stones that cannot be seen on an x-ray. Certain patients who cannot be treated with ESWL or PERC, such as those who cannot safely stop taking blood thinners, women who are pregnant, and the morbidly obese, can be treated by ureteroscopy.

Ureteroscopy is not a particularly good treatment for:

• Patients with large stones: Ureteroscopy requires actively removing all stone fragments. The treatment of very large stones may yield so many fragments that complete removal becomes impractical or impossible.
• Patients with a history of urinary tract reconstruction: The anatomy of patients who have undergone ureteral or bladder reconstruction may not allow the passage of a ureteroscope.

PCNL is a technique used to remove certain stones in the kidney or upper ureter (the tube that drains urine from the kidney to the bladder) that are too large for other forms of stone treatment such as shock wave lithotripsy or ureteroscopy.

This procedure is accepted as the standard of care for patients with kidney stones that are large, very firm, or resistant to other forms of stone treatment. It has replaced open operations for kidney stones in the vast majority of patients. Typically, the length of the surgery is three to four hours. The surgery is performed by making a small 1 cm incision in the patient’s flank area. A tube is placed through the incision into the kidney under x-ray guidance. A small telescope is then passed through the tube in order to visualize the stone, break it up and remove it from the body. If necessary a laser or other device called a lithotripter may be used to break up the stone before it can be removed. This procedure has resulted in significantly less post-operative pain, a shorter hospital stay, and earlier return to work and daily activities when compared to open stone surgery.

This technique also has a higher success rate for clearing all stones in one setting than other techniques such as extracorporeal shock wave lithotripsy (ESWL), which often require several attempts. Although this procedure has proven to be very safe, as in any surgical procedure there are risks and potential complications. The safety and complication rates are similar when compared to the open surgery.

• Bleeding: Some blood loss will occur with this procedure but rarely do patients require a blood transfusion. Patients are typically monitored overnight to track the blood loss.
• Infection: All patients are treated with broad-spectrum antibiotics to decrease the chance of infection from occurring after surgery. If you develop any signs or symptoms of infection after the surgery (fever, drainage from incision, urinary frequency or discomfort, pain or anything that you may be concerned about) please contact us at once.
• Tissue / Organ Injury: Although uncommon, possible injury to surrounding tissue/organs including bowel, vascular structures, spleen, liver, lung, pancreas and gallbladder could require further surgery. Loss of kidney function is rare but is a potential risk. Scar tissue may also form in the kidney or ureter requiring further surgery.
• Failure to Remove the Stone: There is a possibility that the stone(s) may not be able to be removed completely, usually either due to the size or location of the stone(s). Additional treatment may be required.