Urinary Tract Stone Disease

Chemical ions, molecules, and compounds normally exist in urine (i.e., calcium, oxalate, phosphate, uric acid). When the concentrations of these substances are high, they combine to form crystals. Under appropriate environmental conditions and with the aid of debris in the urinary tract, these crystals will grow and aggregate together resulting in the formation of larger crystals and eventually stones.

Who is most likely to get stones?

Anyone can develop a urinary tract stone. However, Caucasian men in their twenties to forties are more likely to get stones than other individuals.

Other risk factors for stone development include:

• Living in mountainous, desert, or tropical areas

• Having family members with stones

• Coming from a certain ethnic background (i.e., European)

• Consuming a certain diet

• Having a sedentary occupation.

Additionally, stones may be more common during summer months.

What types of stones exist?

Stones can grow assuming various shapes and sizes (see photographs). Very large stones are sometimes called staghorn stones. Depending upon their size and number, stones can be located in a kidney calyx, renal pelvis, ureter, or urinary bladder. Size and location help to classify stones and help to determine treatment when necessary.

Crystalline composition is also essential to stone classification. When the crystalline composition of a stone is known, it helps guide dietary, medical, and surgical therapy for the stone. Different crystalline stone types are calcium oxalate, calcium phosphate, uric acid, magnesium ammonium phosphate, and cystine stones.

What symptoms do stones cause?

Some stones may not cause any symptoms at all. However, others may be associated with lower back, abdominal, or groin pain, blood with urination, nausea, vomiting, fever and/or impaired kidney function.

What treatments exist for stones?

Observation – Smaller stones (approximately 5 mm in size or less) can be followed and given an opportunity to pass spontaneously.

SWL – Shock wave lithotripsy utilizes shock wave energy traveling through water to fragment a stone. The stone fragments are then allowed to pass independently or are retrieved with endoscopic measures.

Endoscopic Procedures – These procedures use minimally invasive technology to localize a stone, fragment it with an energy source when necessary (i.e., laser), and then retrieve the fragments. Endoscopes with magnifying cameras are advanced into the drainage system of the urinary tract in order to facilitate stone fragmentation and retrieval (see picture).

Other Surgical Procedures – Rarely, it is necessary to utilize laparoscopic/robotic or traditional open surgery in order to treat urinary tract stone disease.

Medical Therapy – Certain stones can be treated with medications in order to help them dissolve. In particular, uric acid and cystine stones may be treated by a process known as alkalinization of the urine. Additionally, fluid consumption, dietary intake, and medications can be used to prevent stone recurrences in patients who are likely to form stones.

What is a ureteral stent?

A ureteral stent is essentially a tube constructed from one of several biomaterials that provides constant drainage of urine from the kidney. A stent may be temporarily placed to help a stone pass or after some type of treatment has been performed for a stone.

This video illustrates the combination of endoscopic surgery (i.e., ureteroscopy) and shock wave lithotripsy to treat a kidney stone. The stone is visualized with endoscopic surgery. An attempt is made to displace the stone with a basket device. Shock wave lithotripsy is then used to fragment the stone into pieces.