Stones in the urinary tract, called calculi, occur commonly in adults, but less often in children. Stone formation in children is more likely to be caused by an underlying metabolic disorder or anatomical abnormality.
Many children who form urinary stones have an abnormality of their urinary tract, including obstructions of the kidneys or ureters. Other causes may be complications of diseases, such as spina bifida and bladder exstrophy. These anatomical problems make the treatment of stones in children more complicated, so seeing a pediatric urologist is important to your child’s continued good health.
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What Is Pediatric Stone Disease?
Pediatric stone disease is the development of stones in the urinary tracts of children.
Urinary stones or calculi in the urinary tract may be composed of several different materials. Stones result from minerals and salts in high concentrations exceeding the saturation point and forming crystals. This crystallization can occur either because there is an abnormally high amount of stone-forming material in the urine or the urine is too concentrated because of dehydration (thirst).
The incidence of calcium stones in adults is high; the minority of adults who form stones do so because of a significantly abnormal amount of chemicals in the blood or urine.
In children, however, stone formation is less common and, therefore, more likely to be caused by an underlying metabolic or anatomical abnormality.
Many children who form urinary stones have underlying urinary tract abnormalities. These abnormalities include obstructions of the kidney or ureters, and diseases such as spina bifida and bladder exstrophy.
These anatomical problems make the treatment of stones in children more complicated and require that they be treated by a pediatric urologist.
What are the types of urinary tract stones?
Several materials form stones in the urinary tract, including:
- Calcium — Usually in the form of calcium oxalate, the most common type of stone in both children and adults.
- Cystine — Only in children and adults with hereditary cystinuria.
- Magnesium ammonium phosphate — Only in association with urinary infection.
- Uric acid —The same chemical that causes gout.
How common is pediatric stone disease?
Although bladder and kidney stones are common among adults, they are rare occurrences in children, although rates have been increasing over the past decades. Approximately 5 to 36 children per 100,000 are affected by pediatric stone disease.
What causes pediatric stone disease?
Calculi or urinary stones occur commonly in adults, but less often in children. Stone formation in children is more likely to be caused by an underlying metabolic or anatomical abnormality.
Pediatric stone disease risk factors
A risk factor is anything that puts a person at a greater chance of a medical issue.
Contributing risk factors for pediatric stone disease include:
- Dietary choices – Certain foods increase the chance of developing stones.
- Genetic predisposition – Having another family member with the disease.
- Underlying metabolic disorder – Can contribute to the development of stones.
Complications of pediatric stone disease
The main complication of untreated pediatric stone disease is chronic kidney disease.
How can I reduce my child’s risks of pediatric stone disease?
To reduce the risk of your child developing future kidney stones, it helps to learn what type of stones your child had. Then, you can make dietary changes to prevent the redevelopment of stones. A dietitian who specializes in kidney stone prevention can help you plan meals.
For example, if your child has calcium oxalate stones, they should avoid foods that produce high oxalates in the urine, such as tree nuts and tree nut products, peanuts, rhubarb, spinach, and wheat bran. Reducing sodium (salt) and limiting animal proteins (meat, eggs, dairy) may also help make a child less likely to develop oxalate kidney stones.
Calcium phosphate stones are more likely in children who eat higher amounts of sodium. Sodium is in many canned, fast, and packaged foods, as well as in many condiments, meats, and seasonings. Reducing sodium and limiting animal proteins are also helpful steps for preventing calcium phosphate stones.
Children with uric acid stones also can benefit from limiting animal proteins and can substitute legumes — such as beans, dried peas, lentils, and peanuts — as high-protein plant-based alternatives to animal products.
For children with cystine stones, drinking more liquids – especially water – is the biggest change they can make to prevent stone development. Your child's provider can tell you how much liquid your child needs per day based on their age, size, and activity level.
What Are the Signs and Symptoms of Pediatric Stone Disease?
Urinary stones may be found anywhere in the urinary tract.
Stones in the calyces – the cuplike structures inside the kidneys that collect urine before it flows into the larger renal pelvis – usually do not cause pain. Stones at the ureteropelvic junction or in the ureters can obstruct the kidneys intermittently or continuously, causing severe pain. Stones in the bladder may cause irritability with frequent urination and discomfort with urination.
Stones often form in bladders that have been enlarged with intestine; these usually cause no symptoms.
Symptoms of kidney stones in children include:
- A feeling of constant need to urinate.
- Cloudy or foul-smelling urine.
- Fever or chills.
- Hematuria – Presence of pink, red, or brown blood in the urine.
- Inability to urinate or ability to release only a tiny amount of urine.
- Irritability — Especially in young children.
- Nausea.
- Pain while urinating.
- Pain that may not last long or may last a long time and come and go in waves.
- Sharp pain in the back, lower belly, side, or groin.
- Vomiting.
When should I see a doctor about my child’s pediatric stone disease symptoms?
If your child has any of these symptoms, make an appointment with their primary care provider right away. These symptoms can be caused by kidney stones or a more serious condition.
How Do You Diagnose Pediatric Stone Disease?
Urinary stones are usually diagnosed in adults after they experience pain or see blood in their urine.
While these symptoms may occur in children, most often the stones are found on x-rays done for other reasons, or after vague and seemingly unrelated symptoms.
When a stone in a ureter causes severe pain, narcotic medication is usually given as treatment in the emergency room. Sometimes the pain will go away completely for days, or even weeks. That doesn’t mean that the stone is gone, and follow-up x-rays should always be done to be certain.
A stone left in the urinary tract for months or years because of a lack of symptoms can still cause severe kidney damage or even result in loss of the kidney. A stone in the ureter will often pass spontaneously.
Your doctor can tell by the size of the stone on the x-rays whether the stone is likely to spontaneously pass. If not, the stone will need to be treated in other ways.
How Do You Treat Pediatric Stone Disease?
Remarkable breakthroughs in urinary stone treatment have been made in the past 20 years. In the past, the only option for removing stones was an open operation. Now, open surgery is rarely performed for stone disease.
If open surgery is proposed for your child's stone disease, ask about less invasive treatments that might be available.
At UPMC, we offer noninvasive and minimally invasive procedures to treat pediatric stone disease:
Extracorporeal shock wave lithotripsy (ESWL)
The most cutting-edge treatment for urinary stones is extracorporeal shock wave lithotripsy (ESWL) — a noninvasive treatment that uses shock waves from outside the body to break up urinary stones inside the body. In this treatment, x-ray or ultrasound energy is used to focus shock waves on the stone, breaking it without damaging the body's normal tissues.
Is ESWL safe?
The safety of ESWL on the developing kidney has not been established beyond a doubt, but it seems from many large studies that this is a safe and effective way to treat pediatric kidney and ureteral stones.
Most children require some form of sedation to keep them calm and still during the procedure so that the focus on the stone can be maintained. The more powerful forms of ESWL can be painful; children require anesthesia for these forms.
Most kidney stones in children can be treated with ESWL.
Other treatments may be necessary due to:
- Previous failure by ESWL to fragment the stone.
- The child's anatomy, or previous reconstructive operations on the urinary tract.
- The size of the stone — Large stones may best be treated by removing the entire stone, rather than subjecting the kidney to multiple ESWL treatments and the possibility of obstruction due to a roadblock of stone fragments in the ureter.
Endoscopic approaches
In some situations, endoscopic approaches are most useful in treating urinary stones in children. Endoscopy refers to using telescopes inside the body. The urinary tract has long been approached using cystoscopes (bladder scopes), as well as nephroscopes (kidney scopes) and ureteroscopes (ureter scopes).
Urinary tract surgery using telescopes
The specialty of endourology refers to the use of telescopes to perform surgery within the urinary tract. The most common application of endourology involves the removal of urinary stones.
Kidney stones may be approached endoscopically in two ways:
- Ureteroscopically — through the bladder and ureter. The ureter of a child is much smaller than that of an adult and can be injured by surgical instruments, although the recent introduction of smaller flexible ureteroscopes has made access through the ureter feasible. It is more likely, however, that a percutaneous approach will be used for a large stone.
- Percutaneously — through the skin. The percutaneous removal of kidney stones (percutaneous nephrolithotomy, or PCNL) was developed for the removal of stones in adults and has been used in children, mostly without modification. A few medical centers have tried to downsize the instruments to make them more appropriately sized for children, but these efforts have been sporadic.
Mini-perc technique
Recently, UPMC pediatric urologists have developed a technique referred to as the "mini-perc," which was specifically designed for pediatric percutaneous nephrolithotomy (PCNL). With the assistance of Cook Urological, they have developed sheaths to accommodate the passage of miniature endoscopes (Circon/ACMI), which facilitate the removal of kidney and ureteral stones through small punctures.
The technique has been applied to many different stone types in children, who have ranged in size from 11 pounds up to adult weights. In most instances, an interventional radiologist will place a tube into the kidney the day before surgery. This percutaneous nephrostomy tube gives doctors access to the kidney.
Sometimes the specialists will skip this step and obtain access in the operating room. They first advance a guide wire into the kidney, and over this wire place a catheter (tube) that has two passages. The second passage is used to introduce a second safety wire. The catheter is then removed and the sheath is inserted.
Once the sheath is in place, the stone(s) are either removed whole or are fragmented (broken up) and removed. Stones can be broken using several forms of energy, including laser, ultrasonic, and electrohydraulic. Small rigid and flexible telescopes can be used to see all parts of the inside of the kidney and ureter.
Stones and fragments can be removed using miniature graspers and baskets passed through the scopes. UPMC pediatric urologists have used the mini-perc technique for years with success equal to standard forms of percutaneous stone removal. It is important to note that more than one procedure is often necessary to remove all stone fragments, and that a small nephrostomy tube is left in the kidney until the process is completed.
Surgery for bladder stones
Bladder stone surgery in the United States is most commonly associated with urinary tract reconstruction, either for bladder exstrophy or neurogenic bladder.
- Bladder exstrophy is a congenital condition in which the bladder protrudes outside the body.
- Neurogenic bladder results from damage to the nerves that control bladder function.
Stones also often form in people whose bladders have been enlarged or augmented.
Why Choose UPMC for Pediatric Stone Disease Care?
UPMC Children's Hospital of Pittsburgh is a multidisciplinary clinic that treats and manages pediatric stones.
A team of specialists, including a urologist with specialty training in the management of stone disease, a nephrologist, and a nutrition specialist, create a treatment plan and follow the patient's progress over the long term.
