Stones may cause problems anywhere in the urinary tract, from the kidney to the ureter and into the bladder. Most of the time, stones are found in the kidney or ureter.

In children, stone disease is less common than it is in adults. Some children who form urinary stones have an underlying abnormality or the urinary tract. These can include obstructions of the kidney and ureter, or diseases such as spina bifida. Many other children with stones have normal urinary tract anatomy.

At other times, however, it is necessary to remove the stones; this decision is based on the child's condition and symptoms. It also may be appropriate to remove a stone that is growing so that it may be removed more easily, rather than waiting until it is very large.

The usual methods to remove a kidney stone in children include extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), ureteroscopy, or open stone surgery. The choice of technique depends upon the location, size and type of stone, as well as the child's medical condition and anatomy. All methods are possible in children.

URETEROSCOPY

This is a technique that uses a small scope passed up through the urethra into the child's bladder, and from there up into one or both ureters and kidneys. The stone can be seen using digital cameras attached to the scope, and the stone can be removed with a variety of special instruments designed to capture the stone. In other cases, a laser fiber is passed through the scope and the stone is fragmented into many tiny pieces.

Ureteroscopy is done under general anesthesia. Sometimes after ureteroscopy, a small flexible tube called a stent is left in the ureter to allow urine to drain from the kidney into the bladder. This stent may also help the stone fragments pass. Stents may be removed after a few days or weeks, either in the operating room or in the clinic.

The success rate of ureteroscopy is very high, upwards of 95%. Success rates are lower for large stones which may require multiple treatments, and for systems with difficult anatomy that makes it difficult to get the scope up to the stone.

PCNL

Percutaneous nephrolithotomy (PCNL) is a technique in which a needle is used to puncture the kidney under ultrasound or X-ray guidance and an instrument is passed into the kidney to allow direct examination, fragmentation and removal of a stone. This technique requires the patient to be completely asleep. A kidney drainage tube is usually left in place for 2 to 4 days.

PCNL is particularly useful in a patient with a hard stone that might not fragment with ESWL or in whom the anatomy of the kidney is not normal. In those children, fragmented stones may not pass effectively. If a stone has created a serious obstruction, a kidney drainage tube (nephrostomy) may have already been placed and this may be used to remove the stone. Stones may be removed using this technique all the way to the bladder.

In small children, the size of the tube used for access to the kidney must be adapted to the child's size. A special, small percutaneous access sheath has been developed here to permit access to the kidney for stone removal in small children. This system is very useful for small and moderate stones, but less so for large stones (>2.0 cm). Other techniques used involve obtaining access with a variety of methods. Most involve some sort of kidney puncture and dilation of the tract to permit endoscopic treatment.

The metabolic evaluation includes:

• detailed medical history
• review of current prescribed and over the counter medications
• detailed diet and fluid intake history
• physical exam

• Analysis of urine - to assess for factors that contribute to stone formation, such as increased levels of calcium in the urine

• Blood tests - to look for other risk factors

• Chemical analysis of the stone (once it is passed or removed) - to identify the type of stone. This can provide important clues about why it formed.

• Evaluation for inherited disorders - to look at risk factors. Several rare inherited disorders can lead to kidney stones.

Treatment plan
All patients are prescribed high fluid intake and a low-salt diet to reduce kidney stone recurrence. The nephrologist may prescribe medications to help reduce the formation of kidney stones. Specific treatment will be created for patients who are found to have an inherited disorder that leads to kidney stones.

Addressing high levels of calcium in the urine
The most common kidney stone is caused by too much calcium in the urine. This is often seen in families with multiple members with kidney stones. Medication can be prescribed which lowers the levels of calcium in the urine, helps calcium-forming crystals dissolve better in the urine.