Urinary stones, which are called calculi, are often found in adults. Increasingly, children and adolescents suffer from them as well.
Calculi form because there is too much of the ingredients of the stone, and not enough water in the urine. This 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).
Materials that form stones include:
- Calcium
- Uric acid
- Cysteine
- Magnesium ammonium phosphate
Many children who form urinary stones have an underlying abnormality of the urinary tract. These include obstructions of the kidney or ureter, and diseases such as spina bifida and bladder exstrophy. These anatomical problems make the treatment of stones in children more complicated and require that any treatment be given in conjunction with a pediatric urologist.
Most pediatric stone disease can be treated in an effective and durable manner using endoscopic techniques. With endoscopic techniques, large incisions to remove stones are unnecessary.
Surgical Options
Ureteroscopy with laser lithotripsy for smaller stones (1mm –15 mm)
The ureter is the tube that connects the kidney to the bladder. Stones that lodge in the ureter may be treated with a urtereoscope. The ureteroscope is a rigid and flexible small caliber scope that allows the ureter to be explored. Through the working channel of the ureteroscope, the stone may be identified and treated with a laser lithoriptor that fragments the stone to sand and small pieces. Small instruments such as flexible baskets are also used to grab and remove stone fragments from the ureter. Very often after a ureteroscopy a temporary internal drainage tube called a stent is left in place for some time. This allows the ureter to heal after a ureteroscopy. The stent is removed with a cystoscope at a later time.
Percutaneous nephrolithotomy (PCNL) for larger stones (>1.5 mm)
Larger stones may form within the kidney. These stones are often in the renal pelvis or calices of kidney; these are the inner tubes or urine collecting spaces. When stones form within these area they may be larger. Larger stones may often be treated effectively by a PCNL. With this procedure a small (1cm) incision is made on the skin of the back and a tract is created into the kidney. Through this tract larger stones can be broken up and removed efficiently. An Ultrasonic lithotripter may be used with this technique to pulverize the stone. After a PCNL a temporary drainage tube (nephrostomy tube) is left to drain the kidney to allow it to heal.
Percutaneous cystolithotomy to treat bladder stones
Some children are at increased risk to develop bladder stones. Depending on the size or location of these stones, minimally invasive techniques exist to address them. For larger stones a 1 cm incision is made on the skin overlying the bladder. A tract is developed into the bladder to facilitate effective stone fragmentation and removal. For smaller stones, a percutaneous approach may not be required. Smaller stones are most often addressed by placing a cystoscope into the bladder via the urethra (the tube one urinates out of) . Through this scope, bladder stones may be identified, fragmented, and removed.
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