What is a kidney stone?
Kidney stone = nephrolithiasis
Ureteral stone = ureteral lithiasis
Simply urolithiasis is a stone in the urinary tract. Sometimes they cause
symptoms such as pain (colic), hematuria (blood in urine), fevers, chills,
nausea and vomiting. Ureteral stone disease is among the most painful
and prevalent of urologic disorders. As many as 5 percent of Americans
will be affected by urinary stones at
some point in their lives.
How does the urinary tract work under normal conditions?
The kidneys act as a filter system for the blood. It cleans the blood while getting rid of the wastes. Urine is the
waste product. It flows from the kidney to the bladder through two small tubes called the ureters. The ureters are
tiny. The ureters dump the urine into the bladder in a rhythmic pattern. The bladder is able to expand and
acccomodate large volumes until it is convenient to urinate. When it is time to urinate, the bladder forces the urine
out through the urethra and out of the body.
What is a kidney stone?
Stones (urolithiasis) form in the kidney. A stone gets its name from where it is located in the body. Therefore, a
kidney stone (nephrolithiasis) is located in the kidney. Once it moves out of the kidney and moves into the ureter it
is called ureteral lithiasis. I usually tell patients that stones form the same way crystals form in a glass or water.
Lets say you mix a table spoon of salt into a glass of water. The individual molecules are in solution. Over time the
water evaporates and crystals form at the bottom of the glass. The molecules fall out of solution, a process called
precipitation. A stone is the molecules in your urine coming out of solution and forming a crystal.
What are the signs of a problem?
In general, a stone does not cause any symptoms unless it obstructs. When the stone moves from the kidney into
the ureter it goes into smaller openings or tight areas. The stone gets caught and prevents urine flow. The
pressure builds up behind the stone. This causes stretching of the ureter and thus causes pain. Think of it as
pluming in your house. If there is something blocking the pipes in the basement, the toilet upstairs will overflow.
The symptom of a kidney stone is extreme pain. Having been described as being worse than childbirth, the pain
often begins suddenly as the stone moves in the urinary tract, causing irritation and blockage. Typically, a person
feels a sharp, cramping pain in the back and in the side of the area of the kidney or in the lower abdomen, which
may spread to the groin. Also, sometimes a person will have blood in the urine, nausea and/or vomiting.
Occasionally, stones do not produce any symptoms. But while they may be "silent," they can be growing, even
threatening irreversible damage to kidney function. More commonly, however, if a stone is not large enough to
prompt major symptoms, it still can trigger a dull ache that is often confused with muscle or intestinal pain.
The size of stones is small. Some often wonder why something so small can cause so much pain. Remember it is
all relative to the size of the ureter. Statically, a person should be able to pass a stone 4mm or less. Stone larger
than 4mm have less of a chance to pass. Some people are able to pass stones 8mm in size, others
are unable to pass stones 2mm in size.
How are ureteral stones diagnosed?
Sometimes "silent" stones — those that cause no symptoms — are found on X-rays taken during a general health
exam. These stones would likely pass unnoticed. If they are large, then treatment should be offered. More often,
ureteral stones are found on a X-ray or sonogram taken on someone who complains of blood in the urine or
sudden pain. These diagnostic images give the doctor valuable information about the stone's size and location.
Blood and urine tests also help detect any abnormal substance that might promote stone formation.
If your doctor suspects a stone but is unable to make a diagnosis from a simple X- ray, he/she may scan the
urinary system with CT scan. Completing a CT scan is fast and painless. No needles are needed.
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