is the use of high-energy shock waves to
fragment and disintegrate kidney stones.
The shock wave, created by using a high-voltage
spark or an electromagnetic impulse outside
of the body, is focused on the stone. The
shock wave shatters the stone, allowing
the fragments to pass through the urinary
system. Since the shock wave is generated
outside the body, the procedure is termed
extracorporeal shock wave lithotripsy (ESWL).
The name is derived from the roots of two
Greek words, litho, meaning stone, and trip,
meaning to break.
ESWL is used when a kidney stone is too
large to pass on its own, or when a stone
becomes stuck in a ureter (a tube that carries
urine from the kidney to the bladder) and
will not pass. Kidney stones are extremely
painful and can cause serious medical complications
if not removed.
For an unknown reason, the number of persons
in the United States developing kidney stones
has been increasing over the past 20 years.
White people are more prone to develop kidney
stones than are persons of color. Although
stones occur more frequently in men, the
number of women who develop them has been
increasing over the past 10 years, causing
the ratio to change. Kidney stones strike
most people between the ages of 20 and 40.
Once persons develop more than one stone,
they are more likely to develop others.
Lithotripsy is not required for treatment
in all cases of kidney stones.
Lithotripsy uses the technique of focused
shock waves to fragment a stone in the kidney
or the ureter. The affected person is placed
in a tub of water or in contact with a water-filled
cushion. A sophisticated machine called
Lithotripter produces the focused shock
waves. A high-voltage electrical discharge
is passed through a spark gap under water.
The shock waves thus produced are focused
on the stone inside the person's body. The
shock waves are created and focused on the
stone with the help of a machine called
C-Arm Image Intensifier. The wave shatters
and fragments the stone. The resulting debris,
called gravel, can then pass through the
remainder of the
ureter, through the bladder, and through
the urethra during urination. There is minimal
chance of damage to skin or internal organs
because biologic tissues are resilient,
not brittle, and because the shock waves
are not focused on them.
shock wave is characterized by a very rapid
pressure increase in the transmission medium
and is quite different from ultrasound.
The shock waves are transmitted through
a person's skin and pass harmlessly through
soft tissues. The shock wave passes through
the kidney and strikes the stone. At the
edge of the stone, energy is transferred
into the stone, causing small cracks to
form on the edge of the stone. The same
effect occurs when the shock wave exits
the stone. With successive shock waves,
the cracks open up. As more cracks form,
the size of the stone is reduced. Eventually,
the stone is reduced to small particles,
which are then flushed out of the kidneys
or ureter naturally during urination.
ESWL should not be considered for persons
with severe skeletal deformities, people
weighing more than 300 lb (136 kg), individuals
with abdominal aortic aneurysms, or persons
with uncontrollable bleeding disorders.
Women who are pregnant should not be treated
with ESWL. Individuals with cardiac pacemakers
should be evaluated by a cardiologist familiar
with ESWL. The cardiologist should be present
during the ESWL procedure in the event the
pacemaker needs to be overridden.Prior
to the lithotripsy procedure, a complete
physical examination is performed, followed
by tests to determine the number, location,
and size of the stone or stones. A test
called an intravenous pyelogram (IVP) is
used to locate the stones, which involves
injecting a dye into a vein in the arm.
This dye, which shows up on x ray, travels
through the bloodstream and is excreted
by the kidneys. The dye then flows down
the ureters and into the bladder. The dye
surrounds the stones. In this manner, x
rays are used to evaluate the stones and
the anatomy of the urinary system. Blood
tests are performed to determine if any
potential bleeding problems exist. For women
of childbearing age, a pregnancy test is
done to make sure they are not pregnant.
Older persons have an EKG test to make sure
that no potential heart problems exist.
Some individuals may have a stent placed
prior to the lithotripsy procedure. A stent
is a plastic tube placed in the ureter that
allows the passage of gravel and urine after
the ESWL procedure is completed.
process of lithotripsy generally takes about
one hour. During that time, up to 8,000
individual shock waves are administered.
Depending on a person's pain tolerance,
there may be some discomfort during the
treatment. Analgesics may be administered
to relieve this pain.
Most persons pass blood in their urine after
the ESWL procedure. This is normal and should
clear after several days to a week. Lots
of fluids should be taken to encourage the
flushing of any gravel remaining in the
urinary system. Treated persons should follow
up with a urologist in about two weeks to
make sure that everything is progressing
as planned. If a stent has been inserted,
it is normally removed at this time.
pain is fairly common after ESWL, but it
is usually not a cause for worry. However,
persistent or severe abdominal pain may
imply an unexpected internal injury. Occasionally,
stones may not be completely fragmented
during the first ESWL treatment and further
lithotripsy procedures may be required.
people are allergic to the dye material
used during an IVP, so it cannot be used.
For these people, focused sound waves, called
ultrasound, can be used to identify where
the stones are located.
blow for kidney stones
In most cases, stones are reduced to gravel
and passed within a few days. Individuals
may return to work whenever they feel able.
and mortality rates
Colicky renal pain is very common when gravel
is being passed. Other problems may include
perirenal hematomas (blood clots near the
kidneys) in 66% of the cases; nerve palsies;
pancreatitis (inflammation of the pancreas);
and obstruction by stone fragments. Death
is extremely rare and usually due to an
undiagnosed associated or underlying condition
that is aggravated by the lithotripsy procedure.
Before the advent of lithotripsy, surgery
was used to remove kidney stones. This approach
is uncommon today, but occasionally used
when other conditions prevent the use of
lithotripsy. Attempts are occasionally made
to change the pH of urine so as to dissolve
kidney stones. This treatment has limited
to "Urology Surgery"