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Urinary Tract Obstruction
Introduction
Urinary Tract Obstruction can be the result of various pathological processes, intrinsic and
extrinsic to the renal system. Symptoms and signs of obstruction are often mild, occurring over
long periods of time and requires a high index of suspicion for diagnosis.
Def inition
Urinary Tract Obstruction is an interference with the flow of urine at any location along the
urinary tract. An obstruction may be anatomic or functional; it impedes flow proximal to the
blockage, dilates the urinary system, increases the risk for infection and compromises renal
function.
Caus e so f Urinary Tract Obstruction
The causes of Urinary Tract Obstruction can be grouped by the site at which the obstruction
occurs. Four examples of these causes are Calculi occurring within the lumen, Ureteric, Urethral
or ureterovesical stricture that occurs within the wall, Phimosis and tumors.
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Certain points along the urinary tract are more susceptible to obstruction and these include:
1. Pelvi- Ureteric junction (PUJ)
2. Where the ureters cross the pelvic brim, at the level of the iliac vessels.
3. Vesico -ureteric junction (VUJ)
Obstuction can be either unilateral or bilateral:
Unilateral- calculi and neuromuscular malfunction at the junction of the renal pelvis and
ureter are the most common causes of this form of obstruction.
Bilateral- In the developed world, 75% are due to prostate, calculi and bladder tumors.
R e nal Calculi are hard, small stones that form in the renal structures. Calculi are most
commonly made up of Calcium crystals. These Calculi may be found anywhere from the kidney
to the bladder. Their size may vary from minute granular deposits, called sand or gravel, to
bladder stones as large as an orange.
These stones may form when there is a deficiency of substances that normally prevent
crystallization in the urine, such as, citrate, magnesium, nephrocalcin and uropontin. The fluid
volume status also plays a role in the calculi formation in that the stones tend to occur more
often in dehydrated patients. Renal Calculi can also be caused by either increased urine pH (e.g.
calcium carbonate stones) or decreased urine pH (e.g. uric acid stones) Certain dietary habits or
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drugs can also result in stone formation also urine stasis (no movement) anywhere in the
urinary tract, increases the likelihood of stone formation.
Depending on where a stone forms, it may be called a kidney stone, ureteral stone, or bladder
stone. The process of stone formation is called urolithiasis, renal lithiasis, or nephrolithiasis.
Calculi formation is also influenced by three endogenenous factors;
(1) Crystal growth inhibiting factors. These are substances that are capable of minimizing
the risk of calcium phosphate or calcium oxate precipitation in the urine and ensuing
stone formation. These substances include pyrophosphate, potassium citrate and
magnesium.
(2) P article Retention. This occurs primarily at the papillary collecting ducts. Urinary stasis,
anatomic abnormalities or inflamed epithelium within the urinary tract prevents the
flushing of crystals from the system, escalating the possibility of the development of
calculi.
(3) Matrix . This is an organic material found in the urinary calculus. Some urinary calculus
contains significant amounts of organic matrix caused by tissue damage.
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Som e Common Signs and Symptoms
These includeinfection (pyelonephritis and cystitis with chills, fever and dysurea) can occur due
to constant irritation by the stones. Pain and renal colic; when the stone is lodged in the ureter,
it is common to have pain radiate down to the genetalia. The pain results when the stones
prevent the urine from draining. Other signs and symptoms include hematuria from irritation
done by the stone. Urinary Retention can occur if the stone obstructs the bladder neck. Some
clients may experience nausea, vomiting and diarrhea because of the proximity of the gastro
intestinal structures.
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M anag e m e nt o f R e nal Calculi
Renal Calculi are treated medically if possible. The basic goals of management include,
eradicating the stone, determining the stone type, to prevent nephron destruction, to control
infection and to relieve any obstruction that may be present. If possible fluids are encouraged;
this increases the hydrostatic pressure behind the stone, assisting it in its downward passage.
Intravenous fluids are administered to hydrate the client and help flush the stone out of the
body provided that the stones are 5mm or smaller because if they are larger the wont pass out.
To detect the passage of stones all urine passed out is strained and pain medication such as
morphine is given to relieve the pain Interventions are used when the client is unable to pass
the stones, infection has developed, impaired renal flow or continuous severe pain.
Lithotripsy is a form of therapy that is used to break the stones into smaller parts that can be
removed or urinated out. Blood in the urine is common after this procedure. Some clients
require surgery and the type of surgery to be performed depends on the location of the stone.
Endoscopic procedures or open surgery can be used. Endoscopic procedures for the bladder
include a cystoscopy for small stones and a cystolitholapaxy for larger stones. The open surgery
procedure would include a cystotomy for stones in the bladder and an ureterolithotomy for the
ureter. If the stone is very large, a nephrolithotomy (surgical incision into the kidney to remove
the stone) is performed.
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L ithotripsy
Cytoscopy
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D iagnostic Evaluation
The diagnosis of renal calculi can be made by the use of a kidney-ureter-bladder examination,
ultrasonography, intravenous urography,or retrograde pyelography.Intravenous
pyelogram.Blood chemistries and a 24-hour urine test for measurement of calcium, uric acid,
creatinine,sodium, pH, and total volume are part of the diagnostic workup.
Pr e disposing Factors o f Urinary tract Obstruction
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These factors would include, diet, medication, lifestyle factors and genetics. Obesity and weight
gain increase the possibility of kidney stones due to increased excretion of overabundant
calcium, oxalates (calcium stones, usually formed with oxalate, recurrently accompany
conditions that cause bone resorption, including immobilization and renal disease) and uric acid
(uric acid stones frequently accompany gout, a disease of increased uric acid production or
decreased excretion.)
Other factors include age in which Urinary Tract Infection occurs in the young (children not
those young at heart) and the old, in older men it is a relatively common condition due to
prostatic enlargement whilst in children it is due to congenital abnormalities such as
hydronephrosis( distension of the pelvis of the kidney).
Another factor is sex, in men urinary tract obstruction is most frequently a result of urethral
stricture whilst, in women, it tends to be associated with pelvic tumors (particularly
gynecological malignancies), prolapse of pelvic structures, or pregnancy.
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Tabl e o f Cont e nts
Introduction, Def inition and Caus e s f or UTO«.pg1
R e nal Calculi«pg2
Common Signs and symptoms o f R e nal Calculi...pg3
M anag e m e nt o f R e nal Calculi«pg. 4 & 5
D iagnostic Evaluations«pg6
Pr e disposing Factors o f R e nal Calculi«pg7