Urinary Tract Obstruction
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Introduction
Obstruction to urine flow can occur at any point from the renal pelvis to the end of the urethra.
Unilateral ureteral obstruction usually does not cause any change in urinary flow or total renal function. Renal failure due to unknown causes, especially without proteinuria, should raise suspicion of obstruction.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
Causes of urinary tract obstruction include:
intraluminal obstruction
extrinsic compression
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acquired problems
congenital urinary tract malformations
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Pathophysiology
Signs and Symptoms
- history
- physical exam
History
A change in urinary habits is often the presenting sign of obstruction, with anuria often occurring. However, polyuria, especially nocturia, can also occur, likely due to defective urinary concentration.
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Azotemia or renal failure only occurs if drainage of both kidneys is significantly compromised, and total obstruction is an important cause of end stage renal disease.
Diagnostic Imaging
Renal ultrasound is quite useful.
Differential Diagnosis
Treatments
Management primarily involves identifying the site and cause of the obstruction, with relief usually involving surgery.
For fetal obstruction, treatment is usually delayed until after birth. Surgically, a shunt can be made between the bladder and the amniotic sac if necessary intrapartum.
Consequences and Course
Kidney failure can result due to dysplasia from increased pressure. GFR is decreased. Increased pressure leads to ANG II.
Ischemia can result from vasoconstriction, and atrophy is a final result.
Resources and References
Topic Development
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