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Obstructive Uropathy

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Ismail Munir

Overview

Obstructive uropathy is a condition that affects the urinary system. It is characterized by an obstruction or blockage (either partial or complete) in the urinary tract that prevents urine from flowing from the kidneys to the bladder.&nbsp;Obstructive uropathy can affect any part of the urinary system, including the kidneys, ureters, bladder, and urethra such that the blockage prevents the urine from flowing freely. This can occur at any point along the urinary tract. 
&nbsp;

The kidneys are responsible for producing urine by filtering waste products and excess fluids from the blood after which the urine travels down the ureters &ndash; two thin tubes that connect the kidneys to the bladder.&nbsp;

As the urine backs up behind the obstruction, it creates pressure on the kidneys and can lead to swelling and damage to the renal tubules. The obstruction can also cause a decrease in urine output, which can lead to a buildup of waste products in the blood.

The incidence and prevalence of obstructive uropathy depend on various factors such as age, gender, underlying medical conditions, and environmental factors.

Obstructive uropathy is more commonly seen in males than females. Besides, the incidence of obstructive uropathy increases with age, with the highest incidence reported in patients over the age of 60. 
&nbsp;

Obstructive uropathy is classified according to the site, degree, and duration of the obstruction<a href="#accordion">[22]</a>:

<ul>
	<li>Acute Obstruction &ndash; changes are usually functional</li>
	<li>Chronic Obstruction &ndash; changes are usually structural 
	&nbsp;</li>
</ul>

Both acute and chronic obstruction can occur anywhere along the urinary tract and includes extrarenal and intrarenal (e.g., crystals, casts) causes. These are further subdivided into:

<ul>
	<li>Upper Urinary Tract Obstruction &ndash; includes kidney and ureter; damage is usually unilateral occurring above the vesicoureteral junction</li>
	<li>Lower urinary tract Obstruction &ndash; includes bladder and urethra; damage is usually bilateral occurring below the vesicoureteral junction</li>
	<li>Unilateral Obstruction &ndash; blockage of one of the ureters; e.g., acute unilateral obstructive uropathy means it&rsquo;s a sudden blockage in one of the tubes that drain urine from the kidneys</li>
	<li>Bilateral Obstruction &ndash; blockage of urine flow from both kidneys; e.g., chronic bilateral uropathy means it&rsquo;s a long-term blockage of urine flow from both kidneys and it slowly gets worse over time 
	&nbsp;</li>
</ul>

Obstructive uropathy can also be classified as high-grade (complete obstruction) or low-grade (partial or incomplete) obstruction.

It is important to identify the type of obstructive uropathy to determine the appropriate treatment approach. 
&nbsp;

Signs and Symptoms

Obstructive uropathy typically presents as:

<ul>
	<li>Flank pain on one or both sides of the body depending on whether one or both kidneys are involved</li>
	<li>Fever</li>
	<li>Nausea and vomiting</li>
	<li>Swelling or tenderness in the kidneys</li>
	<li>Bloody urine</li>
	<li>Cloudy urine 
	&nbsp;</li>
</ul>

Change in urinary habits, including the following, also indicate an obstruction:

<ul>
	<li>Difficulty passing urine</li>
	<li>Nocturia, i.e., an urge to urinate frequently, especially at night</li>
	<li>Feeling that bladder isn&rsquo;t empty</li>
	<li>Dribble or slowed stream</li>
	<li>Decreased urine output 
	&nbsp;</li>
</ul>

Symptoms In Fetus

The condition can also affect babies in the womb. One of the signs of obstruction will be the level of amniotic fluids. Urine is a component of amniotic fluid so, if the fetus is unable to urinate outside their body, it will automatically lead to a drop in amniotic fluid volume, which can cause birthing complications.<a href="#accordion">[23]</a> 
&nbsp;

Causes

The causes of obstructive uropathy can be broadly categorized into:

<ul>
	<li>Congenital urinary tract obstruction &ndash; some people are born with abnormalities in their urinary tract that can cause obstruction. This is mostly seen in males, usually due to pelviureteric junction or posterior urethral valve obstruction. </li>
	<li>Acquired urinary tract obstruction &ndash; this can affect either the lower or upper urinary tract and can be due to intrinsic or extrinsic causes. 
	&nbsp;</li>
</ul>

The obstruction can be caused due to:

<ol>
	<li>&nbsp;Kidney Stones: Kidney stones are hard deposits that form in the kidneys and block the flow of urine.</li>
	<li>&nbsp;Enlarged Prostate: In men, an enlarged prostate gland compresses the urethra and blocks the flow of urine.</li>
	<li>&nbsp;Ureteral Stricture: This is a narrowing of the ureter.</li>
	<li>&nbsp;Bladder Stones: These are hard deposits that form in the bladder and block the flow of urine.</li>
	<li>&nbsp;Tumors: Tumors in the urinary tract can cause a blockage.</li>
	<li>&nbsp;Urinary Tract Infections: In some cases, a urinary tract infection can cause inflammation and swelling that can block the flow of urine. 
	&nbsp;</li>
</ol>

Many conditions can cause obstructive uropathy<a href="#accordion">[24]</a>:

<ol>
	<li>&nbsp;Anatomic abnormalities, including:</li>
</ol>

<ul>
	<li>Bladder &ndash; contracture of the vesical neck</li>
	<li>Ureters &ndash; polys and stricture</li>
	<li>Urethra &ndash; abnormal anterior/posterior valve, injury (e.g., pelvic fracture), stricture (inflammatory, malignant, traumatic), diverticulum, meatal stenosis, phimosis, paraphimosis 
	&nbsp;</li>
</ul>

<ol start="2">
	<li>&nbsp;Compression due to extrinsic masses or processes</li>
</ol>

<ul>
	<li>Female reproductive system &ndash; pregnancy, abscess, tumor (ovarian, cervical), Gartner duct cyst, uterine prolapse, tubo-ovarian abscess</li>
	<li>Genitourinary tract &ndash; prostate cancer, benign prostatic hyperplasia, and prostatic or periurethral abscess</li>
	<li>Gastrointestinal tract &ndash; cyst, tumor, appendiceal abscess, diverticular abscess, Crohn&rsquo;s disease</li>
	<li>Blood vessels &ndash; aneurysm, aberrant blood vessels, retrocaval ureter, puerperal ovarian vein thrombophlebitis</li>
	<li>Retroperitoneum &ndash; tuberculosis, fibrosis (surgical, idiopathic, drug-induced), lymphoma, hematoma, metastatic tumor (breast, prostate, testicular), lymphocele, pelvic lipomatosis, sarcoidosis 
	&nbsp;</li>
</ul>

<ol start="3">
	<li>&nbsp;Functional abnormalities </li>
</ol>

<ul>
	<li>Ureters &ndash; ureteropelvic or ureterovesical junction dysfunction</li>
	<li>Bladder &ndash; drug-induced dysfunction, neurogenic bladder due to nervous system dysfunction, and bladder neck dysfunction 
	&nbsp;</li>
</ul>

<ol start="4">
	<li>&nbsp;Mechanical obstruction of the lumen of the urinary tract</li>
</ol>

<ul>
	<li>Renal tubule &ndash; uric acid crystals</li>
	<li>Renal pelvis or ureters &ndash; fungus ball, urolithiasis, blood clot, sloughed renal papillae, urothelial carcinoma 
	&nbsp;</li>
</ul>

The causes of obstructive uropathy also depend on the individual&rsquo;s age:

<ul>
	<li>Children &ndash; usually present with anatomic abnormalities, such as stricture and stenosis at the ureteropelvic or ureterovesical junction </li>
	<li>Young adults &ndash; usually present with calculi</li>
	<li>Older people &ndash; usually present with prostate cancer or benign prostatic hyperplasia, calculi, and pelvic or retroperitoneal tumors 
	&nbsp;</li>
</ul>

An anatomic fetal ultrasound screens for the condition in a fetus. A doctor can also suggest an annual ultrasound of the abdomen or pelvis for an otherwise healthy urologic patient to screen for obstruction at any level. 
&nbsp;

Diagnosis

Diagnostic tests for obstructive uropathy may include: 
&nbsp;

<ol>
	<li>&nbsp;Urinalysis: This involves analyzing a sample of urine to check for signs of infection or inflammation. A urinalysis is a simple and non-invasive test that detects the presence of blood, protein, or white blood cells in the urine.</li>
	<li>&nbsp;Blood Tests: Blood tests can help identify any abnormalities in kidney function. Serum creatinine, for instance, measures the level of creatinine in the blood. Creatinine is a waste product that is produced by the muscles and excreted by the kidneys. If the kidneys are not functioning properly due to obstructive uropathy, the level of creatinine in the blood will be elevated.</li>
	<li>&nbsp;Imaging Tests: X-rays, CT scans, and ultrasounds can help visualize the urinary tract and identify any obstructions. A CT scan is a more detailed imaging test that can provide a more comprehensive view of the urinary tract and is usually reserved for patients who have abnormal findings on a renal ultrasound or who have more complex cases of obstructive uropathy.</li>
	<li>&nbsp;Urodynamic Tests: These tests measure how well the bladder and urethra are functioning and can help identify any problems with urine flow. They include electromyography, cystometry, uroflowmetry, postvoid residual measurement, and pressure flow study.</li>
	<li>&nbsp;Cystoscopy: A cystoscopy is an invasive test that involves inserting a small tube with a camera into the urethra and bladder to inspect the urinary tract. This test is usually reserved for patients who have persistent or severe symptoms of obstructive uropathy that have not been diagnosed through other tests. 
	&nbsp;</li>
</ol>

Treatment

The treatment of obstructive uropathy depends on the underlying cause of the obstruction, the severity of the obstruction, and the presence of any associated complications. In general, the goals of treatment are to relieve the obstruction, prevent further damage to the urinary tract, and preserve kidney function. Following are some common treatment options for obstructive uropathy: 
&nbsp;

<ol>
	<li>&nbsp;Stent Placement: In some cases, a stent is inserted to relieve the obstruction and allow urine to flow freely through the urinary tract.</li>
	<li>&nbsp;Nephrostomy: If the obstruction is located higher up in the urinary tract, a nephrostomy tube may be inserted through the skin and into the kidney to bypass the obstruction and drain urine directly from the kidney.</li>
	<li>&nbsp;Surgery: In some cases, surgery is necessary to either remove the obstruction, repair damaged tissue, or correct structural abnormalities in the urinary tract. If the blockage causes severe loss of function, the kidney may need to be removed.</li>
	<li>&nbsp;Medications: Medications may be used to treat underlying conditions, such as enlarged prostate or UTIs, that contribute to obstructive uropathy. 
	&nbsp;</li>
</ol>

It is important to note that treatment for obstructive uropathy should be individualized based on the specific needs of each patient, and treatment decisions should be made in consultation with a qualified healthcare provider. 
&nbsp;

Obstructive uropathy is a condition that can lead to some serious complications if left untreated. Some of the complications associated with obstructive uropathy are: 
&nbsp;

<ol>
	<li>&nbsp;<a href="https://merisehat.pk/disease/hydronephrosis">Hydronephrosis</a>: A condition in which the kidneys become swollen due to a build-up of urine that cannot flow through the urinary tract. This can lead to kidney damage if left untreated.</li>
	<li>&nbsp;Urinary Tract Infection (UTI): Blockages in the urinary tract can increase the risk of UTIs, which can lead to further complications if left untreated.</li>
	<li>&nbsp;Kidney Damage: If left untreated, obstructive uropathy can cause irreversible damage to the kidneys, leading to a reduction in kidney function or even kidney failure.</li>
	<li>&nbsp;<a href="https://merisehat.pk/disease/chronic-kidney-disease">Chronic Kidney Disease (CKD)</a>: Obstructive uropathy can lead to the development of CKD, a condition in which the kidneys gradually lose function over time.</li>
	<li>&nbsp;Sepsis: In rare cases, obstructive uropathy can lead to the development of sepsis, a life-threatening condition in which the body&#39;s immune system overreacts to an infection.</li>
	<li>&nbsp;Bladder Damage: In some cases, obstructive uropathy can lead to bladder damage or bladder dysfunction. 
	&nbsp;</li>
</ol>

The condition can also lead to abscess formation, urinary fistula formation, bladder dysfunction secondary to the defunctionalized bladder, and urinary extravasation with urinoma formation. Also, microscopic hematuria usually develops following urethral catheterization, but more significant bleeding can also occur. Furthermore, hypotension and bradycardia can occur after the placement of the Foley. 
&nbsp;

Some common risk factors associated with obstructive uropathy include: 
&nbsp;

<ol>
	<li>&nbsp;Gender: Men are more likely than women to develop obstructive uropathy, in part because they have a longer urethra that is more prone to blockages.</li>
	<li>&nbsp;Enlarged Prostate: <a href="https://merisehat.pk/disease/benign-prostatic-hyperplasia">Benign prostatic hyperplasia (BPH)</a>, which is a non-cancerous enlargement of the prostate gland, is a common cause of obstructive uropathy in older men.</li>
	<li>&nbsp;<a href="https://merisehat.pk/disease/kidney-stones-66">Stones</a>: Kidney stones can cause obstructive uropathy by blocking the flow of urine from the kidneys to the bladder. Ureteral stones are another risk factor for obstructive uropathy.</li>
	<li>&nbsp;Cancer: Certain types of cancer, such as bladder cancer or <a href="https://merisehat.pk/disease/prostate-cancer">prostate cancer</a>, can cause obstructive uropathy by compressing or invading the urinary tract.</li>
	<li>&nbsp;Trauma: Injuries to the urinary tract, such as those caused by accidents or medical procedures, can lead to obstructive uropathy.</li>
	<li>&nbsp;Infection: Infections of the urinary tract, such as UTIs, can cause inflammation and swelling that can lead to obstructive uropathy.</li>
	<li>&nbsp;Congenital Abnormalities: Some people are born with structural abnormalities of the urinary tract that can increase the risk of developing obstructive uropathy later in life.</li>
	<li>&nbsp;Neurological Conditions: Certain neurological conditions, such as spinal cord injuries or multiple sclerosis, can interfere with the normal functioning of the urinary tract and increase the risk of obstructive uropathy. 
	&nbsp;</li>
</ol>

While there&rsquo;s no way to prevent ureteral obstruction caused by a genetic condition, GI issues, tumor, enlarged prostate, or vascular disease, it&rsquo;s possible to prevent the ureteral stones from developing. Some preventive measures that can help include: 
&nbsp;

<ol>
	<li>&nbsp;Hydration: Drinking plenty of fluids not only helps prevent the formation of kidney stones but also helps keep urine flowing freely through the urinary tract, thereby, reducing the risk of blockages or obstructions.</li>
	<li>&nbsp;Diet: Eating a healthy diet that is low in salt and animal protein can help reduce the risk of kidney stones and other conditions that can lead to obstructive uropathy.</li>
	<li>&nbsp;Exercise: Regular exercise can help maintain a healthy weight and reduce the risk of conditions, like <a href="https://merisehat.pk/disease/obesity">obesity</a>, <a href="https://merisehat.pk/disease/constipation">constipation</a>, or <a href="https://merisehat.pk/disease/diabetes-type-1-and-2">diabetes</a>, which can increase the risk of obstructive uropathy.</li>
	<li>&nbsp;Avoidance Of Bladder Irritants: Certain substances, such as caffeine, alcohol, and spicy foods, can irritate the bladder and increase the risk of conditions like UTIs, which can cause obstructive uropathy. Avoiding these substances or consuming them in moderation can help reduce the risk of bladder irritation.</li>
	<li>&nbsp;Prompt Treatment Of Utis: If a UTI does occur, it is important to seek prompt treatment to prevent the infection from spreading to the kidneys and causing obstructive uropathy.</li>
	<li>&nbsp;Regular Medical Checkups: Regular checkups with a healthcare provider can help identify and manage risk factors for obstructive uropathy, such as BPH or certain types of cancer. 
	&nbsp;</li>
</ol>

A team of researchers from Stanford University and other institutions aimed to develop a noninvasive method for diagnosing obstructive uropathy using urinary exosomal mRNA expression and machine learning analysis. They found that analysis of urinary exosomal mRNA expression using machine learning algorithms was able to accurately diagnose obstructive uropathy in both animal models and human patients. This approach can potentially replace invasive procedures such as renal biopsy and allow for earlier diagnosis and treatment of obstructive uropathy<a href="#accordion">[21]</a>. 
&nbsp;

Key Points

<ul>
	<li>Obstructive uropathy is a condition that affects the urinary system. </li>
	<li>It is characterized by an obstruction or blockage (either partial or complete) in the urinary tract that prevents urine from flowing from the kidneys to the bladder.</li>
	<li>Both acute and chronic obstruction can occur anywhere along the urinary tract and includes extrarenal and intrarenal (e.g., crystals, casts) causes.</li>
	<li>While signs and symptoms and signs of obstruction are often mild, occurring over long periods, early recognition and treatment are key to preventing renal loss.</li>
	<li>Diagnostic tests for obstructive uropathy may include urinalysis, blood tests, and imaging tests.</li>
	<li>Treatment includes the elimination of the obstruction through surgery, instrumentation (e.g., endoscopy, lithotripsy), or drug therapy (e.g., hormonal therapy for prostate cancer).&nbsp; 
	&nbsp;</li>
</ul>

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[3] Shiraishi, K., Eguchi, S., Mohri, J., Hayashi, T., & Kamiryo, Y. (2011). Nationwide survey of ureteral stones in Japan: epidemiological analysis with reference to frequency and age distribution. Urologia Internationalis, 86(2), 173-178.

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[12] Skolarikos, A., Straub, M., Knoll, T., Sarica, K., Seitz, C., Petřík, A., ... & de la Rosette, J. (2015). Metabolic evaluation and recurrence prevention for urinary stone patients: EAU guidelines. European Urology, 67(4), 750-763.

[13] Weiss, R. E., & Stoller, M. L. (2016). Urinary tract obstruction. In Campbell-Walsh Urology (11th ed., Vol. 4, pp. 2666-2700). Elsevier.

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[16] Nakada, S. Y., & Pearle, M. S. (2016). Ureteropelvic junction obstruction and ureteral stricture disease. In Campbell-Walsh Urology (11th ed., Vol. 4, pp. 1294-1326). Elsevier.

[17] Jamil, S., Imran, M. A., Shaikh, F., & Alam, M. T. (2020). Urosepsis: A review. Pakistan Journal of Medical Sciences, 36(7), S114-S119.

[18] Steinberg, P. L., Palacios, J. M., Junaid, I., & Finelli, A. (2020). Obstructive Uropathy. In Practical Urologic Cytopathology (pp. 145-161). Springer.

[19] Chang, Y. H., & Wu, H. C. (2020). Nephrostomy. In StatPearls [Internet]. StatPearls Publishing.

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[21] Tang, C., Li, Z., Li, Q., Li, Y., Zhou, Y., Zou, Q., ... & Huang, Y. (2022). Noninvasive diagnosis of obstructive uropathy using machine learning analysis of urinary exosomal mRNA expression. Science Translational Medicine, 14(628), eabm7465.