Pelviureteric junction obstruction
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A pelviPelvi-ureteric junction (PUJ) obstruction can be one of the causes of an obstructive uropathy. It can be congenital or acquired with a congenital PUJ obstruction being one of the commonest causes of antenatal hydronephrosis.
Epidemiology
It may present in both paediatric and adult populations although they tend to have differing aetiology. The condition is commonly unilateral.
The estimated incidence in pediatric population is at ~ 1~1 per 1000 - 2000-2000 newborns 9 and~ 67~67% of cases) and a male predominance.
Clinical presentation
Many cases are asymptomatic and identified incidentally when the renal tract is imaged for other reasons. When symptomatic, symptoms include recurrent urinary tract infections, stone formation and even a palpable flank mass.
Classically intermittent pain after drinking large volumes of fluid or fluids with a diuretic effect is described, due to the reduced outflow from the renal pelvis into the ureter 8.
Pathology
During embryogenesis, the pelvi-ureteric junction forms usually around the fifth week and the initial tubular lumen of the ureteric bud becomes recanalised by ~ 10 - 12~10-12 weeks. The PUJ area is the last to recanalize. Inadequate canalization is thought to be the main embryological explanation of a PUJ obstruction. Extrinsic obstructions secondary to bands, kinks, and aberrant vessels also are commonly encountered.
Causes
-
congenital (neonatal)
- idiopathic and often unknown; proposed causes include
- abnormal muscle arrangement at the PUJ
- anomalous collagen collar at PUJ
- ischaemic insult to PUJ region
- urothelial ureteral fold
- idiopathic and often unknown; proposed causes include
-
adult
- preceding renal pelvic trauma
- obstructing calculus immediately distal to PUJ
- previous pyelitis with scarring
- intrinsic malignancy
:, e.g. upper tract urothelial carcinoma - extrinsic ureter compression of encasement
- fibrosis
- malignancy
Associations
- In congenital cases, a number of rental tract abnormalities are recognised, including
: - in
~ 40~40% of cases, an aberrant, accessory, or early-branching lower pole segment vessel is found and observed to compress the ureter, causing mechanical obstruction
Radiographic features
IVU
Traditionally intravenous urogram (IVU) has been performed for assessing for PUJ obstruction. The administration of frusemide is used to assist confirming the diagnosis, in particular to exclude a so called 'baggy pelvis'.
Ultrasound
- will often show a dilated renal pelvis with a collapsed proximal ureter
- with Doppler sonography the obstructed kidneys can show show higher RI's (resistive indices).
CT
May show evidence of hydronephrosis +/- calyectasis with collapsed ureters. Useful for assessing crossing vessels at the PUJ especially when surgical intervention is planned 5,7.
Scintigraphy
Scintigraphy can quantitate the degree of obstruction:
- 99mTc diethylenetriaminepentaacetic acid (DTPA): Not the agent of choice because of 99mTc-DTPA pure GFR filtration. Glomerular function declines earlier and more rapidly than does tubular function in obstructive uropathy. 99mTc-DTPA can be used if good renal function.
- 99mTc MAG3: Agent of choice for reasons stated above. Diuretic (Furosemide) Renogram is performed to evaluate between obstructive vs nonobstructive hydronephrosis. PUJ "obstruction" will demonstrate excretion (downward slope on renogram) after administration of diuretic from the collecting system. Where as mechanical obstructive hydronephrosis will demonstrate no downward slope on renogram, with retained tracer in collecting system.
Treatment and prognosis
Treatment depends on the underlying cause. In a majority of congenital cases, the condition is essentially benign and usually no intervention is required. However when there is a definitive structural obstruction (commonly adult cases), surgical intervention with pleyoplasty or stenting may be required.
Differential diagnosis
General imaging differential considerations include:
- congenital megacalyectasis: central renal pelvis tends to be relatively collapsed
- extra renal pelvis
-<p>A <strong>pelvi-ureteric junction (PUJ) obstruction</strong> can be one of the causes of an <a href="/articles/obstructive-uropathy">obstructive uropathy</a>. It can be congenital or acquired with a congenital PUJ obstruction being one of the commonest causes of <a href="/articles/fetal-hydronephrosis">antenatal hydronephrosis</a>.</p><h4>Epidemiology</h4><p>It may present in both paediatric and adult populations although they tend to have differing aetiology. The condition is commonly unilateral.</p><p>The estimated incidence in pediatric population is at ~ 1 per 1000 - 2000 newborns <sup>9</sup> and there is a recognised predilection towards the left side (~ 67% of cases) and a male predominance. </p><h4>Clinical presentation</h4><p>Many cases are asymptomatic and identified incidentally when the renal tract is imaged for other reasons. When symptomatic, symptoms include recurrent <a href="/articles/paediatric-urinary-tract-infection-2">urinary tract infections</a>, stone formation and even a palpable flank mass.</p><p>Classically intermittent pain after drinking large volumes of fluid or fluids with a diuretic effect is described, due to the reduced outflow from the renal pelvis into the ureter <sup>8.</sup></p><h4>Pathology</h4><p>During embryogenesis, the pelvi-ureteric junction forms usually around the fifth week and the initial tubular lumen of the ureteric bud becomes recanalised by ~ 10 - 12 weeks. The PUJ area is the last to recanalize. Inadequate canalization is thought to be the main embryological explanation of a PUJ obstruction. Extrinsic obstructions secondary to bands, kinks, and aberrant vessels also are commonly encountered. </p><h5>Causes</h5><ul>- +<p><strong>Pelvi-ureteric junction (PUJ) obstruction</strong> can be one of the causes of an <a href="/articles/obstructive-uropathy">obstructive uropathy</a>. It can be congenital or acquired with a congenital PUJ obstruction being one of the commonest causes of <a href="/articles/fetal-hydronephrosis">antenatal hydronephrosis</a>.</p><h4>Epidemiology</h4><p>It may present in both paediatric and adult populations although they tend to have differing aetiology. The condition is commonly unilateral.</p><p>The estimated incidence in pediatric population is at ~1 per 1000-2000 newborns and there is a recognised predilection towards the left side (~67% of cases) and a male predominance. </p><h4>Clinical presentation</h4><p>Many cases are asymptomatic and identified incidentally when the renal tract is imaged for other reasons. When symptomatic, symptoms include recurrent <a href="/articles/paediatric-urinary-tract-infection-2">urinary tract infections</a>, stone formation and even a palpable flank mass.</p><p>Classically intermittent pain after drinking large volumes of fluid or fluids with a diuretic effect is described, due to the reduced outflow from the renal pelvis into the ureter <sup>8</sup>.</p><h4>Pathology</h4><p>During embryogenesis, the pelvi-ureteric junction forms usually around the fifth week and the initial tubular lumen of the ureteric bud becomes recanalised by ~10-12 weeks. The PUJ area is the last to recanalize. Inadequate canalization is thought to be the main embryological explanation of a PUJ obstruction. Extrinsic obstructions secondary to bands, kinks, and aberrant vessels also are commonly encountered. </p><h5>Causes</h5><ul>
-<li>intrinsic malignancy : e.g. <a href="/articles/upper-tract-urothelial-carcinoma">upper tract urothelial carcinoma</a>- +<li>intrinsic malignancy, e.g. <a href="/articles/upper-tract-urothelial-carcinoma">upper tract urothelial carcinoma</a>
-<li>In congenital cases, a number of rental tract abnormalities are recognised, including:<ul>- +<li>In congenital cases, a number of rental tract abnormalities are recognised, including<ul>
-<li>in ~ 40% of cases, an aberrant, accessory, or early-branching lower pole segment vessel is found and observed to compress the ureter, causing mechanical obstruction</li>- +<li>in ~40% of cases, an aberrant, accessory, or early-branching lower pole segment vessel is found and observed to compress the ureter, causing mechanical obstruction</li>
-</ul><h5>CT</h5><p>May show evidence of hydronephrosis + / - calyectasis with collapsed ureters. Useful for assessing crossing vessels at the PUJ especially when surgical intervention is planned <sup>5,7</sup>.</p><h5>Scintigraphy</h5><p>Scintigraphy can quantitate the degree of obstruction</p><ul>- +</ul><h5>CT</h5><p>May show evidence of hydronephrosis +/- calyectasis with collapsed ureters. Useful for assessing crossing vessels at the PUJ especially when surgical intervention is planned <sup>5,7</sup>.</p><h5>Scintigraphy</h5><p>Scintigraphy can quantitate the degree of obstruction:</p><ul>
-<sup>99m</sup>Tc diethylenetriaminepentaacetic acid (DTPA) : Not the agent of choice because of <sup>99m</sup>Tc-DTPA pure GFR filtration. Glomerular function declines earlier and more rapidly than does tubular function in obstructive uropathy. <sup>99m</sup>Tc-DTPA can be used if good renal function. </li>- +<sup>99m</sup>Tc diethylenetriaminepentaacetic acid (DTPA): Not the agent of choice because of <sup>99m</sup>Tc-DTPA pure GFR filtration. Glomerular function declines earlier and more rapidly than does tubular function in obstructive uropathy. <sup>99m</sup>Tc-DTPA can be used if good renal function. </li>
-<sup>99m</sup>Tc MAG3 : Agent of choice for reasons stated above. Diuretic (Furosemide) Renogram is performed to evaluate between obstructive vs nonobstructive hydronephrosis. PUJ "obstruction" will demonstrate excretion (downward slope on renogram) after administration of diuretic from the collecting system. Where as mechanical obstructive hydronephrosis will demonstrate no downward slope on renogram, with retained tracer in collecting system.</li>-</ul><h4>Treatment and prognosis</h4><p>Treatment depends on the underlying cause. In a majority of congenital cases, the condition is essentially benign and usually no intervention is required. However when there is a definitive structural obstruction (commonly adult cases), surgical intervention with pleyoplasty or stenting may be required. </p><h4>Differential diagnosis</h4><p>General imaging differential considerations include</p><ul>- +<sup>99m</sup>Tc MAG3: Agent of choice for reasons stated above. Diuretic (Furosemide) Renogram is performed to evaluate between obstructive vs nonobstructive hydronephrosis. PUJ "obstruction" will demonstrate excretion (downward slope on renogram) after administration of diuretic from the collecting system. Where as mechanical obstructive hydronephrosis will demonstrate no downward slope on renogram, with retained tracer in collecting system.</li>
- +</ul><h4>Treatment and prognosis</h4><p>Treatment depends on the underlying cause. In a majority of congenital cases, the condition is essentially benign and usually no intervention is required. However when there is a definitive structural obstruction (commonly adult cases), surgical intervention with pleyoplasty or stenting may be required. </p><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>
-<a href="/articles/congenital-megacalyces">congenital megacalyectasis</a> : central renal pelvis tends to be relatively collapsed</li>- +<a href="/articles/congenital-megacalyces">congenital megacalyectasis</a>: central renal pelvis tends to be relatively collapsed</li>
References changed:
- 9. Guiberteau MJ. Essentials of Nuclear Medicine Imaging: Expert Consult - Online and Print, 6e. Saunders. ISBN:1455701041. <a href="http://books.google.com/books?vid=ISBN1455701041">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/1455701041">Find it at Amazon</a><span class="auto"></span>
- 9. Eurorad teaching files : <a href="http://www.eurorad.org/eurorad/case.php?id=5801&lang=en"> Case 5801</a> showing PUJ obstruction in utero
- 10. MPH FAMJMD, Guiberteau MJ. Essentials of Nuclear Medicine Imaging: Expert Consult - Online and Print, 6e. Saunders. ISBN:1455701041. <a href="http://books.google.com/books?vid=ISBN1455701041">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/1455701041">Find it at Amazon</a><span class="auto"></span>
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