Ureteral Obstruction and Malformations Flashcards
Discuss obstructive uropathy.
Obstructive uropathy is the leading cause of chronic kidney disease in children. It may be caused by upper or lower urinary tract obstruction and most often hydronephrosis on renal ultrasound is the first indicator of obstruction. The key in management of these patients is determining if hydronephrosis is due to obstruction, and this can be done with further imaging such as a nuclear scan or magnetic resonance urography. Once obstruction is confirmed, the crucial step is to bypass the level of obstruction and drain the urinary tract so as not to compro- mise renal function.
What is the leading cause of chronic kidney disease in children?
Congenital urinary tract obstruction is the #1 cause of chronic kidney disease in males under 1 year old, and is one of the most common diagnosis in children undergoing renal transplant for end stage renal disease [1].
What are common causes of pediatric obstructive uropathy?
a. Ureteropelvic junction obstruction
b. Ureterovesical junction obstruction
c. Ureterocele
d. Ectopic ureter
e. Posterior urethral valves.
How is obstruction diagnosed?
Hydronephrosis on renal ultrasound (RUS) is usually the first indication of under- lying urinary tract obstruction.
The Society for Fetal Urology (SFU) developed a grading system for reporting hydronephrosis on RUS [2]. The higher the grade, the worse the hydronephrosis.
Grade 0: No splitting of renal pelvis
Grade 1: Splitting
Grade 2: Dilated renal pelvis and major calyces
Grade 3: Dilated renal pelvis, major and minor calyces
Grade 4: Dilated renal pelvis, major and minor calyces, thinned renal parenchyma
The Urinary Tract Dilation (UTD) classification system risk stratifies based on prenatal and postnatal RUS characteristics and anterior-posterior renal pelvis diameter (AP RPD) [3].
PRENATAL UTD CLASSIFICATION 1) UTD A1 (low risk) - AP RPD (mm): 16–27 wk: 4 to ≤7 ≥28 wk: 7 to ≤10 - Central or no calyceal dilation
2) UTD A2-3 (increased risk)
- AP RPD (mm):
16–27 wk: ≥7
≥28 wk: ≥10
- Peripheral calyceal dilation
- Parenchymal thickness abnl
- Parenchyma appearance abnl - Ureters abnormal
- Bladder abnormal
- Unexplained oligohydramnios
POSTNATAL UTD CLASSIFICATION 1) UTD P1 (low risk) - AP RPD (mm) 10 to <15 - Central calyceal dilation
2) UTD P2 (intermediate risk)
- AP RPD (mm): ≥15
- Peripheral calyceal dilation
- Ureters abnormal
3) UTD P3 (high risk)
- AP RPD (mm): ≥15
- Peripheral calyceal dilation
- Parenchymal thickness abnl
- Parenchyma appearance abnl - Ureters abnormal
- Bladder abnormal
How do you determine if hydronephrosis is due to obstruction?
Renal function and drainage must be assessed. This can be done with a MAG3 diuretic renal scan or with magnetic resonance urography (MRU).
The MAG3 scan requires an IV and a urinary catheter if not toilet trained.
The radiotracer is injected intravenously and within the first 2–3 minutes radiotracer uptake by the renal parenchyma is detected (radiotracer binds to the proximal tubules).
The differential renal function is determined at this point. Normal differ- ential renal function should be 50/50, with an accepted error of ±5%. At approximately 20 minutes, furosemide is administered intravenously and the drainage curves are analyzed.
The time is takes for half of the radiotracer to clear the renal pelvis is called the “t 1/2”.
An obstructed kidney will have a flat, or plateaued, drainage curve, and a t 1/2>20minutes.
An unobstructed kidney will have a down-slopping drainage curve and a t1/2 < 15 minutes.
Magnetic resonance urography (MRU) is a newer imaging modality that utilizes gadolinium-dTPA.
The advantage of MRU is that in addition to determining function and drainage, it also provides excellent anatomical evaluation.
The disadvantages of MRU are the need for sedation, cost, and limited availability.
What is the Whitaker test [4]?
The Whitaker test measures the pressure needed to propel fluid through the upper urinary tract at a fixed rate.
Under anesthesia, a nephrostomy tube is inserted into the renal pelvis and the collecting system is perfused at a continuous rate while simultaneously measuring the pressure in the renal pelvis.
In an obstructed system, renal pelvis pressures measure>20 cmH2O.
The invasiveness of this procedure has resulted in its limited use, however it can be helpful in equivocal cases.
Additionally, if performed in the fluoroscopy suite, simultaneous antegrade imaging studies can be obtained to help further assess the anatomy.
When should a voiding cystourethrogram (VCUG) be obtained in a patient with hydronephrosis?
According to the American Urological Association guidelines, a VCUG is rec- ommended in children with SFU grade 3 or 4 hydronephrosis [5].
This recommendation is based not only on the risk of vesicoureteral reflux (VUR), but also the potential for bladder outlet obstruction.
One should have a high index of suspicion for posterior urethral valves (PUV) if a male infant has a thickened trabeculated bladder with bilateral hydroureteronephrosis.
VCUG is the gold standard for diagnosing PUV, and imaging will show a dilated posterior urethra that funnels abruptly at the valves and a trabeculated bladder with a hypertrophied bladder neck.
Approximately 50% of patients with PUV will also have high grade VUR.
Patients with prenatally diagnosed hydronephrosis without PUV have an incidence of vesicoureteral reflux (VUR) of 16%.
VUR coexists with UPJ obstruction in approximately 10% of children.
What is the incidence of prenatal hydronephrosis?
Due to the increased use of ultrasound screening in the second trimester, the incidence of prenatal hydronephrosis is 1:100 to 1:500 [2].
What are antenatal signs of obstructive uropathy?
Prenatal ultrasound may show hydronephrosis, a distended bladder, and dilated posterior urethra (“keyhole” sign).
After 16 weeks gestation, amniotic fluid is mostly comprised of fetal urine, therefore fetuses with obstructive uropathy may have oligohydramnios.
Since amniotic fluid is vital to pulmonary development, oligohydramnios can result in pulmonary hypoplasia and there may be significant respiratory distress at birth.
Oligohydramnios can also result in Potter facies, club- feet and deformed hands, and poor abdominal muscle tone.
What is the timeline for postnatal imaging in a patient with prenatal hydronephrosis?
RUS should be obtained after 48 h of life. If the RUS is performed too early, it may underestimate hydronephrosis due to the relative oliguria shortly after birth.
If prenatal imaging in boys shows bilateral hydroureteronephrosis and/or thick- ened bladder with “keyhole” sign, a VCUG should be performed as soon as possi- ble to evaluate for PUV.
For patients with hydronephrosis that do not have PUV, a follow up RUS can be performed in 3–6 months to reassess the degree of hydronephrosis.
If hydronephrosis is persistent or worsening, a MAG-3 and/or VCUG can be ordered at this time.
Imaging can be ordered sooner if there is a clinical change, such as a febrile urinary tract infection.
What is the initial management for a patient with PUV?
First, a catheter (small feeding tube or coude catheter) should be placed to drain the bladder.
The balloon should not be inflated as this can obstruct the ureteral orifices in these small hypertrophied bladders.
Once the child is stable, they can be taken to the operating room for cystoscopy and valve ablation.
Ablation can be performed with a cold knife, bugbee, or laser.
A catheter is left in place for 24 hours after the procedure and a VCUG is performed one month after ablation to confirm success.
An alternative to valve ablation is creation of a vesicostomy.
This allows for decompression of the upper tracts and bladder, and valve ablation can be performed when the child is bigger.
Children with PUV have a 50–60% risk of UTI, therefore circumcision is recommended to reduce this risk.
What are the clinical outcomes of PUV?
Patients with PUV have renal dysplasia and require long term monitoring of renal function.
Studies have shown that the serum nadir creatinine level in the first year of life correlates with the need for renal replacement therapy (RRT), with 100% of patients with Cr > 1 requiring RRT by 10 years old [6].
Patients with PUV also have significant polyuria that worsens bladder dysfunction, and 26% of patients will require intermittent catheterization [6].
What causes UPJ obstruction?
In infants, the most common cause of UPJ obstruction is an intrinsic narrowing of the UPJ. In older children and adolescents, the most common cause is extrinsic compression from a crossing lower pole vessel.
What is the management of UPJ obstruction?
Dismembered pyeloplasty is the gold standard for the treatment of UPJ obstruction.
This can be performed open, laparoscopically, or robotically.
If a patient initially presents with uncontrollable pain or acute infection, a nephrostomy tube can be placed to decompress the collecting system until definitive surgery.
What are the principles of management for an ectopic ureter or ureterocele?
Ectopic ureters and ureteroceles are commonly associated with the upper pole of a duplex collecting system, which is evident on RUS as upper pole hydronephrosis.
The goals of management are to preserve renal function, prevent infection or reflux, and maintain urinary continence.
If there is adequate upper pole function, ureteroureterostomy or common sheath ureteral reimplant can be performed.
If there is no upper pole function, upper pole heminephrectomy is an option.
How does management of ureterocele differ from ectopic ureter?
Ureteroceles can be large and result in obstruction of the lower pole or contralateral ureter.
They can also prolapse and cause bladder outlet obstruction.
If the ureterocele is causing obstruction or if the patient is acutely ill from infection, they should be punctured endoscopically.
What is the incidence of ureteropelvic junction obstruction in children?
With ureteropelvic junction (UPJ) obstruction, there is inadequate drainage of urine from the renal pelvis, resulting in hydrostatic distention of the pelvis and intrarenal calyces.
The combination of increased intrapelvic pressure and urine stasis in the collecting ducts results in progressive damage to the kidney.
Historically, the incidence of UPJ obstruction has been estimated at 1 in 5000 live births. However, with the advent of antenatal ultrasonography (US), the prevalence of dilation has been found to be much higher. Retrospective reviews show that although the incidence of detected dilation has increased, the actual number of operations for UPJ obstruction has been relatively constant at 1 in 1250 births.
UPJ obstruction is more common in boys (2:1), and two-thirds occur on the left side.
Bilateral dilation occurs in 5–10% of patients and is much more frequently seen in younger children.
Bilateral obstruction is much less common.
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What causes ureteropelvic junction obstruction in children?
During development of the upper ureter, the lumen of the ureteral bud solidifies, which is followed by ureteral lengthening and later recanalization.
Failure to recanalize completely is thought to be the cause of most intrinsic UPJ obstructions. Other causes of intrinsic UPJ obstruction include ureteral valves, polyps, and leiomyomas.
The most common finding is ureteral narrowing of a variable length that joins the renal pelvis above the expected dependent position.
At low volume, peristaltic waves of urine cross the UPJ. However, as the flow increases beyond a certain threshold, the renal pelvis dilates. The dilated pelvis may kink the ureter further, increasing the pressure in the pelvis.
In 20–30% of patients, the ureter is draped over a lower-pole vessel, producing an extrinsic UPJ obstruction. In most of these patients, there is also a coexisting intrinsic narrowing of the ureter.
Histologic evaluation reveals a decrease or complete absence of smooth muscle fibers at the UPJ.
Electron microscopy may show an increase in collagen deposition between the muscle fibers that is most likely a response to the obstruction as opposed to the cause.
Fibrosis and interruption of the smooth muscle continuity block transmission of the peristaltic wave, while defective innervation also may play a role.
UPJ obstruction also can be secondary (i.e., related to other ureteral pathology). It can be found in conjunction with high-grade vesicoureteral reflux (VUR), after cutaneous ureterostomy, and after decompression of the dilated urinary tract.
VUR has been found in 15% of patients with UPJ obstruction.
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How does ureteropelvic junction obstruction present in children?
Most renal dilation and obstruction are detected prenatally.
Less frequently, it is detected because of an abdominal mass, urinary tract infection (UTI), or associated with other congenital anomalies (i.e., VACTERL [vertebral, anal, cardiac, tracheoesophageal fistula, renal, limb] syndrome).
In older children, vague, poorly localized, cyclic or acute abdominal pain associated with nausea is common. Some of these children are initially seen by gastroenterologists for their symptoms.
The cause of the intermittent obstruction is unclear, but renal function is almost always preserved.
Hematuria after minor trauma or vigorous exercise can be a presenting feature, most likely secondary to rupture of mucosal vessels in the dilated collecting system.
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How is UPV junction obstruction diagnosed?
When the antenatal diagnosis of UPJ obstruction is made, the initial postpartum evaluation should be performed at 10–14 days of life to avoid false-negative studies resulting from the transitional nephrology of the newborn.
Bilateral renal pelvis dilation is rarely associated with significant enough obstruction to cause oligohydramnios and warrant antenatal intervention.
US confirms the presence of pelvic and calyceal dilation, with variable thinning of the renal parenchyma. US is useful for evaluating the contralateral kidney, the bladder, and the distal ipsilateral ureter to avoid confusion with a ureterovesical junction (UVJ) obstruction, but it does not provide functional information.
The Society for Fetal Urology (SFU) classification has typically been used to describe the degree of dilation (Fig. 54.4).
A newer urinary tract dilation (UTD) classification system is gaining favor across specialties including obstetrics, radiology, and urology as a way to standardize terminology for pre- and postnatal imaging (Table 54.1).
The presence of corticomedullary junctions is indicative of preserved function.
In the past, routine antibiotic prophylaxis was given to all infants with prenatal pelvic dilation, but the risk of a UTI is very small in the absence of reflux.
A voiding cystourethrogram (VCUG) was also previously recommended in all patients being evaluated for UPJ obstruction, as VUR increases the chance that infection will occur, even in a partially obstructed system. Between 5% and 30% of infants with prenatally detected dilation will have reflux, and the majority will spontaneously resolve without an infection. Children with isolated pyelectasis and no ureteral dilation have a very low incidence of reflux, and the clinical yield from a screening VCUG is low.
The diuretic isotopic renogram is very useful for evaluating hydronephrosis, differential renal function, and renal drainage. In this study, the transit of an injected radioisotope through the urinary tract is monitored by a gamma camera. The early uptake (first 1–2 minutes) of the tracer indicates the split renal function, while the washout, augmented by the administration of a diuretic, is plotted by a computer to evaluate drainage. The study is obtained with either 99m Tc-mercaptoacetyltriglycine (99m Tc-MAG3), whose clearance is predominantly via proximal tubular secretion, or with technetium-99m-labeled diethylenetriamine pentaacetic acid (99m Tc-DTPA), whose renal clearance is by glomerular filtration. 99m Tc-MAG3 is more efficiently excreted than 99m Tc-DTPA and gives better images, particularly in patients with impaired renal function.
The technique for diuretic renography is standardized.
Patients should be hydrated intravenously (15 mL/kg) 15 minutes before injection of the radionuclide.
An indwelling catheter maintains an empty bladder and monitors urine output.
The diuretic (1 mg/kg furosemide, up to 40 mg) is not administered until the activity peaks in the hydronephrotic kidney and renal pelvis.
The tracer activity is then monitored for an additional 30 minutes, and a quantitative analysis is performed.
Historically, persistence of >50% of the tracer in the renal pelvis 20 minutes after diuretic administration ( t 1 / 2 > 20 ) is diagnostic of obstruction, although the applicability of this threshold in pediatric patients is debatable. False-positive results may occur when the immature neonatal kidney fails to respond to diuretic, when the diuretic is administered prior to maximal renal pelvic distension, when the patient is dehydrated, when the bladder is distended, or when the renal pelvis is significantly dilated.
Magnetic resonance urography (MRU) can be used at any age. T2-weighted images are independent of renal function, and hydronephrosis is readily detected. The anatomic images are excellent. Enhanced MR images with gadolinium can give information regarding differential function if one kidney is anatomically and functionally normal, and combines detailed anatomic and functional data with a single study. These potential advantages of MR imaging must be weighed against its high cost, need for sedation or general anesthesia, and long study times. These drawbacks limit its use for isolated unilateral renal dilations, but it may be valuable in cases with unusual or complex anatomy.
Rarely, when imaging is equivocal, invasive pressure flow studies may be indicated. These tests assume that obstruction produces a constant restriction to outflow that necessitates elevated pressure to transport urine at high flow rates. However, not all obstructions are constant. If the obstruction is intrinsic, a linear relationship exists between pressure and flow. However, in some cases, the results may reflect only the response of the renal pelvis to distention and may be positive in the absence of obstruction. These studies require general anesthesia in children and have limited applicability.
Retrograde urography at the time of operative correction is helpful if uncertainty exists regarding the site of obstruction. This is rarely required because a well-performed US evaluation and radionuclide study will exclude distal obstruction. As there are risks with using instruments in the infant male urethra and the ureteral orifice, these retrograde studies are not routinely performed.
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What are the indications for operative intervention in UPJ obstruction?
Intermittent obstruction and pain are probably the most reliable indication for operation.
Diminished function, delayed drainage, progression of pelvic and calyceal dilation on US, and loss of renal function are all potential indicators of obstruction.
Randomization to operative and observational arms is complicated by a difficult decision that a parent has to make for the asymptomatic child.
The morphologic appearance of a dilated renal pelvis on excretory urography or US is not a good indication for operation because many of these findings will resolve without an operation. Neonatal hydronephrosis can often be explained by physiologic polyuria and natural kinks and folds in the ureter.
The ongoing debate in the management of neonatal UPJ obstruction centers on the definition of significant obstruction. Some authors have tried to set objective criteria for predicting the need for operative intervention such as renal pelvis diameter, renal parenchymal measurements, or differential renal function, but the inherent limitations in renography still leave questions in these studies as to whether every child that progressed to operation absolutely needed it.
Diuretic renography has limitations in the neonate, although using the “well-tempered” approach increases its value.
The standard half-time of 20 minutes for obstruction in the neonate is misleading in many cases.
Differential renal function or individual kidney uptake is the most useful information obtained during renography. An indication for operation is diminished renal function in the presence of an obstructive pattern on
renography.
Although the threshold is arbitrary, most pediatric urologists believe that <35–40% function in the hydronephrotic kidney warrants correction. However, in one study looking at patients with dilated kidneys and no more than 25% total renal function, they were found to improve to >40% of total function in all cases without operative correction.
Long-term studies of kidneys with >40% function have shown that fewer than 15–20% will require operation for diminishing function, UTIs, or unexplained abdominal pain. Some of these kidneys will regain some of the lost function.
The concern with an observational approach is that delaying correction until there is measurable deterioration in the renal function is not optimal. In the past, urinary stasis (infection, calculi, hypertension, and pain) was the indication for operative correction.
Whether more emphasis should be placed on stasis and less emphasis on differential renal function is an unanswered question.
Pyeloplasty can be safely performed in the infant. Early intervention eliminates the indefinite period of surveillance. The decision to follow neonates nonoperatively requires vigilance and parental cooperation to avoid complications.
There has been increasing interest in recent years in utilizing serum or, ideally, noninvasive urine biomarkers as an adjunct to imaging to determine the need for surgical correction. Potential candidate markers include transforming growth factor (TGF)-β1, monocyte chemotactic protein (MCP)-1, endothelin-1, and carbohydrate antigen (CA) 19-9, but these efforts are still in the investigational phase and are not widely used in clinical practice.
If the child is initially seen with acute pain or infection, it is advisable to wait 1–2 weeks to allow the inflammation to resolve.
Percutaneous drainage or stent placement for sepsis is rarely required preoperatively. It should be avoided in the absence of infection because of the inflammation that develops from a tube in the renal pelvis.
Exploration for a poorly functioning kidney requires an assessment of the renal parenchyma. If the parenchyma is grossly dysplastic or frozen-section analysis shows dysplasia, then nephrectomy should be performed.
Unfortunately, no test accurately predicts recovery of function. Thus, nephrectomy is rarely performed in the infant with UPJ obstruction.
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What are the surgical approaches to UPJ obstruction?
A dismembered pyeloplasty is the preferred technique to correct UPJ obstruction.
A successful outcome is achieved with construction of a funnel-shaped, dependent UPJ complex.
The renal pelvis and upper ureter are mobilized, and the ureter is divided just below the obstructed segment. It is spatulated on its lateral border through the aperistaltic segment. It is sometimes necessary to resect some of the renal pelvis to avoid postoperative obstruction. If this segment is particularly long, a flap of renal pelvis can be created. The Foley YV-plasty and the Culp spiral flap techniques were designed to maintain the continuity of the ureter and the pelvis. These techniques are used in unusual cases of malrotation, fusion anomalies, or long, stenotic segments.
The anastomosis is usually performed with 6-0 polydioxanone or 6-0 polyglycolic acid. The anastomosis begins at the most dependent portion of the pyeloplasty with placement of interrupted everting sutures that do not bunch the tissues and cause obstruction.
After the anastomosis to the dependent portion of the pelvis is completed, the remainder of the ureter and pelvis can be approximated with continuous suture, taking care to irrigate any clots from the pelvis before the closure is completed. It is not necessary to pass a catheter distally into the bladder because preoperative studies should have excluded a distal obstruction.
Pyeloplasties are frequently performed without diversion, so it is important to be as gentle as possible. Excessive handling of the pelvis and ureter increases edema.
A stent is typically left after a laparoscopic repair. Even if an anastomotic leak occurs, a satisfactory outcome usually results.
A Penrose drain may be left near the anastomosis and can usually be removed within 48 hours. If drainage is prolonged, the child can be discharged with the drain in place. Renal drainage is definitely indicated in solitary kidneys or when simultaneous bilateral pyeloplasties are performed.
In a reoperation, it is technically more difficult to achieve a watertight anastomosis and internal drainage (stent, nephrostomy or nephrostent) is indicated.
Extrinsic UPJ obstruction associated with an aberrant lower-pole vessel requires division of the ureter at the UPJ and performance of a standard dismembered pyeloplasty after transposing the ureter to a nonobstructed position. This technique is the standard laparoscopic approach and is preferable to transposition of the crossing vessel.
In the case of an intrarenal pelvis or when significant scarring is found at reoperation, a ureterocalicostomy is a useful technique. A portion of the lower pole should be resected to prevent a postoperative stricture. The ureter is spatulated and then anastomosed to the exposed calyx in the lower pole.
Laparoscopic pyeloplasty has been performed in all ages, and the age of the patient is inversely related to benefits of decreased pain and convalescence.
However, the open approach still has a role in infants and young children. Open pyeloplasty can be performed through a flank, anterior extraperitoneal approach, or posterior lumbotomy approach.
The anterior approach involves a transverse incision from the edge of the rectus to the tip of the 12th rib. The retroperitoneum is entered and the UPJ is exposed, with the kidney left in situ. In infants, this is a musclesplitting incision with low morbidity.
The dorsal lumbotomy approach also can be easily performed in infancy and provides direct access to the UPJ. The kidney does not require mobilization, and the ureter and renal pelvis can usually be delivered out of the incision. In bilateral cases, the child does not need to be repositioned. The lumbotomy approach should not be used with a malrotated kidney or a kidney that has an intrarenal pelvis.
For a second operation, when an open approach is used, the anterior or flank approach is typically preferred over the dorsal lumbotomy technique. However, laparoscopy and endopyelotomy have seen increasing use in reoperative pyeloplasty.
Endoscopic approaches (endopyelotomy) for UPJ obstruction were popularized in the 1980s and 1990s but have been replaced by laparoscopic approaches.
Endopyelotomy successfully relieves primary UPJ obstruction in 70% of children. As this success pales in comparison to pyeloplasty, it is not routinely utilized for primary repair. Endopyelotomy clearly has a role in recurrent UPJ obstruction, in which the success rate is >95%. Depending on the age of the patient and the size of the ureter, this can be performed in either an antegrade or retrograde fashion.
The first laparoscopic pyeloplasty in a child was reported in 1995 by Peters et al., and the first series was published by Tan in 1999. Laparoscopic pyeloplasty has been reported in children as young as 2 months.
The introduction of robotic surgery with articulating instruments and three-dimensional visualization has made intracorporeal suturing easier and more precise.
The success rates of open, laparoscopic, and robotic pyeloplasties are equivalent. Robotic instrumentation adds cost but may decrease the hospitalization or minor postoperative complications according to some authors.
The benefits of laparoscopic and robotic surgery over an open approach may include a decreased length of hospitalization, decreased analgesic requirements, improved cosmesis, and quicker return to normal activity, which likely have increasing benefit with increasing age of the patient.
Laparoscopic pyeloplasties are mostly performed using the Anderson–Hynes dismembered technique. This can be performed through either a transperitoneal or retroperitoneal approach using a similar technique once access and exposure are obtained. With both transabdominal and retroperitoneal approaches, the child is placed on the operating table in a flank or modified flank position.
H&A
How do you managed UPJ obstruction in a duplex kidney?
In a duplex kidney, the lower pole is most commonly affected because the upper pole lacks a true renal pelvis.
US may not be reliable for diagnosis because the duplex nature of the kidney may not be identified.
A pyelogram or renogram will show a small nonobstructed upper segment.
The anatomy of the duplication dictates the operation. If the ureter is incompletely duplicated and a long lower-pole ureteral segment is found, a standard dismembered pyeloplasty can be performed.
If a high bifurcation with a short distal segment is present, then the end of the renal pelvis can be anastomosed to the side of the upper-pole ureter.
The appropriate technique can be determined after the kidney and pelvis are exposed.
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What are complications from UPJ obstruction surgery?
The results of operative correction for UPJ obstruction have been uniformly successful when performed at children’s hospitals.
The rate of recurrent UPJ obstruction is <1%, and the nephrectomy rate is <2%.
The most common early complications are prolonged urinary extravasation and delayed drainage through the anastomosis.
If a significant leak develops, either a stent or a percutaneous nephrostomy tube can be inserted.
Once diversion is instituted, the leak will usually cease within 48 hours.
Late scarring at the anastomotic site is common, but rarely occurs due to a leak.
Delayed opening of the anastomosis is seen most commonly when a nephrostomy tube is used. When this occurs, patience is important because 80% of these will open within 3 months.
Secondary obstruction or failure of the primary procedure occurs due to scarring or fibrosis, a nondependent anastomosis, ureteral angulation secondary to renal malrotation, or ureteral narrowing distal to the anastomosis.
Typically a functional assessment of the anastomosis with nuclear renography is obtained 2–3 months after the operation. Further evaluation is then recommended 12–24 months after surgery, with problems being uncommon after this time in the absence of symptoms.
Recently there has been a move to decrease the cost and radiation associated with evaluating an operation that has a success rate >95%. Several authors have reported favorable results when the patients are followed with US alone and postoperative renography is avoided in asymptomatic patients. However, the benefits of avoiding the radiation and invasive nature of renography must be balanced against the risk of not objectively measuring differential function and drainage postoperatively.
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