Ureteropelvic Junction Obstruction

Etiology

Classification

Congenital/primary vs. acquired/secondary or intrinsic vs. extrinsic
- Most cases are congenital, but may only become clinically apparent much later in life
  - UPJO in neonates is most frequently found as a result of maternal-fetal ultrasound
    - Many newborns diagnosed with hydronephrosis on ultrasound are subsequently found to have UPJO

Congenital

SHAVA (5)

True ureteral Stricture
High insertion found more frequently in the presence of renal ectopia or fusion anomalies
Aberrant vessels (controversy persists). Regardless, the presence of crossing vessels has a detrimental effect on the success rates of endopyelotomy
Kinks or Valves produced by infoldings of the ureteral mucosa and muscularis
Aperistaltic segment

UPJO in newborns and infants is most often caused by an intrinsic narrowing
- The ureteral segment has an interruption in the development of the circular musculature of the UPJ and an alteration in collagen fibers in and around the muscular cells. This results in a narrowed segment of the UPJ with functional discontinuity of the muscular contractions and ultimately to insufficient emptying of the renal pelvis
UPJO in childhood and adolescence is often extrinsic narrowing caused by an accessory vessel to the lower pole of the kidney giving rise to flank pain, nausea, and vomiting.
- Extrinsic obstruction seen in association with a lower pole vessel (aberrant, accessory, or early branching) that passes anteriorly to the UPJ or proximal ureter and contributes to mechanical obstruction
Congenital renal malformations commonly associated with UPJO (8):
1. Contralateral UPJO (most common anomaly)
2. Renal dysplasia
3. Multicystic dysplastic kidneys
4. Renal agenesis
5. Horseshoe kidneys
6. VUR
7. Ectopic kidney
8. Duplex kidney

Acquired

CRIIBS (5)

Cancer
Vesicoureteral Reflux; can lead to upper tract dilation with subsequent elongation, tortuosity, and kinking or narrowing of the UPJ
Post-Inflammatory or postoperative scarring or Ischemia
Benign lesion (e.g. fibroepithelial polyps)
Stones

=== Intermittent UPJO ===*Dietl's crisis is intermittent abdominal pain associated with nausea and vomiting following an episode of high fluid intake.

Although a renal scan with Lasix is used in an attempt to prompt the crisis, it may on occasion be falsely negative.
In these patients, it is best to repeat a renal ultrasound at the time of pain and compare this to a baseline renal ultrasound taken when the patient was asymptomatic. If increased hydronephrosis at the time of symptoms is present, it is diagnostic and the pyeloplasty will be curative.

Diagnosis and Evaluation

History and Physical Exam

History
- Signs and Symptoms§
  1. Periodic abdominal pain (loin pain), usually after diuresis
  2. Vomiting
  3. Recurrent pyelonephritis
  4. Fever
  5. Uncommonly, abdominal mass, or hematuria secondary to infection

Labs

Serum creatinine
- Assess of baseline renal function

Imaging

Performed to determine the anatomic site and functional significance of an apparent obstruction

Contrast-enhanced axial imaging

CT/MR urography

Nuclear diuretic renography

Commonly used for diagnosing both UPJ and ureteral obstruction
Most commonly used agent in renogram studies is technetium 99m mercaptoacetyltriglycine (99m Tc-MAG3), especially in the pediatric population§
- In the adult population, other agents can be used, such as diethylenetriamine pentaacetate (DTPA)
Provides quantitative data regarding differential renal function and obstruction, even in hydronephrotic renal units (see Pathophysiology of UUT Obstruction Chapter Notes for nuclear imaging details)
- In general, kidneys with < 15% differential function are nonsalvageable in adults (Chapter 48 suggests <10%).
  - If the potential for salvageability of function is still unclear, an internal stent or percutaneous nephrostomy may be placed for temporary relief of obstruction and renal function studies subsequently repeated

Management

Indications for interventions

Similar to diversion for ureteric stone + HTN (5):

Symptoms associated with the obstruction
Stones
Infection
Renal dysfunction
Causal hypertension

Options

Observation
- If patient is asymptomatic and the physiologic significance of the obstruction seems indeterminate, careful observation with serial follow-up renal scans is appropriate
Intervention (4):
1. Decompression (ureteral stent or nephrostomy tube)
2. Endourological procedures (balloon dilation or endopyelotomy)
3. Pyeloplasty
4. Ureterocalycostomy

Endourologic procedures

Options (2):
1. Balloon dilation
2. Endopyelotomy
Advantages:
1. Less invasive
2. Reduced hospital stays and postoperative recovery
Disadvantages (2):
1. Higher risk of failure than pyeloplasty
  - Patients should be counseled that the success rate of any endourologic approach may be less than that of formal reconstruction.
    - Success rates approach 85-90% for percutaneous endopyelotomy
2. Requires taking into account the degree of hydronephrosis, ipsilateral renal function, concomitant calculi, and possibly the presence of crossing vessels, whereas pyeloplasty (open, laparoscopic, or robotic) can be applied to almost any anatomic variation of UPJO
  - Moderate to severe hydronephrosis is most predictive of failure after percutaneous endopyelotomy
Transplantation complications are particularly suited to endoscopic (antegrade or retrograde) management
Approaches:
- Retrograde balloon dilation alone
  - Long-term follow-up studies have shown a diminishing success rate over time
- Endopyelotomy
  - Contraindications (3):
    1. >2 cm of obstruction
    2. Untreated UTI
    3. Untreated coagulopathy
  - Technique
    - Approaches: percutaneous antegrade or retrograde ureteroscopic
      - Retrograde endopyelotomy
        Advantage
        No need for percutaneous access
        
        Allows direct visualization of the UPJ and assurance of a properly situated, full-thickness endopyelotomy incision
      - Percutaneous endopyelotomy
        Advantage
        Appropriate for patients with UPJO and concomitant pyelocalyceal stones, which can be managed simultaneously.
    - Methods: can be done with an endopyelotome, holmium laser or cutting balloon catheter
      - Cutting balloon catheters have the potential to better dilate ischemic and fibrotic lesions resistant to conventional balloon catheter dilation[1]
      - Little evidence for significant differences in success among endopyelotomy techniques.
        Differences lie in technical considerations and complications.
      - If using an endopyelotome or laser, a full-thickness lateral incision is made through the obstructing proximal ureter, from the ureteral lumen out to the peripelvic and periureteral fat
        Incision should usually be made laterally because this is the location devoid of crossing vessels
    - A stent is placed across the incision and is left to heal.
      - No consensus as to the optimal stent size or duration after endopyelotomy
  - Postoperative care
    - Avoidance of strenuous activity for 8-10 days after the procedure
    - Once the stent is removed, that patient returns 1 month later for history and physical exam, urinalysis, and diuretic renography
    - For most adults, 2-3 year follow-up is justified
      - Studies indicate that even at 36 months some late failures are identified, but relatively few are identified at 60 months
  - Adverse events
    - Early
      1. Bleeding requiring transfusion
      2. Urinary leak
      3. Drainage-related complications
      4. Hydropneumothorax
        Risk is increased if upper pole access is used
    - Late
      1. Recurrent obstruction
        Options if percutaneous endopyelotomy fails:
        Retrograde endopyelotomy
        
        Repeat percutaneous endopyelotomy
        
        Laparoscopic, robotic, or open operative intervention

Pyeloplasty

Principles of UPJ anastomosis (5):
1. Widely patent
2. Watertight
3. Without tension
4. Heal over a stent
5. Reconstructed UPJ should allow a funnel-shaped transition between the pelvis and the ureter that is in a position of dependent drainage
Absolute contraindications (3):
1. Untreated UTI
2. Uncorrected coagulopathy
3. Cardiopulmonary compromise unsuitable for surgery
Technique
- Before definitive surgical management, drainage of a kidney with UPJO is recommended only for infection associated with the obstruction or renal dysfunction resulting from obstruction in a solitary kidney or bilateral disease [suggesting no stent in renal dysfunction from single side obstruction if contralateral kidney fine]
- Approaches: transperitoneal, retroperitoneal, or anterior extraperitoneal
  - Transperitoneal laparoscopic approach is the most widely used method due to its associated large working space and familiar anatomy.
  - Retroperitoneal laparoscopic approach and anterior extraperitoneal approach rely on creation of a working space using manual or balloon dilation.
- Methods: dismembered vs. non-dismembered
  - Dismembered pyeloplasty
    - Example: Anderson-Hynes pyeloplasty
    - Preferred by most urologists because this procedure is almost universally applicable to different clinical scenarios
      - Can be used regardless of whether the ureteral insertion is high on the pelvis or already dependent.
      - Permits reduction of a redundant pelvis or straightening of a tortuous proximal ureter
      - Anterior or posterior transposition of the UPJ can be achieved when the obstruction is the result of accessory or aberrant lower pole vessels
        In the presence of crossing aberrant or accessory lower pole renal vessels associated with UPJ obstruction, a dismembered pyeloplasty is the only method to allow transposition of the UPJ in relation to these vessels.
        
        If dismembered pyeloplasty is performed for the presence of crossing vessels, the renal pelvis is first transected circumferentially above the UPJ and the lateral aspect of the proximal ureter is spatulated. The renal pelvis and proximal ureter are then transposed to the opposite side of the crossing vessel and the ureteropelvic anastomosis is then completed with intracorporeal suturing techniques
      - Unlike the flap techniques, only a dismembered pyeloplasty allows complete excision of the anatomically or functionally abnormal UPJ itself
    - Dismembered pyeloplasty is not well suited to UPJO associated with (2):
      1. Lengthy or multiple proximal ureteral strictures
        The spiral flap may be of significant value when both UPJO and a relatively long segment of proximal ureteral narrowing or stricture occur in the same setting
      2. Small, relatively inaccessible intrarenal pelvis
  - Non-dismembered pyeloplasty
    - Examples: Y-V plasty and flap pyeloplasty (Culp)
      - The Foley Y-V-plasty is designed for repair of a UPJ obstruction secondary to a high ureteral insertion.
      - Flap procedures are not appropriate in the setting of crossing vessels and when reduction of redundant renal pelvis is desired
  - The provision of external drainage from the site of surgical repair is absolutely necessary
    - Helps reduce risk of urinoma formation leading to possible disruption of the suture line, scarring, or sepsis
- Post-operative care
  - The Foley catheter is usually removed 24 to 36 hours postoperatively, and the surgical drain is removed before hospital discharge if the drain output remains negligible.
    - If the drain output increases after the Foley catheter removal, the Foley catheter should be replaced for 7 days to eliminate urinary reflux along the stent in the treated ureter and decrease urinary extravasation at the ureteropelvic anastomosis.
  - Ureteral stent is typically removed 4-6 weeks later in an outpatient setting
  - Follow-up including the use of imaging studies such as diuretic renal scan is performed
- Adverse events
  - Late
    - Persistent urinary drainage
      - Common after an unstented pyeloplasty is common, and will often require intervention.
      - When associated with a large blood clot, and likely edema at the anastomosis, the kidney will need early drainage until the bleeding resolves and edema improves.
        In children, this is best managed with a nephrostomy tube, as stent placement in a young infant would likely result in stent occlusion from the renal pelvic blood clot.
      - In the majority of cases not associated with an occlusive blood clot, the leak will resolve spontaneously, so observation is the best approach in the early postoperative period in these patients.
        If the leak is persistent and not associated with a consolidated clot, it would most likely resolve with retrograde stent placement.
    - Recurrent obstruction
      - Most failures from laparoscopic pyeloplasty occur in the first 2 years.
      - Management
        Options (2)
        Repeat pyeloplasty (open surgery has been used as a salvage procedure after failed laparoscopic pyelopasty)
        
        Endoscopic intervention (most patients can be managed

Ureterocalicostomy

Indications (3):
1. UPJO or proximal ureteral stricture is associated with a relatively small intrarenal pelvis
2. To provide completely dependent drainage when the UPJ is associated with rotational anomalies such as horseshoe kidney
3. Salvage technique for failed pyeloplasty

Recurrent obstruction after treatment

An open or laparoscopic approach can be recommended to any patient in whom primary endourologic management has failed, and an endourologic approach in whom an open or laparoscopic repair has failed

Questions

What are the causes of UPJO?
What are the indications for intervention in UPJO?
What are the options for intervention in UPJO?
How long is a stent kept for following pyeloplasty?
When should a ureterocalycostomy be considered?
What are the contraindications to endopyelotomy?
Persistence of which structure results in a retrocaval ureter?
What are the causes of ureteral stricture disease?
What are the management options for ureteral stricture disease?
What are the contraindications to transureterostomy?
What investigations are needed before considering transureteroureterostomy?
What are the contraindications to ileal ureter substitution?
What is the preferred approach (retrograde vs. antegrade) for the endoscopic management of ureteroenteric stricture?
What are the risk factors for failure of endourological management of a ureteroenteric anastamostic stricture?

Answers

What are the causes of UPJO?
1. Congenital SHAVA
  1. True ureteral Stricture
  2. High insertion; found more frequently in the presence of renal ectopia or fusion anomalies
  3. Aberrant vessels (controversy persists). Regardless, the presence of crossing vessels has a detrimental effect on the success rates of endopyelotomy
  4. Kinks or Valves produced by infoldings of the ureteral mucosa and muscularis
  5. Aperistaltic segment
2. Acquired CRIBS
  1. Cancer
  2. Reflux
  3. Ischemia
  4. Benign tumour
  5. Stones
What are the indications for intervention in UPJO?
1. Symptoms
2. Stones
3. Renal insufficiency
4. Infections
5. Causal HTN
What are the options for intervention in UPJO?
1. Observation
2. Diversion (stent or nephrostomy tube)
3. Endoscopic (balloon dilation, endopyelotomy)
4. Pyeloplasty
5. Ureterocalycostomy
How long is a stent kept for following pyeloplasty?
1. 4-6 weeks
When should a ureterocalycostomy be considered?
1. Small renal pelvis
2. Dependent drainage in malrotated/ectopic kidney
3. Failed pyeloplasty
What are the contraindications to endopyelotomy?
1. Stricture > 2cm
2. Active infection
3. Uncontrolled coagulopathy

References

Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 49