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):
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.
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
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):
Decompression (ureteral stent or nephrostomy tube)
Endourological procedures (balloon dilation or endopyelotomy)
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
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):
>2 cm of obstruction
Untreated UTI
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
Bleeding requiring transfusion
Urinary leak
Drainage-related complications
Hydropneumothorax
Risk is increased if upper pole access is used
Late
Recurrent obstruction
Options if percutaneous endopyelotomy fails:
Retrograde endopyelotomy
Repeat percutaneous endopyelotomy
Laparoscopic, robotic, or open operative intervention
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):
Untreated UTI
Uncorrected coagulopathy
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):
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
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
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