Pelviureteric Junction Obstruction: Diagnostic and Treatment Approach
Initial Diagnostic Workup
For suspected pelviureteric junction (PUJ) obstruction, contrast-enhanced CT with delayed urographic phase is the gold standard imaging modality to confirm diagnosis and assess severity. 1
Key Diagnostic Steps:
Ultrasound serves as the initial screening tool to identify hydronephrosis and assess renal parenchymal thickness, particularly useful in pediatric patients and pregnant women to minimize radiation exposure 1, 2
CT urography with delayed phase (5-minute excretory phase) provides definitive anatomical detail, identifies the level and cause of obstruction, and detects urinary extravasation 1
Diuretic renography (MAG3 or DTPA scan) quantifies split renal function and drainage patterns, essential for determining which patients require intervention versus conservative management 3, 4
Look specifically for anatomical variants including renal malrotation, fusion anomalies, ectopic kidneys, and crossing vessels, as these significantly impact surgical planning 2
Critical Diagnostic Pitfalls:
Passive anterograde bladder filling during CT by clamping the catheter is inadequate and produces high false-negative rates due to insufficient intravesical pressure 1
Always assess for coexisting vesicoureteral reflux with voiding cystourethrography, as 2% of children with reflux have concurrent PUJ obstruction requiring pyeloplasty first, not reimplantation 5
Treatment Algorithm Based on Clinical Presentation
Acute Presentation with Infection/Sepsis:
If the patient presents with fever, leukocytosis, or signs of pyonephrosis, urgent percutaneous nephrostomy (PCN) is mandatory within hours, not days, with immediate broad-spectrum antibiotics. 6
PCN achieves >95% technical success in dilated systems and provides immediate source control 1, 7
Administer preprocedural antibiotics within 60 minutes of drainage, preferably third-generation cephalosporins (ceftazidime) over fluoroquinolones for infected obstructed systems 6
Abort any attempts at retrograde stenting in septic patients—establish drainage first, treat infection, then plan definitive repair 6
Acute Kidney Injury with Obstruction:
For patients with declining renal function (eGFR <15) or bilateral obstruction, urgent decompression via PCN or retrograde ureteral stenting is required. 1, 6
PCN has higher technical success rates (approaching 100%) compared to retrograde stenting (80-90%), particularly when dealing with tight strictures, extrinsic compression, or obstruction >3 cm 1, 7
Retrograde stenting should be attempted first in hemodynamically stable patients without infection, as it avoids PCN-related morbidity 1, 7
If retrograde stenting fails or the patient has infection, proceed immediately to PCN 7, 6
Antenatally Detected/Chronic Asymptomatic PUJ Obstruction:
Conservative non-operative management is safe for patients with good initial renal function (>40% split function) and stable ultrasound findings. 3, 4
71% of unilateral cases with good function remain stable without surgery over long-term follow-up 3
Monitor with serial ultrasound and renography every 3-6 months to detect deterioration early 3, 4
Indications for surgical intervention include:
Definitive Surgical Management:
Once renal function stabilizes and infection clears, pyeloplasty (open, laparoscopic, or robotic) is the definitive treatment for symptomatic or functionally significant PUJ obstruction. 6, 2
Pyeloplasty preserves good renal function in nearly all cases and may improve moderate function (20-40% split) in select patients 3
Kidneys with poor function (<20%) show minimal recovery despite surgery, so nephrectomy may be more appropriate 3
Retrograde balloon dilation achieves 80% clinical success and 93% renographic improvement as a less invasive alternative to open pyeloplasty, though it is less effective for secondary (post-surgical) obstruction 8
Special Considerations
Bilateral PUJ Obstruction:
Address the worse-functioning kidney first if staged procedures are needed 5
Both kidneys typically remain stable with conservative management if initial function is preserved 3
Coexisting Reflux:
Always perform pyeloplasty before ureteral reimplantation when both conditions coexist, as the order is crucial for optimal outcomes 5
Significant PUJ obstruction with mild reflux can mimic severe reflux on imaging—voiding cystography with post-void drainage films and diuretic renography differentiate the two 5
Stent Failure in Chronic PUJ:
If a patient with chronic PUJ obstruction and an existing stent develops acute kidney injury or hematuria, assume stent failure until proven otherwise. 7, 6
Mucous plugging, encrustation, and malposition are common causes of stent dysfunction 7, 6
Routine stent exchange every 3-6 months is mandatory to prevent obstruction and infection in patients with chronic stents 7, 6
PCN is superior to repeat retrograde stenting when dealing with stent failure, particularly with extrinsic compression or tight strictures 7