Management of Severe Hydronephrosis
Severe hydronephrosis requires urgent decompression, particularly when accompanied by infection or sepsis, with options including percutaneous nephrostomy (PCN) or retrograde ureteral stenting based on the clinical situation and technical feasibility. 1
Initial Evaluation
- Ultrasound of kidneys and bladder is the recommended first imaging study for patients with suspected hydronephrosis to assess severity and identify potential causes 2
- Severity is classified using the Society for Fetal Urology (SFU) grading system, with grade 3-4 considered severe, or by measuring the anteroposterior renal pelvis diameter (APRPD) with >15 mm indicating severe hydronephrosis 2
- Laboratory assessment should include renal function tests and urinalysis to check for infection 1, 3
- Progressive dilation of the upper urinary tract can lead to acute kidney injury and permanent nephron loss if not corrected promptly 3
Diagnostic Workup
- For severe hydronephrosis, additional imaging is required to determine the cause and guide management 2
- Fluoroscopic voiding cystourethrography (VCUG) is indicated for male patients with moderate to severe hydronephrosis to exclude posterior urethral valves (PUV) and vesicoureteral reflux (VUR) 2
- MAG3 renal scan is preferred over DTPA for evaluating renal function and drainage, particularly in patients with suspected obstruction or impaired renal function 2
- Diuretic renography with MAG3 is the standard for confirming functional obstruction and differentiating true obstruction from non-obstructive dilation 1
Urgent Management
- Urgent decompression is required when severe hydronephrosis is accompanied by infection/sepsis, acute kidney injury, or significant pain 1, 4
- Decompression options include:
- The choice between PCN and retrograde stenting should be based on technical feasibility and clinical circumstances 1, 4
Management Based on Etiology
Ureteropelvic Junction Obstruction (UPJO)
- Surgical intervention is indicated when there is evidence of obstruction based on T1/2 of time activity curve (>20 minutes), decreased renal function (<40% differential function), deteriorating function (>5% change on consecutive renal scans), or worsening drainage on serial imaging 2
Posterior Urethral Valves (PUV)
- When PUV is diagnosed, immediate referral to urology is needed 2
- In male infants with suspected PUV, bladder catheterization at birth to decompress the urinary tract is recommended 2
Vesicoureteral Reflux (VUR)
- VUR accounts for approximately 30% of urinary tract abnormalities in patients with hydronephrosis 2
- Higher grades of hydronephrosis correlate with increased severity of VUR 2
Urolithiasis
- Severe hydronephrosis in the setting of ureteral stones has higher rates of passage failure (43%) compared to moderate (28%), mild (20%), or absent (15%) hydronephrosis 5
- Patients with severe hydronephrosis due to stones warrant definitive imaging and urological referral 5
Follow-up Management
- Regular monitoring of renal function and imaging follow-up are essential 1
- For persistent hydronephrosis, ultrasound monitoring should be performed at least once every 2 years to assess for progression 6, 1
- Definitive correction of the underlying cause should follow initial decompression 1
- MAG3 renal scan can be used to monitor function over time, with a decrease in differential renal function often serving as an indicator for intervention 2
Special Considerations
- In bilateral hydronephrosis, the risk of acute kidney injury is higher, requiring more urgent intervention 1
- MR urography (MRU) may be considered in cases with atypical urinary tract anatomy, such as duplicated collecting systems or renal dysgenesis, though it's not routinely recommended in the initial workup 2
- Prophylactic antibiotics should be considered in patients with severe hydronephrosis to prevent urinary tract infections 2