What is the treatment for hydronephrosis?

Treatment of Hydronephrosis

The treatment of hydronephrosis depends critically on whether obstruction is present, the underlying etiology, and whether the patient has bilateral disease, infection, or acute kidney injury—with urgent decompression via percutaneous nephrostomy or retrograde ureteral stenting required for infected/septic hydronephrosis, bilateral obstruction with renal impairment, or significant pain. 1, 2, 3

Immediate Assessment and Risk Stratification

Critical Urgency Indicators Requiring Immediate Intervention

• Bilateral hydronephrosis demands urgent evaluation regardless of symptom severity or normal creatinine, because both kidneys are simultaneously at risk without contralateral functional reserve, and progressive obstruction causes irreversible nephron loss even when initially asymptomatic 1
• Infected/septic hydronephrosis requires emergent decompression to prevent progression to septic shock and permanent renal damage 2, 4
• Acute kidney injury with obstruction necessitates prompt intervention to preserve renal function 1, 3
• Significant pain refractory to conservative management warrants decompression 2

Key Clinical Pitfall

Upper urinary tract deterioration is often clinically silent and detected incidentally with nonspecific symptoms—normal serum creatinine does not exclude significant obstruction, especially in unilateral disease where contralateral compensation masks dysfunction 5, 1

Diagnostic Algorithm to Guide Treatment

Initial Imaging

• Ultrasound of kidneys and bladder is the first-line imaging study to assess severity and identify potential causes 2
• Severity classification uses Society for Fetal Urology (SFU) grading (grade 3-4 = severe) or anteroposterior renal pelvis diameter (APRPD >15 mm = severe) 2

Functional Assessment

• MAG3 renal scan with diuretic administration is the de facto standard for diagnosing true obstructive uropathy and differentiates functional obstruction from non-obstructive dilation 1, 2, 3
• Obstruction criteria: T1/2 >20 minutes, differential renal function <40%, or deteriorating function (>5% change on consecutive scans) 1, 2

Anatomic/Etiologic Evaluation

• CT urography (CTU) without and with IV contrast provides both morphological and functional information to identify underlying causes including bladder outlet obstruction, pelvic pathology, retroperitoneal processes, or bladder dysfunction 1, 3
• MR urography with IV contrast is preferred if renal impairment develops to avoid nephrotoxic contrast while providing comprehensive evaluation 1
• Fluoroscopic voiding cystourethrography (VCUG) is indicated for male patients with moderate to severe hydronephrosis to exclude posterior urethral valves and vesicoureteral reflux 1, 2

Treatment Algorithm Based on Clinical Presentation

Emergent Decompression (Infection/Sepsis, AKI, Bilateral Obstruction)

Immediate percutaneous nephrostomy (PCN) or retrograde ureteral stenting is indicated when hydronephrosis presents with infection/sepsis, acute kidney injury, or significant pain 1, 2, 3

Choice Between PCN vs Retrograde Stenting

• PCN is preferred in septic patients due to higher success rates and avoidance of instrumentation through infected urine 3, 4
• PCN technical success approaches 100% in dilated collecting systems and 80-90% in non-dilated systems 3
• Retrograde stenting is preferred in stable patients without sepsis 3
• Neither modality shows superiority in effecting decompression and resolution of sepsis based on randomized trials, though complication rates differ (PCN major complications ~4%) 4

Bladder Outlet Obstruction

Bladder catheterization for immediate decompression is necessary, followed by definitive surgical correction of the underlying cause (e.g., prostatic hyperplasia) 1

Posterior Urethral Valves (Male Infants)

Immediate bladder catheterization at birth to decompress the urinary tract, followed by urgent urology referral 2

Ureteropelvic Junction Obstruction (UPJO)

Surgical pyeloplasty is indicated when MAG3 scan demonstrates:

• T1/2 >20 minutes 1, 2
• Differential renal function <40% 1, 2
• Deteriorating function (>5% change on consecutive scans) 1, 2
• Worsening drainage on serial imaging 1

Vesicoureteral Reflux (VUR)

VUR accounts for approximately 30% of urinary tract abnormalities in hydronephrosis, with higher grades correlating with increased severity 2

Special Population Considerations

Neonatal Hydronephrosis

• Initial ultrasound should be delayed 48-72 hours after birth due to low urine production, except in severe bilateral hydronephrosis with bladder abnormalities or oligohydramnios 1
• Follow-up ultrasound at 1-6 months is recommended even with normal initial postnatal imaging, as 45% of initially normal studies show abnormalities on repeat imaging 5
• Routine VCUG is not recommended for antenatal hydronephrosis per 2010 SFU consensus, as most VUR spontaneously resolves and prophylactic antibiotic benefit is unproven 5

Pregnancy

• Asymptomatic hydronephrosis occurs in 70-90% of pregnancies (typically right-sided) due to mechanical obstruction and progesterone effects 5, 1
• Symptomatic hydronephrosis may lead to preterm labor or maternal/fetal death when untreated 1
• MR urography without contrast is preferred to avoid ionizing radiation and gadolinium 1

Bilateral Disease

The bilateral nature eliminates the safety net of contralateral kidney compensation, making prompt treatment essential even with normal serum creatinine 1

Follow-Up Management After Initial Treatment

Monitoring Parameters

• Regular monitoring of renal function with serial creatinine and estimated GFR after initial decompression and definitive treatment 1
• Ultrasound monitoring at least once every 2 years in patients with chronic or persistent hydronephrosis to assess for progression 1, 2, 3
• Repeat MAG3 renal scan to monitor differential function over time, with >5% decrease serving as an indicator for intervention 1, 2

Infection Prevention

Prophylactic antibiotics should be considered in patients with severe hydronephrosis to prevent urinary tract infections 2

Definitive Management

Definitive correction of the underlying cause should follow initial decompression to prevent recurrence and progressive renal damage 1, 3

Common Pitfalls to Avoid

• Do not assume normal creatinine excludes significant obstruction in unilateral disease due to contralateral compensation 5, 1
• Do not delay intervention in bilateral hydronephrosis even with normal labs, as both kidneys are simultaneously at risk 1
• Do not perform bilateral robot-assisted laparoscopic ureteral reimplantation simultaneously due to risk of transient urinary retention 1
• Do not overlook the need for culture-guided antibiotics when draining infected hydronephrosis 6
• Do not skip functional imaging (MAG3) before deciding on surgical intervention, as anatomic dilation does not always indicate functional obstruction 1, 2, 3