SFU Society Guidelines for Managing Hydronephrosis
The Society for Fetal Urology (SFU) recommends a systematic approach to hydronephrosis management based on grading severity, with initial postnatal ultrasound performed 48-72 hours after birth, followed by regular monitoring with repeat ultrasound in 1-6 months depending on severity. 1
Grading and Initial Assessment
The SFU grading system classifies hydronephrosis severity:
- Grade 1-2: Mild hydronephrosis (APRPD <15 mm)
- Grade 3-4: Moderate to severe hydronephrosis (APRPD >15 mm)
Initial evaluation should include:
- Postnatal ultrasound at 48-72 hours after birth
- Earlier imaging for severe bilateral hydronephrosis, bladder abnormalities, or oligohydramnios 1
Follow-up Recommendations
Mild Hydronephrosis (SFU Grade 1-2)
- Follow-up ultrasound in 1-6 months
- No immediate intervention required
- Resolution rate: 64-73% 1
- Monitoring every 3-6 months until resolution
Moderate to Severe Hydronephrosis (SFU Grade 3-4)
- Follow-up ultrasound in 1-3 months initially
- Antibiotic prophylaxis recommended
- Resolution rate: approximately 29% 1
- More frequent monitoring (every 1-3 months initially)
Diagnostic Workup
Voiding Cystourethrography (VCUG)
VCUG is indicated for:
- Bilateral high-grade hydronephrosis
- Duplex kidneys with hydronephrosis
- Ureterocele
- Ureteric dilatation
- Abnormal bladder
- History of febrile UTIs 2, 1
The American College of Radiology notes that approximately 16% of infants with antenatal hydronephrosis will have vesicoureteral reflux (VUR), independent of the degree of hydronephrosis 2.
MAG3 Renal Scan
- Recommended after 2 months of age
- Evaluates renal function and drainage
- Preferred over DTPA for suspected obstruction or impaired renal function 2
- Indications for surgical intervention based on scan results:
- T1/2 >20 minutes on diuretic renal scan
- Decreased renal function (<40% differential function)
- Deteriorating function (>5% change on consecutive scans)
- Worsening drainage on serial imaging 1
Management Approach
Antibiotic Prophylaxis
Recommended for:
- Moderate to severe hydronephrosis
- Confirmed VUR
- Hydroureter
- Abnormal bladder 1
Monitoring Requirements
- Regular kidney ultrasound at least once every 2 years to monitor for dilatation of the urinary tract and/or bladder dysfunction caused by polyuria 2
- More frequent monitoring during the first 2 years of life to identify the 22-35% of cases that will require surgical intervention 1
Surgical Intervention
Indications for surgery include:
- Progressive hydronephrosis
- Declining differential renal function (<40%)
- Recurrent UTIs
- Symptoms (pain, hematuria) 1
Surgical options include:
- Pyeloplasty for ureteropelvic junction obstruction (UPJO)
- Valve ablation for posterior urethral valves (PUV)
- Ureteral reimplantation for severe VUR or obstructive megaureter 1
Multidisciplinary Approach
The SFU guidelines align with broader recommendations that patients with hydronephrosis should be followed by a multidisciplinary team that includes:
- (Pediatric) nephrologist
- Dietitian
- Psychologist
- Social worker
- Urologist 2
Special Considerations
- Bilateral hydronephrosis: Research supports an initial nonoperative approach even in severe cases, with 65-78% of kidneys improving spontaneously without surgery 1
- Pregnancy-related hydronephrosis: Occurs in 70-90% of pregnant patients, typically asymmetrically prominent on the right. For imaging during pregnancy, ultrasound or MRU without contrast is preferred to avoid ionizing radiation and gadolinium contrast 2
The negative predictive value of a normal postnatal ultrasound is 98.9% for babies who subsequently present with UTI before their first birthday, highlighting the importance of proper initial assessment 1.