What is the management plan for a patient with right renal agenesis, left gross hydronephrosis, and a dysmorphic face?

Management of Right Renal Agenesis with Left Gross Hydronephrosis and Dysmorphic Facies

This patient requires urgent comprehensive genetic evaluation, immediate functional assessment of the solitary left kidney with MAG3 renal scan, and prompt urological intervention if obstruction is confirmed, as the combination of dysmorphic features with renal anomalies suggests an underlying genetic syndrome that demands multidisciplinary management to prevent irreversible loss of the only functioning kidney. 1, 2

Immediate Diagnostic Workup

Genetic and Syndromic Evaluation

• Perform whole-exome sequencing immediately to identify potential genetic syndromes, particularly DREAM-PL syndrome (CTU2 gene mutations), 22q11.2 deletion syndrome, or other CAKUT-associated conditions, as dysmorphic facies combined with renal agenesis strongly suggests a syndromic diagnosis 1, 3
• Document specific dysmorphic features: hypertelorism, epicanthic folds, ear position and morphology, nasal configuration, micrognathia, and any skeletal abnormalities 1
• Conduct ophthalmological examination, hearing assessment, and cardiac ultrasound to identify associated anomalies common in genetic syndromes 1
• Perform genital examination to assess for ambiguous genitalia or cryptorchidism, which may indicate DREAM-PL or related syndromes 1, 3

Renal Function Assessment

• Obtain MAG3 diuretic renal scan as the standard of care to differentiate true obstructive hydronephrosis from non-obstructive dilation; T1/2 >20 minutes indicates obstruction requiring intervention 2
• Measure serum creatinine, BUN, and calculate eGFR to assess baseline renal function in the solitary kidney 1, 4
• Perform renal ultrasound to grade hydronephrosis severity, assess for nephrocalcinosis, and evaluate kidney echogenicity and size 1
• CT urography with IV contrast provides definitive anatomical detail if ultrasound findings are equivocal, though radiation exposure must be considered 1, 2

Additional Baseline Studies

• Complete blood count, electrolytes (sodium, chloride, potassium, magnesium), albumin, calcium, phosphate, alkaline phosphatase, PTH, and 25(OH) vitamin D3 1, 4
• Urinalysis and urine culture to exclude infection, which would necessitate immediate decompression 1, 2
• Blood pressure measurement, as renovascular hypertension may develop with renal anomalies 1

Urgent Intervention Criteria

Immediate urological decompression via percutaneous nephrostomy or retrograde ureteral stenting is mandatory if any of the following are present: 1, 2

• Urinary tract infection or sepsis
• Acute kidney injury (rising creatinine)
• Significant flank pain
• MAG3 scan showing obstructive pattern (T1/2 >20 minutes)

Surgical pyeloplasty is indicated when: 2, 5

• MAG3 scan demonstrates T1/2 >20 minutes with obstructive drainage pattern
• Differential renal function <40% (though with solitary kidney, absolute function matters more)
• Grade IV hydronephrosis with deteriorating function
• Recurrent urinary tract infections despite prophylaxis

Conservative Management Protocol (If Non-Obstructive)

Monitoring Schedule

• Serial ultrasound every 3-6 months initially, then every 6-12 months if stable, to detect progression requiring intervention 4, 2, 5
• Repeat MAG3 renal scan every 6-12 months; >5% decrease in differential function serves as intervention threshold 2
• Monitor growth parameters (height, weight, head circumference if <2 years) at each visit 1
• Assess blood pressure at every visit due to risk of renovascular hypertension 1, 4

Prophylactic Measures

• Antibiotic prophylaxis should be considered given severe hydronephrosis in a solitary kidney to prevent UTIs that could precipitate acute kidney injury 2
• Avoid ACE inhibitors or ARBs as they can precipitate acute kidney injury in obstructive uropathy by reducing glomerular filtration pressure 2
• Ensure adequate hydration and nutrition with renal dietician consultation 1, 4

Multidisciplinary Team Involvement

Immediate referrals required: 1

• Pediatric nephrology for ongoing renal function management
• Pediatric urology for surgical planning if obstruction confirmed
• Medical genetics for syndrome diagnosis and family counseling
• Pediatric cardiology if cardiac anomalies detected on screening
• Developmental pediatrics for neurodevelopmental assessment given dysmorphic features

Critical Pitfalls to Avoid

• Never assume hydronephrosis is physiologic in a solitary kidney—functional assessment with MAG3 is mandatory to prevent irreversible nephron loss 2, 5
• Do not delay genetic testing—early syndrome diagnosis impacts management of associated anomalies and provides prognostic information 1, 3
• Avoid nephrotoxic medications including NSAIDs, aminoglycosides, and contrast agents unless absolutely necessary 4
• Do not miss contralateral renal anomalies—approximately 26-75% of patients with unilateral renal agenesis have associated urogenital abnormalities 1
• Recognize that apparent "renal agenesis" may represent involuted multicystic dysplastic kidney, which has different prognostic implications 6

Long-Term Considerations

• Early referral to transplant center is appropriate given solitary kidney with severe hydronephrosis, as progression to end-stage renal disease is possible 1
• Monitor for chronic kidney disease development with serial creatinine and microalbuminuria assessment 4
• Assess quality of life using age-appropriate scales every 2 years from age 5 4
• Provide genetic counseling regarding recurrence risk in future pregnancies, particularly if autosomal recessive syndrome identified 3, 7