What is the recommended management for a patient with moderate left hydronephrosis and a left kidney stone?

Management of Moderate Left Hydronephrosis with Left Kidney Stone

The patient requires urgent CT abdomen and pelvis with IV contrast to determine the cause of obstruction, followed by urological consultation for definitive stone management, with the specific intervention determined by stone size, location, and presence of infection. 1

Immediate Diagnostic Workup

Required Laboratory Tests

• Obtain urinalysis and urine culture immediately to rule out infection—the combination of obstruction and infection constitutes a urological emergency requiring urgent decompression 1
• Check serum creatinine, BUN, and electrolytes to assess renal function, particularly given the loss of corticomedullary differentiation in the left kidney 1
• Obtain CBC with differential to evaluate for leukocytosis suggesting infection 1

Essential Imaging

• CT urography (CTU) or CT abdomen/pelvis with IV contrast is the gold standard to define the exact location and size of the obstructing stone, assess degree of obstruction, and identify the cause of hydronephrosis 1
• The 0.6 cm stone in the middle calyceal group may not be the primary cause of the moderate hydronephrosis—CT will identify any ureteral stone or other obstructing pathology 1
• CT provides critical information about stone density (Hounsfield units), which predicts treatment success and guides intervention choice 1

Risk Stratification and Urgent Intervention Criteria

Immediate Urological Referral Required If:

• Fever, leukocytosis, or positive urine culture with obstruction present—this represents obstructive pyelonephritis/urosepsis requiring emergent decompression within hours 1
• Intractable pain despite adequate analgesia 2
• Acute kidney injury or rising creatinine 3
• Solitary kidney (not applicable here, but the left kidney shows concerning loss of corticomedullary differentiation) 1

If Infection is Present:

• The collecting system must be urgently drained with either retrograde ureteral stent or percutaneous nephrostomy (PCN) before definitive stone treatment 1
• Abort any stone removal procedure if purulent urine is encountered, establish drainage, obtain culture, and continue broad-spectrum antibiotics 1
• Retrograde ureteral stenting is generally preferred over PCN due to shorter hospital stays and fewer subsequent interventions, though PCN may be preferred if patient is high-risk for anesthesia or has pyonephrosis requiring larger tube decompression 1

Definitive Stone Management Strategy

For the 0.6 cm (6 mm) Calyceal Stone:

• If this stone is causing the obstruction and patient is symptomatic, offer ureteroscopy (URS) or shock wave lithotripsy (SWL) as first-line options 1
• For stones ≤10 mm in non-lower pole locations, both URS and SWL have acceptable stone-free rates, though URS has lower likelihood of requiring repeat procedures 1
• The presence of moderate hydronephrosis indicates this stone is causing significant obstruction, which increases risk of stone passage failure and shifts management toward active intervention rather than observation 3

If Additional Ureteral Stone is Found on CT:

• For ureteral stones <10 mm without infection, medical expulsive therapy with alpha-blockers can be considered if symptoms are controlled 1, 3
• However, patients with moderate to severe hydronephrosis are at higher risk of stone passage failure and require closer monitoring with repeat imaging 1, 3
• If stone does not pass within 28 days or symptoms worsen, urological intervention is required 3

Special Considerations for This Patient:

• The loss of corticomedullary differentiation in the left kidney suggests chronic changes, possibly from longstanding obstruction or recurrent infections 1
• The right kidney shows hypertrophy of columns of Bertin and calcifications but no obstruction—this kidney will maintain function during left-sided intervention 1
• Stone analysis should be sent to guide metabolic workup and prevention strategies 1

Critical Pitfalls to Avoid

• Do not assume the visualized 6 mm calyceal stone is the sole cause of moderate hydronephrosis—a ureteral stone may be present and only CT with contrast will definitively identify it 1
• Do not delay urological referral if any signs of infection are present—untreated bacteriuria with obstruction can rapidly progress to urosepsis with high morbidity and mortality 1, 3
• Do not use ultrasound alone for follow-up—it has limited sensitivity for detecting stones, particularly smaller stones or those in non-dilated systems, with negative predictive value of only 65% 2
• Do not offer SWL as first-line therapy if stone burden exceeds 10 mm in lower pole location or 20 mm total burden—success rates are significantly reduced 1

Follow-Up Protocol

• Repeat imaging is necessary when symptoms change or if stone passage is suspected but needs confirmation 2
• If conservative management is attempted, periodic imaging to monitor stone position and assess hydronephrosis progression is required 3
• Use the least radiation-intensive method appropriate for clinical scenario—consider ultrasound for follow-up when appropriate to reduce cumulative radiation exposure 2
• Urological follow-up within 7 days to determine need for intervention, assess for alternative diagnoses, and evaluate risk of recurrent episodes 2