What is the best course of treatment for a patient with a 4 mm obstructing calculus at the right ureterovesical (ureterovesical junction) junction, moderate to severe right hydronephrosis, and an edematous right kidney, with nonobstructive calculi in both kidneys, likely representing obstructive uropathy and superimposed pyelonephritis?

Management of Obstructing Ureterovesical Junction Calculus with Hydronephrosis and Suspected Pyelonephritis

This patient requires urgent urological consultation for immediate decompression, as an obstructing stone with moderate-to-severe hydronephrosis and suspected superimposed pyelonephritis represents a urological emergency that mandates prompt intervention within hours to prevent urosepsis and irreversible renal damage. 1, 2, 3

Immediate Assessment Priorities

Rule out infected obstructed kidney first, as this constitutes the most life-threatening scenario:

• Check for fever, tachycardia, hypotension, or septic appearance—any of these with obstruction requires emergent percutaneous nephrostomy (PCN) within hours 1, 3
• Obtain urine dipstick and culture immediately; positive urinalysis with obstruction mandates urgent drainage before attempting stone removal 2, 3
• Measure serum creatinine to assess renal function and check inflammatory markers (CRP, WBC) 1
• Document vital signs to exclude shock and systemic infection 3

The edematous kidney appearance on CT strongly suggests either obstructive nephropathy or superimposed infection—both scenarios require urgent intervention rather than conservative management. 1

Treatment Algorithm Based on Infection Status

If Infection is Present (Fever, Positive Urinalysis, Elevated WBC/CRP):

Immediate decompression is mandatory—delay risks progression to urosepsis and potential loss of kidney function. 1, 3, 4

• Either retrograde ureteral stent or percutaneous nephrostomy is acceptable for emergency decompression; randomized trials show no superiority of one method over the other for resolving sepsis in acute obstruction 4
• Start broad-spectrum IV antibiotics immediately after obtaining cultures 2, 4
• PCN may be preferred if the patient is septic or hemodynamically unstable, as it avoids instrumenting through infected urine 4
• Definitive stone treatment must be delayed until infection clears—attempting immediate stone removal in infected systems risks overwhelming bacteremia 4

If No Infection is Present:

Urgent urological intervention is still required because this 4mm stone at the ureterovesical junction with moderate-to-severe hydronephrosis has high risk of passage failure. 2, 3

• Patients with moderate-to-severe hydronephrosis have 97% likelihood of requiring urological intervention regardless of stone size 1
• The presence of hydronephrosis indicates this stone is causing significant obstruction, fundamentally changing the risk-benefit calculation away from conservative management 2
• Do not assume this 4mm stone will pass spontaneously—while stones <5mm typically have high spontaneous passage rates, the presence of moderate-to-severe hydronephrosis indicates this stone is impacted and unlikely to pass 2, 3

Definitive Management Options

Ureteroscopy with laser lithotripsy is the preferred definitive treatment for this distal ureteral stone once infection is excluded or cleared:

• Distal ureteral stones at the ureterovesical junction are highly accessible via ureteroscopy 1
• Stone fragmentation and removal can be accomplished in a single procedure 1
• Double-J stent placement after ureteroscopy ensures drainage while ureter heals 5, 6

Medical expulsive therapy is NOT appropriate in this case despite the 4mm stone size, because:

• Moderate-to-severe hydronephrosis predicts passage failure with high likelihood 1, 2
• The edematous kidney appearance suggests prolonged obstruction or infection, both requiring active intervention 1
• Waiting 28 days for spontaneous passage risks progressive renal damage 2, 3

Critical Pitfalls to Avoid

Do not delay urological referral—this is not a "wait and see" scenario:

• Untreated bacteriuria with obstruction can rapidly progress to urosepsis 2, 3
• Even without infection, prolonged obstruction causes irreversible nephron loss 1
• The 3mm nonobstructing stones in both kidneys indicate this patient is a stone-former requiring metabolic evaluation after acute management 7

Do not rely on absence of fever to rule out infection:

• Pyonephrosis can be difficult to distinguish from hydronephrosis even on CT 8
• The "edematous appearance" described suggests inflammatory changes that warrant treating as potentially infected until proven otherwise 1

Do not assume small stone size equals low risk:

• Even 4mm stones can cause calyceal rupture when located distally and causing high intraluminal pressure 5
• Nearly 11% of symptomatic ureteral stones cause pain without hydronephrosis, but this patient has moderate-to-severe hydronephrosis, placing them in the high-risk category 9

Post-Intervention Management

After successful decompression and stone treatment:

• Maintain ureteral stent for 1-2 weeks to ensure adequate drainage while inflammation resolves 5, 6
• Complete full antibiotic course if infection was present 4
• Perform metabolic evaluation to identify correctable risk factors, as 76% of patients with nonstruvite stones have identifiable metabolic abnormalities 7
• Metabolic intervention significantly reduces recurrence: 17% with treatment versus 55% with observation alone 7
• Follow-up imaging in 6-12 weeks to assess resolution of hydronephrosis and monitor the nonobstructing stones 1