What is the clinical significance of a CT scan showing multiple intrarenal calculi (kidney stones) with staghorn formation, bilateral renal stones measuring 2.5 cm and 2.4 cm, left renal sinus cysts, and a decompressed urinary bladder, without obstructing nephrolithiasis (kidney stone obstruction) or hydronephrosis (kidney swelling)?

Clinical Significance of Bilateral Staghorn Calculi Without Obstruction

This CT scan reveals bilateral staghorn calculi requiring urgent urologic referral for surgical intervention, as staghorn stones carry significant morbidity and mortality risk even without acute obstruction, and the large left renal sinus cyst requires additional evaluation to rule out mass effect or other complications. 1, 2

Understanding the Key Findings

Staghorn Calculi (2.5 cm right, 2.4 cm left)

• Staghorn stones are large branching calculi that fill the renal pelvis and calyces, representing a serious disease entity requiring aggressive management 1, 2
• Most staghorn stones contain struvite (magnesium ammonium phosphate) associated with urease-producing bacterial infections, though approximately one-third are non-struvite stones that grow extremely large and may have sterile urine 1, 3
• Conservative management of staghorn stones carries a 28% mortality rate over 10 years and 36% risk of significant renal impairment, making prompt surgical treatment mandatory 2

Absence of Obstruction and Hydronephrosis

• The lack of hydronephrosis does NOT eliminate the need for intervention or indicate a benign course 4, 5
• While absence of hydronephrosis combined with absence of hematuria has a 96.4% negative predictive value for acute ureteral obstruction, this applies to acute obstructing stones, not chronic staghorn calculi 6, 4, 5
• Non-obstructing renal stones can still cause symptoms in 7-77% of cases even without obstruction 4
• The absence of acute obstruction in staghorn disease often reflects chronic adaptation rather than benign pathology 1, 2

Left Renal Sinus Cysts (>5 cm)

• The large renal sinus cyst requires differentiation from other pathology and assessment for mass effect on the collecting system 7
• This finding may complicate surgical planning and requires careful preoperative evaluation 1

Decompressed Bladder

• This indicates the bladder was empty at time of imaging, which is a technical observation without specific clinical significance in this context 6

Required Clinical Actions

Immediate Management

• Obtain complete urine culture and sensitivity testing, as infection eradication is a primary treatment goal for staghorn stones 1, 2
• Check renal function (creatinine, eGFR) to assess baseline kidney function before intervention 1, 2
• Review all prior urine cultures to identify urease-producing organisms (Proteus, Klebsiella, Pseudomonas) 1

Urgent Urology Referral

• Percutaneous nephrolithotomy (PCNL) is the gold standard first-line treatment for staghorn stones and should be planned expeditiously 1, 2
• Bilateral disease may require staged procedures 1, 2
• The large left renal sinus cyst must be evaluated by urology to determine if it affects surgical approach 1

Preoperative Planning Considerations

• Stone composition analysis is essential—struvite stones are softer and infection-related, while non-struvite stones are harder and may have sterile urine 1, 3
• Consider 3D CT reconstruction for precise surgical planning, particularly for mapping stone branches and determining number of percutaneous access ports needed 8
• Tranexamic acid may be used perioperatively to reduce bleeding risk 1

Critical Pitfalls to Avoid

Do Not Delay Treatment

• The absence of symptoms or obstruction does NOT justify conservative management—staghorn stones require definitive surgical treatment regardless of symptom status 2
• Waiting for symptoms to develop increases risk of irreversible renal damage, sepsis, and mortality 2

Do Not Underestimate Stone Burden

• CT can occasionally overestimate stone size due to motion artifact, so correlation with plain radiography (KUB) and intraoperative imaging is important for surgical planning 9
• The bilateral nature of disease increases complexity and risk 1, 3

Do Not Overlook Infection Risk

• Even with sterile urine currently, staghorn stones create a nidus for recurrent infection 1, 2
• Long-term or short-term antibiotic therapy is recommended, and regular urine cultures should be performed postoperatively 1

Do Not Ignore the Renal Sinus Cyst

• A 5+ cm renal sinus cyst is unusually large and requires evaluation to exclude other pathology or complications 7
• This may affect surgical approach and outcomes 1

Long-Term Management Goals

• Achieve stone-free status, eradicate infection, and prevent recurrence through regular imaging surveillance and metabolic evaluation 1, 2
• Postoperative imaging with CT is most accurate for confirming stone-free status, though ultrasound combined with KUB is an alternative to reduce radiation exposure 1
• Regular follow-up imaging and urine cultures are mandatory to detect recurrence early 1