Initial Management Plan for Suspected Kidney Stones
The initial management of suspected kidney stones should include a non-contrast CT scan as the first-line imaging modality, assessment of serum electrolytes, creatinine and BUN, urinalysis with microscopic evaluation, and appropriate pain management with NSAIDs as first-line therapy. 1, 2, 3
Diagnostic Evaluation
Initial Laboratory Testing
- Obtain serum chemistries including electrolytes, calcium, creatinine, and BUN to identify underlying medical conditions and assess renal function 1
- Perform urinalysis with both dipstick and microscopic evaluation to assess urine pH, indicators of infection, and identify crystals that may indicate stone type 1
- Collect urine culture if urinalysis suggests infection or if patient has history of recurrent UTIs 1
Imaging
- Non-contrast CT scan is the gold standard for initial evaluation of suspected kidney stones 2, 4
- Renal ultrasonography can be used as an alternative first-line imaging modality, particularly in pregnant patients, though it has lower sensitivity (45%) and specificity (88%) compared to CT 2, 4
- In patients with complex stones or anatomy, additional contrast imaging may be needed for better definition of the collecting system and ureteral anatomy 5
Pain Management
- NSAIDs are the first-line choice for pain management in patients with kidney stones 2
- Adequate hydration should be maintained, but forced hydration has not been shown to accelerate stone passage 5
Medical Expulsive Therapy (MET)
- MET is recommended as first-line therapy for uncomplicated distal ureteral stones ≤10 mm in diameter 2
- MET can facilitate stone passage and reduce the need for surgical intervention 2
Metabolic Evaluation
- For first-time stone formers with low risk of recurrence, a limited evaluation including serum chemistries and urinalysis may be sufficient 1, 6
- More comprehensive metabolic evaluation with 24-hour urine collection is recommended for:
- 24-hour urine collection should analyze at minimum: total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 5, 1
Surgical Intervention Considerations
- If stones fail to pass with conservative management or MET, consider surgical intervention based on:
- Surgical options include:
- Extracorporeal shock wave lithotripsy (SWL)
- Ureteroscopy (URS)
- Percutaneous nephrolithotomy (PCNL) 2
- Open/laparoscopic/robotic surgery should not be offered as first-line therapy except in rare cases with anatomic abnormalities, large/complex stones, or those requiring reconstruction 5
Special Considerations
- If purulent urine is encountered during endoscopic intervention, abort the procedure, establish appropriate drainage, continue antibiotic therapy, and obtain a urine culture 5
- Stone material should be sent for analysis when available to guide future prevention strategies 5, 1
- Antimicrobial prophylaxis should be administered prior to stone intervention based on prior urine culture results and local antibiogram 5
Prevention of Recurrence
- Recommend fluid intake that will achieve a urine volume of at least 2.5 liters daily 5
- For patients with calcium stones and high urinary calcium, limit sodium intake and consume 1,000-1,200 mg per day of dietary calcium 5
- For patients with calcium oxalate stones and high urinary oxalate, limit intake of oxalate-rich foods while maintaining normal calcium consumption 5
Common Pitfalls to Avoid
- Failing to obtain appropriate imaging to confirm diagnosis and assess stone burden 1, 3
- Overlooking signs of infection or sepsis, which require immediate intervention 5
- Not sending stone material for analysis when available 5
- Inadequate pain management during acute episodes 2
- Recommending low calcium diets, which can paradoxically increase stone formation 5