What is the treatment approach for a patient diagnosed with kidney stones via ultrasound who is currently passing them?

Management of Kidney Stones Diagnosed by Ultrasound in a Patient Passing Them

For patients with kidney stones diagnosed by ultrasound who are currently passing them, the primary treatment approach should focus on pain management, hydration, and medical expulsive therapy to facilitate stone passage, with consideration for more invasive interventions if stones fail to pass spontaneously. 1

Initial Management for Patients Passing Kidney Stones

• Ultrasound is an appropriate first-line diagnostic tool for kidney stones, with 45% sensitivity and 94% specificity for ureteral stones, though it may overestimate stone size 1
• Pain management should begin with NSAIDs (diclofenac, ibuprofen, metamizole) as first-line treatment for renal colic, with opioids as second-line when NSAIDs are contraindicated 1
• Increased fluid intake is essential to promote stone passage and should be maintained at 2.5-3.0 L/day to achieve urine output of >2.0-2.5 L/day 2, 3

Medical Expulsive Therapy (MET)

• For stones <10 mm, particularly those in the distal ureter, medical expulsive therapy with alpha-blockers is strongly recommended to facilitate passage 1
• Patients should be informed that alpha-blockers are used off-label for this purpose and counseled about potential side effects 1
• MET is most beneficial for stones >5 mm in the distal ureter, where it significantly increases the likelihood of spontaneous passage 1

Stone Size Considerations

• Stones <10 mm have potential for spontaneous passage with observation and MET, though passage rates decrease with increasing size 4
• For stones <6 mm, observation with adequate hydration and pain control is appropriate initial management 4
• For stones >10 mm, surgical intervention is typically required as spontaneous passage is unlikely 1, 4

Monitoring During Conservative Management

• Patients should be monitored with periodic imaging to assess stone position and evaluate for hydronephrosis 1
• Follow-up ultrasound is appropriate for monitoring, though it may miss stones <3 mm 1
• Patients should be monitored for signs of complications such as infection, obstruction, or worsening pain that may necessitate urgent intervention 1

Indications for Urgent Intervention

• Immediate decompression via percutaneous nephrostomy or ureteral stenting is required for patients with sepsis and/or anuria with an obstructed kidney 1
• Patients with intractable pain, evidence of urinary tract infection, or anatomical abnormalities that may complicate stone passage require urgent urological evaluation 4

Prevention of Recurrence

• After successful stone passage, prevention strategies should be implemented based on stone composition 5
• Increased fluid intake to maintain urine output >2 L/day is the cornerstone of prevention for all stone types 1
• For calcium stones, moderate calcium intake (1000-1200 mg/day), limited sodium (2-5 g/day), and limited animal protein are recommended 2
• For patients with recurrent calcium stones, pharmacologic options include thiazides (RR 0.52), citrates (RR 0.25), or allopurinol (RR 0.59) 1
• Potassium citrate is particularly effective for hypocitraturic calcium nephrolithiasis and uric acid stones by increasing urinary pH and citrate excretion 6

Treatment Options if Stones Fail to Pass

• For stones that fail to pass spontaneously, treatment options include extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), or percutaneous nephrolithotomy (PCNL) 1
• For distal ureteral stones >10 mm, URS is recommended as first-line treatment 4
• For proximal ureteral stones <10 mm, both ESWL and URS are appropriate options 4
• PCNL is typically reserved for larger renal stones and has shown higher stone-free rates compared to other approaches 1

Special Considerations

• In pregnant patients, ultrasound remains the first-line imaging modality, with MRI as second-line and low-dose CT as last resort 1
• Patients with a single kidney, renal insufficiency, or anatomical abnormalities may require more aggressive management 1
• Metabolic evaluation is recommended for high-risk patients (those with family history, recurrent stones, or intestinal disease) 7