What is the best next step for a 42-year-old woman with flank pain, nausea, and a 12 mm kidney stone?

Management of 12 mm Kidney Stone with Flank Pain and Nausea

For a 42-year-old woman with a 12 mm kidney stone causing flank pain and nausea, ureteroscopy (URS) is the recommended first-line surgical intervention, with percutaneous nephrolithotomy (PCNL) as an alternative option depending on stone location. 1

Immediate Symptom Management

Pain control should be initiated immediately with NSAIDs as first-line therapy:

• Diclofenac, ibuprofen, or metamizole are preferred over opioids for renal colic 1
• NSAIDs reduce the need for additional analgesia compared to opioids and have fewer side effects, particularly less vomiting (6% vs 20% with opioids) 2
• Use the lowest effective dose due to cardiovascular and gastrointestinal risks 1
• Opioids (hydromorphine, pentazocine, or tramadol—NOT pethidine) should be reserved as second-line agents 1
• Anti-emetics should be administered for nausea control 1

Critical Assessment Before Definitive Treatment

Evaluate for complications requiring urgent intervention:

• Check for signs of infection (fever, elevated CRP, white blood cell count) 1
• Assess renal function (serum creatinine) and check for anuria or bilateral obstruction 1
• If sepsis and/or anuria are present, urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory BEFORE definitive stone treatment 1
• Obtain urine culture before any intervention 1

Definitive Surgical Management

A 12 mm stone will NOT pass spontaneously and requires surgical intervention:

Stone Location Determines Approach:

For renal pelvis or upper/middle calyx stones (10-20 mm):

• Flexible ureteroscopy (fURS) is first-line 1
• PCNL is an alternative option for stones 10-20 mm 1
• Shock wave lithotripsy (SWL) is NOT recommended as first-line for stones >10 mm 1

For lower pole stones (10-20 mm):

• fURS and PCNL are both recommended options 1
• PCNL may be preferred for lower pole stones >15 mm 1

For ureteral stones >10 mm (if stone has migrated):

• URS is the recommended first-line treatment regardless of location 1

Pre-Procedural Considerations

Before surgical intervention:

• Obtain urine microscopy and culture to exclude or treat UTI before stone removal 1
• Administer single-dose perioperative antibiotic prophylaxis 1
• Routine pre-stenting is NOT recommended but may improve outcomes for renal stones 1
• Use a safety guidewire during ureteroscopy 1

Post-Procedural Management

After ureteroscopic treatment:

• Routine ureteral stent placement is NOT required postoperatively 1
• If a stent is placed, prescribe alpha-blockers to reduce stent-related discomfort 1
• Send stone for compositional analysis (recommended for all first-time stone formers) 1

Metabolic Workup

Obtain baseline laboratory evaluation:

• Serum: creatinine, uric acid, ionized calcium, sodium, potassium, CRP 1
• Urinalysis with dipstick 1
• More extensive metabolic evaluation is reserved for high-risk patients (recurrent stones, bilateral disease, strong family history) 1

Common Pitfalls to Avoid

• Do NOT attempt conservative management or medical expulsive therapy for a 12 mm stone—stones >10 mm have extremely low spontaneous passage rates and require intervention 1, 3
• Do NOT delay intervention if infection is present—sepsis with obstruction requires immediate decompression, with definitive stone treatment delayed until infection resolves 1
• Do NOT use pethidine if opioids are needed—it has higher vomiting rates and greater need for rescue analgesia 1
• Do NOT perform definitive stone treatment without first obtaining urine culture 1