What is the management approach for a patient with two 7mm non-obstructing stones in the left kidney and no hydronephrosis?

Management of Two 7mm Non-Obstructing Renal Stones

Active surveillance with follow-up imaging is the recommended initial approach for these asymptomatic, non-obstructing 7mm renal stones, as they fall within the acceptable size range for observation (up to 15mm per EAU guidelines). 1

Initial Management Strategy

Observation is appropriate for asymptomatic, non-obstructing caliceal stones of this size, with the following considerations:

• Both AUA/ES and EAU guidelines support active surveillance for asymptomatic, non-obstructing renal stones 1
• EAU guidelines specifically state that active surveillance is acceptable for stones up to 15mm 1
• Your patient's 7mm stones fall well within this threshold 1

Follow-Up Imaging Requirements

Regular imaging surveillance is mandatory to monitor for complications:

• Follow-up imaging should be obtained to monitor for stone growth, development of obstruction, or symptoms 1
• Natural history data shows that approximately 28% of asymptomatic non-obstructing stones become symptomatic over 3+ years of follow-up 2
• Importantly, 2-3% of initially asymptomatic stones can cause silent obstruction requiring intervention, making regular imaging critical to prevent renal loss 2

Indications for Intervention

Surgical treatment should be offered if any of the following develop:

• Stone growth on serial imaging 1
• Development of symptoms (renal colic, pain) 1
• Associated infection 1
• Development of obstruction or hydronephrosis 1
• Specific vocational or lifestyle reasons (e.g., pilots, military personnel, remote workers) 1

Surgical Options If Intervention Becomes Necessary

For 7mm renal stones requiring treatment, flexible ureteroscopy (fURS) or shock wave lithotripsy (SWL) are first-line options:

• For stones <20mm in the renal pelvis or upper/middle calyx, both fURS and SWL are recommended first-line treatments 1
• Stone location matters: if these are lower pole stones, fURS or SWL remain appropriate for stones <10mm 1
• PCNL is generally reserved for stones >20mm 1

Stone Location Considerations

The specific location of these stones within the kidney affects prognosis:

• Upper pole/mid renal stones are more likely to become symptomatic (40.6%) and pass spontaneously (14.5%) compared to lower pole stones (24.3% symptomatic, 2.9% passage rate) 2
• Lower pole stones are significantly less likely to cause symptoms or pass spontaneously 2

Metabolic Evaluation

Consider obtaining a 24-hour urine collection for stone risk factors to guide preventive strategies:

• This should be done to assess metabolic abnormalities that could be modified to prevent stone growth or new stone formation 1
• Increased fluid intake should be recommended to all patients to reduce recurrence risk 3

Key Pitfalls to Avoid

• Do not ignore these stones completely: While observation is appropriate, lack of follow-up imaging can miss silent obstruction that may lead to renal damage 2
• Do not rush to surgery: These stones do not require immediate intervention in the absence of symptoms, infection, or obstruction 1
• Do not assume all stones will pass: At 7mm, spontaneous passage is unlikely (only 7% in natural history studies), particularly for lower pole stones 2