What are the implications of a 9 mm non-obstructing left renal calculus (kidney stone)?

From the Guidelines

A 9 mm nonobstructing left renal calculus can be managed with active surveillance, as recommended by the EAU guidelines for stones up to 15 mm 1.

Key Considerations

• The stone is nonobstructing, which reduces the urgency for immediate intervention.
• The size of the stone is 9 mm, which is below the 15 mm threshold for active surveillance according to the EAU guidelines.
• Active surveillance involves regular follow-up imaging to monitor the stone's size and position, as well as the patient's symptoms.

Management Approach

• Active surveillance is the recommended approach for asymptomatic, non-obstructing caliceal stones up to 15 mm 1.
• Patients should be educated on the signs and symptoms of obstruction or infection, such as fever, severe pain, nausea/vomiting, or decreased urine output, and seek immediate medical attention if these occur.
• Dietary modifications, including reduced sodium, limited animal protein, and moderate calcium intake, can help prevent future stone formation.
• If the stone grows, becomes symptomatic, or is associated with infection, surgical treatment may be necessary, with options including extracorporeal shock wave lithotripsy (ESWL), ureteroscopy with laser lithotripsy, or percutaneous nephrolithotomy (PCNL), depending on the stone's size and location 1.

From the Research

Diagnosis and Treatment of 9 mm Nonobstructing Left Renal Calculus

• The diagnosis of renal calculi can be made using various imaging modalities, including conventional radiography, intravenous urography, ultrasound, magnetic resonance urography, and computed tomography (CT) scans 2.
• CT scans are considered the gold standard for diagnosing renal calculi, but ultrasound is recommended as the initial imaging modality for suspected renal colic in pregnant women and children 2.
• The treatment of renal calculi depends on the size, location, and composition of the stone, as well as the patient's overall health 3, 4.

Treatment Options for Lower-Pole Renal Stones

• Extracorporeal shock wave lithotripsy (ESWL) is a common treatment option for lower-pole renal stones, but its effectiveness depends on the size and composition of the stone 3, 4.
• Percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) are also effective treatment options for lower-pole renal stones, especially for larger stones (>10 mm) 4.
• The success rate of ESWL is lower for stones with a higher attenuation value on CT scans (>1000 Hounsfield units) 5.

Predicting Successful Fragmentation of Renal Calculi

• The attenuation value of renal calculi on CT scans can help predict the success of ESWL treatment 5.
• Stones with a lower attenuation value (<500 Hounsfield units) are more likely to fragment successfully with ESWL, while stones with a higher attenuation value (>1000 Hounsfield units) may require more shock waves or alternative treatment options 5.

Follow-Up and Monitoring

• Post-treatment imaging is recommended to ensure complete fragmentation and stone clearance 2.
• Plain radiography is suggested for the follow-up of radiopaque stones, while ultrasound and limited IVU may be reserved for the follow-up of radiolucent stones to minimize cumulative radiation exposure 2.