From the Guidelines
Yes, a small non-obstructive calculus in the right lower pole calyx measuring 5 x 4 mm with a Hounsfield unit (HF) of 500 that remains unchanged from previous imaging is indicated for Extracorporeal Shock Wave Lithotripsy (ESWL) treatment. According to the American Urological Association/Endourological Society guideline, part II, clinicians may offer SWL or URS for symptomatic patients with a total non-lower pole renal stone burden ≤ 20 mm 1. Since the stone in question is located in the lower pole calyx and measures 5 x 4 mm, which is well below the 20 mm threshold, ESWL is a suitable option. The guideline also states that clinicians should offer SWL or URS to patients with symptomatic ≤10 mm lower pole renal stones 1, which further supports the use of ESWL for this patient. Key considerations for ESWL include:
- Stone size and location: The 5 x 4 mm stone in the lower pole calyx is suitable for ESWL.
- Stone composition: The high Hounsfield unit value of 500 suggests the stone is likely composed of calcium, which responds well to shock wave therapy.
- Patient symptoms and overall health: The patient's symptoms and medical history should be taken into account when deciding on ESWL. The procedure typically takes 30-60 minutes and is often performed on an outpatient basis. Patients should expect to drink plenty of fluids afterward to help flush out stone fragments and may need pain medication for discomfort during fragment passage. Follow-up imaging will be necessary to confirm complete stone clearance after treatment.
From the Research
Stone Size and Treatment Options
- The stone in question is 5 x 4 mm, which is smaller than 1 cm in diameter.
- According to 2, lower pole stones smaller than 1 cm in diameter can be managed with observation, shock wave lithotripsy, or ureteroscopy.
Effectiveness of ESWL for Small Stones
- 3 suggests that ESWL is an effective noninvasive procedure for lower caliceal stones less than 2 cm in diameter.
- 4 states that ESWL may have a lower three-month treatment success rate than PCNL or RIRS, but the evidence on QoL outcomes and complication rates is uncertain.
- 5 found that PCNL had the highest stone-free rates, regardless of stone size, but ESWL may be suitable for smaller stones.
Indications for ESWL
- 3 recommends ESWL as the method of choice for lower caliceal stones less than 2 cm in diameter.
- 2 suggests that shock wave lithotripsy may be preferable for lower pole stones smaller than 1 cm in diameter due to more favorable secondary outcomes.
- Given the small size of the stone (5 x 4 mm), ESWL may be a suitable treatment option, as indicated by 3, 2, and 4.