Is a 5mm obstructive stone in the distal left ureter with a density of 1033 Hounsfield Units (HU) and associated mild left hydroureteronephrosis a candidate for Extracorporeal Shock Wave Lithotripsy (ESWL)?

ESWL for 5mm Distal Ureteral Stone with High Density (1033 HU)

ESWL is a reasonable first-line treatment option for this 5mm distal ureteral stone, though ureteroscopy may offer superior stone-free rates with a single procedure. 1

Treatment Decision Framework

Stone Characteristics Favoring ESWL

• Stone size <10mm makes ESWL an acceptable option according to the 2007 AUA guidelines, which specifically include distal ureteral stones in this size range as candidates for shock wave lithotripsy 1
• The mild hydroureteronephrosis indicates the stone is causing obstruction but not severe enough to mandate urgent intervention 1

Critical Limitation: Stone Density

• The 1033 HU density is a significant concern - stones with density >1000 HU (particularly calcium oxalate monohydrate) have substantially lower fragmentation rates with ESWL 2
• High-density stones often require multiple ESWL sessions or ultimately fail, necessitating salvage ureteroscopy 3

Comparative Treatment Outcomes

ESWL Performance for Distal Stones

• Stone-free rates for distal ureteral stones <10mm with ESWL range from 84-96% depending on the lithotripter used 4
• Retreatment rates are significantly higher with ESWL (4-14% require additional sessions) compared to ureteroscopy 4, 5
• ESWL has lower complication rates (RR 0.54) and shorter hospital stays compared to ureteroscopy 5

Ureteroscopy Performance

• Ureteroscopy achieves 100% stone-free rates for distal stones in this size range with a single procedure 4
• For stones <10mm, ureteroscopy is more cost-efficient and provides superior outcomes, though it requires general anesthesia and routine stent placement 3
• The 2007 AUA guidelines show ureteroscopy has higher initial success but increased complication rates (particularly ureteral injury at 3% and stricture at 1%) 1

Recommendation Algorithm

ESWL is appropriate if:

• Patient prefers less invasive approach with outpatient treatment under IV sedation 4
• Patient accepts potential need for retreatment (up to 14% chance) 4
• No contraindications to general anesthesia exist for potential salvage ureteroscopy 3

Ureteroscopy should be strongly considered instead if:

• Stone density >1000 HU predicts ESWL failure - this is your case 2
• Patient desires single-procedure definitive treatment 5
• Symptoms are severe or infection is present 1

Critical Pitfalls to Avoid

• Never perform blind basketing (stone extraction without endoscopic visualization) - this carries high risk of ureteral injury and is contraindicated 1
• Do not delay treatment beyond 4-6 weeks if obstruction persists, as this risks irreversible renal damage 6
• Screen for infection before any intervention - untreated bacteriuria with obstruction can lead to urosepsis, particularly with ESWL or endoscopic manipulation 1
• Avoid routine stenting with ESWL as it lowers both fragmentation and stone-free rates 3

Practical Considerations

Given the 1033 HU density, ureteroscopy with laser lithotripsy is likely the superior first-line choice despite ESWL being technically indicated for stone size. The high density substantially increases the probability of ESWL failure, making ureteroscopy more cost-effective overall by avoiding multiple procedures 3. However, if patient factors strongly favor ESWL (inability to tolerate anesthesia, patient preference for less invasive approach), it remains a reasonable option with close follow-up planned for potential retreatment 1, 4.