Kidney Stone Movement from Proximal to Distal Ureter
Yes, kidney stones can and do travel from the proximal ureter to the distal ureter as part of their natural passage through the urinary tract. 1 The 2007 AUA Guideline for Management of Ureteral Calculi clearly recognizes this movement pattern by discussing stone management approaches for stones located in different parts of the ureter (proximal, mid, and distal).
Anatomical Considerations of Stone Movement
Ureteral stones typically follow a predictable path:
- Stones originate in the kidney and enter the ureter at the ureteropelvic junction (UPJ)
- They then travel down the ureter, potentially becoming lodged at anatomical narrowings
- Research shows two main areas where stones commonly become lodged 2:
- The ureteropelvic junction (UPJ)/proximal ureter
- The intramural ureter/ureterovesical junction (UVJ)
Contrary to traditional teaching that suggests three distinct narrowing points (UPJ, iliac vessel crossing, and UVJ), evidence indicates that stones primarily lodge at the proximal and distal ends of the ureter 2.
Factors Affecting Stone Movement
Several factors influence how and whether stones move from proximal to distal ureter:
- Stone size: Smaller stones (<2mm) move more quickly (average 8.2 days) than larger stones (4-6mm, average 22.1 days) 3
- Stone location: Stones in the distal ureter pass more readily than those in the proximal ureter 3
- Side: Interestingly, stones on the right side pass more readily than those on the left 3
- Ureteral peristalsis: Normal ureteral contractions help propel stones downward 4
Clinical Implications of Stone Movement
The movement of stones from proximal to distal ureter has important treatment implications:
Treatment success rates vary by location - the 2007 AUA guidelines report stone-free rates of:
- 82% for proximal ureteral stones
- 73% for mid-ureteral stones
- 74% for distal ureteral stones 1
Additional procedures needed also vary by location:
- 0.62 procedures per patient for proximal stones
- 0.52 procedures for mid-ureteral stones
- 0.37 procedures for distal ureteral stones 1
Timeframe for Stone Passage
For patients with expectant management:
- Small stones (≤2mm): 95% pass within 31 days
- Medium stones (2-4mm): 95% pass within 40 days
- Larger stones (4-6mm): 95% pass within 39 days 3
Medical Management Considerations
When managing a patient with a ureteral stone that may be moving:
- Medical expulsive therapy (MET) is considered first-line for uncomplicated distal ureteral stones ≤10mm 5
- Alpha-blockers (like tamsulosin) can facilitate stone passage by relaxing ureteral smooth muscle 6
- Pain management with NSAIDs is recommended as first-line therapy 6
- Monitoring stone position with periodic imaging (ultrasound or KUB radiography) is important 6
When Intervention May Be Needed
Intervention may be required if the stone fails to progress:
- For stones ≤2mm: only 4.8% require intervention
- For stones 2-4mm: approximately 17% require intervention
- For stones ≥4mm: up to 50% may require intervention 3
In summary, kidney stones naturally travel from the proximal to distal ureter as part of their passage through the urinary tract, though they may become lodged at anatomical narrowings along the way. The movement pattern and timeframe are influenced by stone size, location, and other factors, with important implications for clinical management decisions.