Ureteroscopy · proximal ureter
The avulsion
Teaching only · not for diagnosis or treatment decisions
Case orientation
The normal sequence
Ureteroscopy for a ureteric stone is a see-as-you-go operation. The semirigid scope handles the distal and mid ureter, the flexible scope reaches the upper ureter and kidney.
Holmium laser is the workhorse: the stone is dusted or fragmented to passable pieces, and only small free fragments are basketed if they are retrieved at all. The whole list is run against the ureter, not against the stone.
Gentle telescoping advance under direct vision, with a wire down to the kidney, is the constant. Nothing is advanced against resistance, and nothing is withdrawn against resistance either.
- Cystoscopy, then a safety guidewire passed up the ureter into the renal pelvis under vision and fluoroscopy.
- Semirigid ureteroscopy alongside the wire, inspecting the ureter up to the stone with gentle irrigation.
- Laser fragmentation, dusting the stone or reducing it to fragments small enough to pass spontaneously.
- For the upper ureter or kidney, a flexible scope over the wire, often through a ureteric access sheath placed under fluoroscopy.
- Basket only small, free fragments under direct vision, never an impacted stone wider than the lumen.
- Final inspection of the whole ureter for mucosal integrity.
- JJ stent placed over the wire, with a check that both ends sit correctly.
where it bites
- Avulsion lurks at the moment a basket engages a stone too large to pass and the operator pulls the scope down rather than disengaging.
01 The model
Where the danger lives
01 The model
schematic / ureteroscope view
Layers
Spatial caption
- The proximal ureter has the thinnest, least supported muscular wall, which is why avulsion almost always happens here rather than in the distal third.
02 The mechanism
How it happens
- The ureter avulses when a basket grips a stone too wide for the lumen and the whole assembly is dragged down.
- The wall fails at its weakest point, the upper ureter.
- Three things stack.
- An impacted proximal stone, often softened or scarred by previous shockwave lithotripsy, sits in a basket closed firmly around it.
- The operator withdraws the engaged basket, or forces a scope or oversized access sheath through a tight upper segment.
- Because the proximal wall is thin and poorly supported, longitudinal traction concentrates there.
- A short pull strips the mucosa inside out.
- Sustained pull degloves a long segment, the scabbard avulsion, or breaks the ureter at two points and delivers a tube of ureter on the scope.
- The give is sudden and unmistakable.
- What comes back is not stone but ureter.
- Impacted stone in the proximal ureter
- Basketing a fragment wider than the lumen
- Previous shockwave lithotripsy or a strictured segment
- Pulling an engaged basket or scope against resistance
- Oversized access sheath forced through a narrow upper ureter
- Incidence. Rare; one large single-centre series reports 3 avulsions in 4,645 procedures, and reviews quote rates from 0.06% to 3.75%. [source traced]
- Alapont JM, Broseta E, Oliver F, Pontones JL, Boronat F, Jimenez-Cruz JF. Ureteral avulsion as a complication of ureteroscopy. Int Braz J Urol. 2003;29(1):18-23. PMID 15745462. Gaizauskas A, Markevicius M, Gaizauskas S, Zelvys A. Possible complications of ureteroscopy in modern endourological era: two-point or scabbard avulsion. Case Reports in Urology. 2014;2014:308093. PMID 25610699.
- [source traced] Gaizauskas A et al. Possible complications of ureteroscopy in modern endourological era: two-point or scabbard avulsion. Case Reports in Urology. 2014;2014:308093.
03 The save
The first moves
- Stop pulling. Do not yank the basket or the scope. Resistance on withdrawal is a warning, not something to power through.
- If a stone is basketed and stuck, disengage it: open the basket, laser the stone through the basket to release it, or cut the basket wire at the handle and leave it to retrieve later. Never force a stuck basket.
- Inspect the ureter along its length under vision. Look for inverted mucosa, a circumferential defect, or a free tube of ureter on the instrument.
- If avulsion is confirmed, treat it as a major ureteric injury: keep a wire to the kidney if one is still in place, stop, and call the senior on-call urologist. This is the conversion and escalation trigger. escalation trigger
- Preserve the kidney and control urine drainage. A nephrostomy with a damage-control approach is reasonable when immediate reconstruction is not feasible.
- Plan definitive repair by level and length: ureteroneocystostomy or Boari flap for distal loss, ileal ureter or autotransplantation for long proximal loss, usually open or staged.
- Document fully: stone position, instrument and basket used, the moment and nature of the give, the segment lost, wire and drainage status, the senior informed, and the consent and counselling for reconstruction.
04 The viva answer
The viva answer
- Ureteric avulsion is the most feared mechanical complication of ureteroscopy.
- It is rare, and most series report well under one percent, but it is a major injury that usually ends in formal reconstruction, so the examiner is testing prevention and recognition as much as repair.
- It happens almost always in the proximal ureter, where the muscular wall is thinnest and least supported.
- The classic mechanism is withdrawal of a stone basket engaged on a fragment too wide to pass through the lumen, dragging the ureter down with it.
- Previous shockwave lithotripsy, an impacted stone and an oversized access sheath all add risk.
- My priority is prevention.
- I would never basket a stone wider than the ureteric lumen, and I would laser to dust or to passable fragments first.
- No instrument is advanced or withdrawn against resistance.
- If a basket became stuck, I would not pull.
- I would disengage it by opening it, lasering the stone through it, or cutting the basket wire and retrieving it later.
- If avulsion occurred, the give is sudden, and ureter rather than stone returns on the scope.
- I would stop, keep a wire to the kidney if possible, and call my senior immediately.
- The kidney is preserved with a nephrostomy and damage control if needed.
- Definitive repair depends on level and length: ureteroneocystostomy or Boari flap distally, ileal ureter or autotransplantation for long proximal loss.
- I would document the event in full and counsel the patient honestly.
- Why is the proximal ureter the segment that avulses?
- Its muscular wall is thinner and it is the least supported part of the ureter, so longitudinal traction concentrates there and the wall fails at that point rather than distally.
- A basket is stuck on a stone in the upper ureter. What are your options?
- Do not pull.
- Open the basket to release the stone, laser the stone through the basket to free it, or cut the basket wire and leave the fragment and basket to be retrieved at a later sitting.
- Force is never an option.
- You have a long proximal avulsion. How is it definitively managed?
- Long proximal loss usually cannot be bridged by simple reimplantation.
- Options are ileal ureter interposition or renal autotransplantation, depending on the length lost and the patient.
- A nephrostomy preserves the kidney while reconstruction is planned.
Strong pass
Anyone can say repair the ureter.
Examiner note
The strong answer leads with prevention, never basketing a stone wider than the lumen and lasering first, names disengaging a stuck basket by lasing through it or cutting the wire rather than pulling, and matches the reconstruction to the level and length of loss rather than offering one generic operation.
Now close the card
Can you give it back without looking?
Allow about four minutes to order the save, answer the follow-ups and compare your viva response with the card. Your scores guide a suggested revision schedule in this browser.