Introduction

The avulsed ureter is a severe urological injury often associated with iatrogenic trauma. While relatively rare, the consequences of ureteral avulsion are significant, leading to potential loss of the renal unit and requiring complex surgical interventions. It represents a nightmare scenario for urologists and patients alike. This article delves into the pathophysiology of ureteral avulsion, ways to prevent the injury, how to stage the trauma, and treatment options.

Epidemiology

Ureteral avulsion is uncommon, with most cases occurring due to iatrogenic causes, such as ureteroscopy or abdominal surgeries. The incidence of ureteral injuries in general ranges from 0.3% to 1.5% in major gynecological surgeries, with a smaller subset being avulsions. Trauma, although a less frequent cause, can result in ureteral avulsion, particularly in high-impact situations such as high-speed motor vehicle accidents or severe falls from height. Ureteral injuries are more prevalent in males, likely due to a higher incidence of trauma-related causes.

Pathophysiology

Ureteral avulsion involves the tearing away of the ureter from its attachments, which can occur at various points along its length. The ureter is vulnerable to injury due to its relatively fixed points at the renal pelvis and the bladder. The proximal ureter near the ureteropelvic junction has a thinner muscular wall. During ureteroscopy, the scope can get stuck in the ureter, and if force is applied, the ureter can be severed (Figures 1 and 2 ). Flexible scopes and baskets can get lodged in the ureter if the stone is still too large to pass. The proximal portion of the semi-rigid ureteroscopes can get stuck in the intravesical ureter. This can lead to the scabbard avulsion, where the ureter appears as a ureteroscope sheath upon exiting the body.¹

The avulsion can lead to urine leakage into the surrounding tissues, causing urinoma, abscess formation, and peritonitis. Additionally, the injury disrupts the blood supply to the ureter, potentially resulting in ischemia and necrosis of the affected segment. If not promptly managed, ureteral avulsion can lead to severe complications, including irreversible renal function loss and urosepsis.

How to Avoid

During pelvic and abdominal surgeries, awareness and proactive ureteral identification are key to avoiding iatrogenic avulsion. In patients scheduled for ureteroscopy, they should be counseled preoperatively that their surgery may be staged. In some scenarios, based on surgeon judgment, placing a stent first for passive dilation and coming back later to treat the stone can be preferred. During ureteroscopy, urologists should avoid using excessive force or yanking the scope if stuck. A basketed stone should be a short distance from the scope and visible as one withdraws the scope to give the surgeon perspective on whether the proximal tissue is being intussepted.

If the scope does get stuck, several tricks can be employed for removal. If the scope is stuck from your basket being lodged, try passing a small laser fiber in the working channel to further fragment a stone. Alternatively, cut the basket outside the ureteroscope and reinsert the scope along the basket to fragment. If the rigid scope is stuck from advancing too far, use a small endoscope to incise the ureteral orifice medially to release the scope. If the scope is stuck in the deflected position, straighten manually with a coaxial dilator alongside the scope or cut the handle of the URS and cut distal end with percutaneous access.

Assessment and Staging

After the injury occurs, careful assessment of the length, location, and degree of injury is needed. In the acute setting, definitive reconstruction is possible after consulting with the patient and their family; however, working to drain the injured renal unit is the main priority. In most cases, delaying repair is best so that a surgeon with experience in ureteral reconstruction can help. Staging with antegrade and retrograde fluoroscopy is required. Beyond staging the ureter, assessing bladder capacity is critical for mid and distal injuries where a direct connection to the bladder plays a bigger role.

Treatment Based on Location

The treatment of an avulsed ureter varies depending on the location of the injury along the ureter: proximal, mid, or distal. Whether someone uses open or robotic techniques depends on surgeon skill set and preference. The rise of robotic surgery has led to replication of open techniques in a minimally invasive fashion, reducing blood loss and patient convalescence. As a reconstructive principle, employing the most straightforward or simple solution is often the best. Determining patient risks for future renal disease will contribute to how far one should go to preserve a renal unit.

Distal injuries are the easiest to treat. Depending on the location, a direct reimplant, a psoas hitch, or Boari flap can be employed. Midureteral injuries are more nuanced. When a direct anastomosis is not possible, adjuncts, such as the use of buccal grafts (Figure 3) or interposing appendix or bowl, may be needed. Total or subtotal proximal injuries are the most devastating types of ureteral avulsions. Options include lifelong nephrostomy tube, nephrectomy, ileal ureter (Figure 4), and autotransplant. Every approach and its relative risks and benefits should be carefully considered with the patient and their family.

Conclusion

Ureteral avulsion is a devastating complication. Awareness of the potential for this injury is critical. Basic principles of ureteroscopy and what to do in special situations when the scope becomes stuck are mandatory knowledge for all urologists. The choice of surgical intervention depends on the location of the injury and the extent of damage, with various reconstructive techniques, robotic or open, available to ensure the best possible outcomes.