Overview of traumatic and iatrogenic ureteral injury

INTRODUCTION — Ureteral injury is rare. Compared with injury to other genitourinary (GU) organs, ureteral injury tends to be more often iatrogenic, occurring during pelvic surgery (gynecologic, urologic, or colorectal surgery). When traumatic ureteral injury occurs, most are due to a penetrating mechanism, predominantly in young males. Traumatic injuries are frequently associated with other severe injuries.

Ureteral injuries may only be recognized early if they are specifically evaluated for based on clinical suspicion. Treatment may include placement of a ureteral stent or surgical repair, depending on the severity and location of injury.

The clinical features, diagnosis, and treatment of ureteral injuries are reviewed. The diagnosis and management of upper GU tract injury, lower GU tract injury, and injury to other GU organs are discussed separately. (See "Overview of traumatic upper genitourinary tract injuries in adults" and "Overview of traumatic lower genitourinary tract injury" and "Management of blunt and penetrating renal trauma" and "Traumatic and iatrogenic bladder injury" and "Posterior urethral injuries and management" and "Traumatic injury to the male anterior urethra, scrotum, and penis".)

ANATOMY — The ureters are tubular structures that convey urine from the renal pelvis to enter the bladder posteriorly and inferiorly at the trigone (figure 1). (See "Placement and management of indwelling ureteral stents", section on 'Ureteral anatomy'.)

The ureters are well protected within the retroperitoneum by visceral organs, the psoas muscles, vertebrae, and the pelvic bones. The right ureter is surrounded by the duodenum (anterior), inferior vena cava (medial), ascending colon (anterolateral), and pelvic bones (distal). The left ureter is surrounded by the descending colon (anterior), tail of the pancreas (upper/medial), and pelvic bones (distal).

MECHANISM OF INJURY

Traumatic injury — Ureteral trauma is very rare and is thought to comprise <1 percent of blunt and penetrating genitourinary (GU) trauma [1]. Similar to most trauma demographics, younger males predominate. Penetrating trauma is most common (60 to 77 percent), with gunshot wounds accounting for most injuries [2,3]. The proximal ureter is most involved [4].

Blunt injury can also occur and has a high incidence of associated injuries. Deceleration can result in avulsion of the ureter at the ureteropelvic junction (UPJ) or distally along the ureter [5]. Bilateral UPJ disruption has been reported [6].

Associated injuries — As a result of close associations with surrounding structures, traumatic ureteral injury is highly associated with concomitant injuries to surrounding structures. In one of the largest literature reviews of ureteral trauma, associated injuries were present in 91 percent of patients [7]. The median injury severity score (ISS) was higher for blunt injury (21.5 versus 16) in a review of 582 ureteral injuries [2]. Bowel and vascular injuries were commonly associated with penetrating injury, whereas bony pelvic fracture was associated with blunt ureteral injury. These studies highlight the need to consider possible ureteral injury following significant multiple trauma.

Iatrogenic injury — Iatrogenic ureteral injuries can occur during various abdominopelvic and retroperitoneal surgical procedures [8-10], as well as during endoscopic manipulation, or dissolution of ureteral calculi [11]. Recognition and treatment of ureteral injuries at the time of injury is associated with the least morbidity. (See "Urinary tract injury in gynecologic surgery: Identification and management" and "Management of intra-abdominal, pelvic, and genitourinary complications of colorectal surgery".)

A retrospective review identified 55 patients (11 male and 44 female; mean age 54.5 years) with verified iatrogenic ureteral injury over a 16 year period [9]. Most of the ureteral injuries occurred during gynecologic procedures (55 percent). The remainder of procedures were urologic (25 percent), colorectal (15 percent), and vascular (5 percent). Most iatrogenic injuries were incomplete transection, but perforation (partial or complete), ligation, or complete transection also occurred.

The incidence of injury to the ureters may be lower for a laparoscopic compared with an open surgical approach [12-14]. In a review of over 90,000 colectomies, the incidence of iatrogenic injury for laparoscopic colectomy was 0.53 percent compared with 0.66 percent for open surgery [14]. However, when ureteral injury does occur during laparoscopic surgery, it may be more difficult to identify intraoperatively. The risk for complications related to laparoscopic surgery may be related to the experience of the surgeon but also depends on the type of procedure. (See "Complications of laparoscopic surgery", section on 'Epidemiology and risk factors'.)

Prevention — It is incumbent for the surgeon to demonstrate that due diligence occurred during surgery or another procedure [15]. At a minimum, when the procedure is anticipated to occur in the vicinity of the ureters, the surgeon should document that the ureters were identified and protected or, if this is not possible (eg, adhesions, distorted anatomy), the surgeon should provide the reason. (See "Malpractice risk associated with surgical procedures" and "Urinary tract injury in gynecologic surgery: Epidemiology and prevention".)

In an effort to prevent injury during surgery, prophylactic ureteral stents may be placed prior to surgery to assist with intraoperative identification of the ureter (eg, gynecologic surgery, rectosigmoid surgery, aortoiliac surgery), which is particularly important if the operative field is scarred from previous dissection. Whether stents actually prevent ureteral injury remains debated [16]. In one review of 5729 colectomies, no difference was seen for those who did versus did not undergo preoperative ureteral stent placement [12]. (See "Placement and management of indwelling ureteral stents", section on 'Prophylactic'.)

CLINICAL PRESENTATIONS — There are no clinical signs that are pathognomonic for ureteral injury, once it has occurred.

Clinical suspicion — For patients with blunt or penetrating trauma, the mechanism of injury should guide the level of suspicion for ureteral injury. A history of rapid deceleration, multisystem abdominal trauma (eg, bowel, bladder, pelvic fracture), or penetrating trauma, and clinical features such as flank pain, flank ecchymosis, posterior rib fracture, or spine fractures, should increase suspicion [2,4,17].

Some patients will not have any symptoms or external signs to suggest a ureteral injury. As such, a high index of suspicion is necessary to identify the presence of ureteral injuries. It is important to note that the absence of hematuria cannot be relied upon to exclude ureteral injury [18]. Unlike renal injury, hematuria is an unreliable finding following ureteral trauma as it is present in less than one half of patients with a ureteric injury.

Missed injury/delayed presentation — Ureteral injuries (traumatic, iatrogenic) that are initially missed may become suspected based on symptoms/signs of a urine leak causing urinary ascites, urinoma, ileus, periureteral abscess, sepsis, ureteral fistula, or ureteral stricture. Symptoms may include vague malaise and abdominal/flank pain, nausea/vomiting, fever, and delayed passage of stool/flatus. Examination of the urine may reveal hematuria or pyuria.

One review noted that 38 percent of ureteral injuries were initially missed [4]. In a separate review, among patients who underwent trauma laparotomy, 48 of 429 ureteral injuries were missed [19]. The majority of missed injuries were located in the proximal ureters, a region with less accessibility, particularly in the setting of retroperitoneal hematoma, and therefore with less likelihood of being explored.

DIAGNOSIS — The diagnosis of ureteral injury is typically made using contrast-enhanced computed tomography (CT) scan of the abdomen/pelvis with delayed ureter imaging. If there is a suspicion for a ureteral injury that is not definitively proven by CT scan (initial or repeat), then cystoscopy with retrograde pyelography can aid the evaluation.

For trauma patients with indications for immediate laparotomy, the diagnosis will necessarily be made during exploration of the ureters when injury is suspected. Direct inspection of the ureters is the most sensitive method to assess for ureteral injury. Intravenous dyes (eg, methylene blue, indigo carmine) can be used to assess for dye leakage along the course of the ureter. The intraoperative approach for identification of suspected iatrogenic ureteral injury is similar. (See "Urinary tract injury in gynecologic surgery: Identification and management".)

CT urography — For hemodynamically stable patients with suspected ureteral injuries, we suggest using contrast-enhanced abdominal/pelvic CT with delayed imaging (CT urography). For penetrating trauma, a trajectory in proximity of the ureters may signal the need for evaluation of the ureters even in the absence of other signs. The advantages of CT outweigh the risks, which include contrast-related complications, radiation exposure, and the dangers of transporting a trauma patient away from the resuscitation environment into the CT scanner [20].

For patients taken to the operating room emergently without imaging studies, some experts have suggested that postoperative CT scan may reduce the incidence of missed injuries [21,22]. (See "Overview of inpatient management of the adult trauma patient", section on 'Consider other potential injuries'.)

Identification of ureteral injuries requires a delay of 10 minutes after the administration of intravenous (IV) contrast to allow contrast to reach the ureters [23]. When the situation allows, 10 minute delayed imaging is preferred for a more complete evaluation of the upper urinary tract. To reduce radiation exposure, delayed phase imaging can be performed with a low-dose protocol and increased axial image slice thickness (5 mm). Repeated scans at a later interval may be necessary if there is poor renal excretion of IV contrast at 10 minutes.

Findings that suggest ureteral injury include nonvisualization of the ureter, contrast extravasation from the ureter, ipsilateral hydronephrosis, and poor renal excretion localized to one side [5,24-28]. If the initial delayed images do not adequately opacify the ureters, further delayed imaging may be necessary if ureteral injury is still suspected.

To reduce radiation exposure during repeat CT imaging, we perform a low-dose "CT urinoma" study, which omits the parenchymal phase. This study involves a low-dose noncontrast phase followed by a delayed image phase 10 minutes after intravenous contrast administration.

Ureter injury grading — The American Association for the Surgery of Trauma (AAST) grading system for ureteral injury (table 1) is rarely reported in the medical literature. The grading system relies on visual inspection of the injury to make a diagnosis since injury grades are difficult to assess using imaging alone. Rather than stratifying ureteral injuries by grade, most surgeons distinguish them based upon location of ureteral injury (upper, mid, lower), mechanism of injury (blunt versus penetrating), and severity of injury (complete versus partial transection) as these categories guide the type of surgical management necessary for repair. (See "Overview of traumatic upper genitourinary tract injuries in adults", section on 'Injury grading'.)

TREATMENT — Ureteral injuries generally will require some form of treatment, either using minimally invasive or open reconstructive techniques. Data to guide conservative management of ureteral injuries are limited; minimally invasive techniques are often necessary when this treatment strategy is pursued. Patients who are being followed conservatively and demonstrate worsened urinary extravasation on repeat imaging should be treated with placement of a ureteral stent and urethral catheter (if not already in place) to reduce pressure and promote healing [29]. (See 'Stenting traumatic injury' below and "Placement and management of indwelling ureteral stents".)

General principles — Most traumatic ureteral injuries occur in the setting of concomitant injuries that often require exploratory laparotomy. Ureteral injuries identified intraoperatively should generally be repaired surgically, unless there is complex injury, or other severe concomitant injuries limiting allowable time [30-35]. If reconstruction cannot be undertaken, temporary urinary drainage is used to control urine until definitive repair/reconstruction can be undertaken [36-45].

As examples:

●For uncomplicated incomplete ureteral injury, retrograde ureteral stenting can be attempted.

●For complete ureteral transections, a perinephric tube can be placed and formal repair performed within the first seven days after injury, if possible, or delayed three months later depending on the patient's clinical status.

When ureteral injury is not recognized and presents in a delayed fashion (>7 days), retrograde imaging with ureteral stent placement should be attempted initially [37-43]. When the injury is located near a suture line (eg, bowel, vagina), or if the patient requires surgery for another reason, immediate repair can be considered. If stent placement is unsuccessful or not possible, percutaneous nephrostomy should be performed. Aspiration and/or drainage of an associated abscess may be necessary if ureteral stenting or a nephrostomy tube does not successfully contain the ureteral injury. For complicated injuries with abscess or urinoma formation, initial percutaneous nephrostomy with periureteral drainage is preferred with plans for delayed ureteral reconstruction at a later date.

In general, iatrogenic urinary tract injury recognized during surgery should also be repaired intraoperatively when identified rather than delaying for a subsequent surgery, if possible. (See "Surgical repair of an iatrogenic ureteral injury".)

Iatrogenic injuries that occur during endoscopic procedures can initially be managed with a ureteral stent. If placement of a ureteral stent is not possible or if stent placement fails to adequately divert the urine, then a percutaneous nephrostomy tube should be placed. If there is a large urinoma, a periureteral drain can be placed subsequently. Delayed ureteral reconstruction is often necessary [37,38,41,44,46-48].

Stenting traumatic injury — Ureteral stent placement is an option for limited blunt ureteral contusion (eg, periureteral contusion from gunshot blast) and some penetrating ureteral injuries (partial injury) depending on the degree of surrounding tissue damage. However, when tissue viability is questionable, excision and ureteral reconstruction are strongly preferred.

Following stent placement, subsequent imaging using a contrast-enhanced CT scan with delayed images or a retrograde pyelogram can be performed to assess appropriate ureteral healing before or after ureteral stent removal to ensure a ureteral stricture has not developed.

Ureteral repair/reconstruction — Ureteral injury is highly associated with the need for repair (97 percent of cases in one study) [3]. Ureteral repair should be performed at the time of initial laparotomy, when possible. Surgical options to repair a ureteral injury include primary reapproximation, spatulated ureteroureterostomy, and ureteral reimplantation with possible adjunctive surgical techniques (ie, psoas hitch and/or Boari bladder flap) [49]. These techniques are similar to those used to repair iatrogenic ureteral injury. (See "Surgical repair of an iatrogenic ureteral injury".)

The blast effect from penetrating gunshot injuries can cause tissue ischemia and lead to delayed necrosis. Thus, adequate debridement and reconstruction is recommended at the time of laparotomy, depending on the extent of ureteral tissue involvement.

The ureter should be debrided and repaired using a spatulated tension-free primary repair over a ureteral stent, when possible.

●Proximal and midureteral injuries can be treated using primary closure or spatulated ureteroureterostomy (figure 2). If the anastomosis cannot be performed without tension, the ureter can be mobilized, which should be done in a manner that preserves maximal blood supply.

●For distal ureteral injuries (ie, distal to iliac vessels), ureteral reimplantation of the proximal injured ureter to the bladder is recommended. The psoas hitch (figure 3) and Boari flap (figure 4) are used when additional mobility is needed to increase successful ureteral reimplantation.

If the injury cannot be managed adequately in the acute setting, ureteral ligation with percutaneous nephrostomy tube placement is advised, followed by delayed ureteral reconstruction [2,18,35,50-53]. (See 'Ligation of traumatic injury' below.)

Autotransplant (figure 5) or ileal ureter interposition (figure 6) is reserved for definitive management of complex ureteral injuries and should not be performed in the acute setting. For severe collecting system injuries, ureteral stent and bladder catheter or nephrostomy tube placement is recommended for acute management with delayed ureteral reconstruction three to six months later.

Ligation of traumatic injury — For ureteral injury in patients who are hemodynamically unstable due to severe concomitant injuries, the ureter can be ligated to prevent urine extravasation. Subsequent options for urinary drainage include:

●Placement of a nephrostomy tube.

●Placement of a stent into the ureter with externalization of the stent as a conduit.

●The ureter can be externalized through a separate incision and sutured to the skin, akin to a "stoma."

The author prefers placement of a nephrostomy tube based on experience, as the latter two options can be associated with complications (dislodgment of externalized ureteral stent, stenosis of percutaneous ureterostomy). Ureteral reconstruction can be performed once the patient has stabilized, within a timeframe of five to seven days, but if this is not possible, then delayed reconstruction is recommended.

FOLLOW-UP CARE AND IMAGING — For patients with indwelling ureteral stents, routine care is discussed separately. (See "Placement and management of indwelling ureteral stents", section on 'Routine patient care'.)

Radionuclide scintigraphy (ie, mercaptoacetyltriglycine [MAG3] renogram with furosemide) at 3 and 12 months following ureteral repair is helpful to assess patency of the reconstructed ureter.

Prior to delayed reconstruction (a minimum of three months if the injury progresses to a ureteral stricture), preoperative antegrade nephrostogram with or without combined retrograde pyelogram can aid surgical planning.

COMPLICATIONS — Perinephric urinoma can develop following collecting system or ureteral injury that does not heal. Most patients will present with fever, chills, and/or flank pain 7 to 10 days after acute injury. Contrast-enhanced computed tomography (CT) scan with delayed images provides the diagnosis. Treatment involves placement of a perinephric drain and appropriate antimicrobial therapy (image 1).

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Genitourinary tract trauma in adults".)

SUMMARY AND RECOMMENDATIONS

●Ureteral injury – Ureteral injury is very rare. Compared with other genitourinary (GU) organs, ureteral injury tends to be more often iatrogenic. Most traumatic ureteral injuries are due to penetrating trauma, with younger males predominantly affected. Traumatic ureteral injury is highly associated with concomitant injuries. (See 'Mechanism of injury' above.)

●Clinical presentations – A suspicion for traumatic ureteral injury is based on an appropriate mechanism of injury and clinical findings. Hematuria is present in less than one half of patients with a ureteral injury. Clinicians should be mindful to assess for a potential ureteral injury when new symptoms of fever, flank pain, sepsis, and/or ileus occur following initial trauma stabilization, or following pelvic surgery. (See 'Clinical presentations' above.)

●Diagnosis

•Imaging – In hemodynamically stable patients, the diagnosis of ureteral injury is typically made using contrast-enhanced computed tomography (CT) scan of the abdomen/pelvis. Identification of ureteral injuries requires a delay of 5 to 10 minutes after the administration of intravenous (IV) contrast to allow contrast to reach the ureters. If suspicion remains high in the setting of a negative CT scan, then retrograde pyelogram is recommended. (See 'CT urography' above.)

•Intraoperative – In the operating room (eg, trauma patients requiring laparotomy, suspected intraoperative injury), direct inspection of the ureters is the most sensitive method to assess for ureteral injury. Intravenous dyes (eg, methylene blue, indigo carmine) can be used to aid the assessment looking for dye leakage along the course of the ureter. (See 'Diagnosis' above and "Urinary tract injury in gynecologic surgery: Identification and management".)

●Treatment – Ureteral injuries generally require some form of treatment. Minimal blunt ureteral injuries and partial penetrating injuries may be amenable to ureteral stenting. Ureteral repair should be performed when injury is identified at the time of laparotomy, if possible. For severe injuries, ligation of the ureter with urinary drainage and delayed reconstruction may be necessary. (See 'Treatment' above.)