Upper Urinary Tract Trauma

Includes 2020 AUA Guideline Notes on Urotrauma

See Original 2020 AUA Guidelines on Urotrauma

See Lower Urinary Tract Trauma Chapter Notes

Trauma background

• Leading cause of death in US population aged 1-44
• Injuries are frequently classified as blunt vs. penetrating due to differences in management and outcomes
  • Blast injuries may be associated with both penetrating and blunt trauma, and are most common in the setts of violent conflict
• Urologic organs are involved in ≈10% of abdominal traumas

Renal Trauma

Epidemiology

• Most commonly injured GU organ in trauma

Pathogenesis

• Kidneys are particularly prone to deceleration injuries (e.g. falls, motor vehicle collisions) because they are fixed in space only by the renal pelvis and the vascular pedicle
• The pediatric kidney is believed to be more susceptible to trauma
  • Mechanisms owing to a decrease in the physical renal protective mechanisms found in children (4):
    1. Immature, more pliable thoracic cage
    2. Weaker abdominal musculature
    3. Less perirenal fat
    4. Sits in a lower abdominal position

Diagnosis and evaluation

History and physical exam

History

• Most important information in blunt renal injury is the extent of deceleration involved in high-velocity impact trauma
• Trauma to the anterior axillary line is more likely to damage important renal structures such as the renal hilum and pedicle compared to the posterior axially line, which more commonly results in parenchymal injury

Physical exam

• Findings indicating possible renal injury (5):

1. Flank hematoma
2. Abdominal or flank tenderness
3. Rib fractures
   • Ipsilateral rib fracture can increase the incidence of significant renal trauma by 3x
4. Penetrating injuries to the low thorax or flank
5. Hematuria
   • The degree of hematuria and the severity of the renal injury do not consistently correlate; presence or absence of hematuria should not be the sole determinant in the assessment of a patient with suspected renal trauma

Imaging

• Indications
  • AUA: indications for imaging (contrast enhanced CT with immediate and delayed films) in stable trauma patients (5):
    1. Gross hematuria
    2. Microscopic hematuria and systolic blood pressure < 90mmHG
    3. Mechanism concerning for renal injury (e.g., rapid deceleration, significant blow to flank)
    4. Physical exam findings concerning for renal injury (e.g. rib fracture, significant flank ecchymosis)
    5. Penetrating injury of abdomen, flank, or lower chest
    • Generally, children can be imaged using the same criteria as adults. Children, however, often do not exhibit hypotension as adults do.
  • Campbell’s indications for imaging (similar to AUA indications but worded differently)
    1. All blunt trauma with gross hematuria
    2. All blunt trauma with microhematuria and hypotension (defined as a SBP <90 mm Hg at any time during evaluation and resuscitation)
    3. All blunt trauma with significant acceleration/deceleration mechanism of injury, specifically rapid deceleration as would occur in a high-speed motor vehicle accident or a fall from heights
    4. All penetrating trauma with a likelihood of renal injury (abdomen, flank, or low chest entry/exit wound) who are hemodynamically stable enough to have a CT (instead of going right to the operating room or angiography suite)
    5. All pediatric patients with greater than 5 RBCs/HPF

• Modality
  • CT abdomen/pelvis with IV contrast (with immediate and delayed images) should be performed when there is suspicion of renal injury (AUA)
    • In children, ultrasound may be used, although CT is preferred
    • An intraoperative one-shot IVP (2 mL/kg IV bolus of contrast with a single image obtained 10-15 minutes later) may be used to confirm that a contralateral functioning kidney is present in rare cases where the patient is taken to the operating room without preliminary CT scan if surgeons are considering renal exploration or nephrectomy
    • Major limitation of CT scan in renal trauma: inability to adequately define a renal venous injury adequately.
      • A medial hematoma strongly suggests a venous injury, however, there is no imaging modality which can accurately diagnose a venous injury

• CT findings suspicious for significant renal injury include (6):
  1. Medial laceration
  2. Medial hematoma (vascular pedicle injury)
  3. Medial urinary extravasation (renal pelvis or ureteropelvic junction injury)
  4. Hematoma > 3.5cm
  5. Lack of contrast enhancement of the parenchyma (main renal arterial injury)
  6. Active intravascular contrast extravasation (arterial injury with brisk bleeding)

CT scan showing left renal artery injury (source: Wikipedia)

• Differential diagnosis of fluid collections seen on serial imaging for renal trauma (3):

1. Hematomas - density is almost always > 30 HU
2. Urinomas - density ranges from 0-20 Hounsfield units (HU)
3. Abscesses -associated with rim enhancement; perinephric abscess rarely occurs after renal injury

AAST Grading

(Table to be created)

*Advance one grade for bilateral injury up to grade III

What Grade of injury is this based on the AAST classification?

Source: Wikipedia

Management

• Management of traumatic renal injuries has shifted from operative exploration to non-operative management in the vast majority of cases.
  • Non-operative management of the vast majority of blunt renal injuries is firmly established; non-operative management of penetrating and high-grade renal injuries remains debatable
• Indications for intervention
  • AUA: based on hemodynamic stability
    • If hemodynamically stable: non-invasive management
      • Non-invasive management includes close hemodynamic monitoring, bed rest, ICU admission, and blood transfusion (when indicated)
      • Patients initially managed noninvasively may still require surgical, endoscopic, or angiographic treatments at a later time, especially those with higher grade injuries.
      • Factors associated with increased risk of bleeding and need for intervention in grade 3 and 4 injuries:
        1. Medial hematoma
        2. Hematoma > 3.5-4 cm in thickness
        3. Presence of a contrast extravasation from vessels on imaging
      • Although devitalized parenchyma has been suggested as a risk factor for development of septic complications, evidence supporting intervention for this radiographic finding is inconclusive
      • All patients with high-grade injuries selected for nonoperative management should be closely observed with serial hematocrit readings and vital signs (Campbell’s)
        • Some empirically prescribe bed rest until gross hematuria resolves, though insufficient evidence to support its efficacy
    • If hemodynamically unstable: immediate intervention (surgery or selective angioembolization)
      • For hemodynamically unstable patients with radiographic findings of large perirenal hematoma (> 4 cm) and/or vascular contrast extravasation in the setting of deep or complex renal laceration (AAST Grade 3-5), surgeons should perform immediate intervention
        • Perinephric hematoma size provides a rough radiographic estimate of the magnitude of renal bleeding, and increasing hematoma size has been incrementally associated with higher intervention rates.
      • Selected patients with bleeding from segmental renal vessels may benefit from angioembolization as an effective yet minimally invasive treatment to control bleeding
        • Selective embolization provides an effective and minimally invasive means to stop active bleeding from parenchymal lacerations and segmental arterial injury
        • Increasingly used in renal trauma
      • Patients who are hemodynamically unstable despite active resuscitation should be taken to the operating room rather than angiography
  • Campbell’s 11th edition
    • Indications for operative management
      • Absolute (4) 5PUPS:
        1. Suspected grade 5 injury (renal vascular pedicle avulsion)
        2. Expanding/Pulsatile renal hematoma (usually indicating renal artery laceration)
           • Some blunt and penetrating abdominal trauma may require laparotomy because of associated non-urologic injury, but even in these cases it is not necessary to explore the kidney additionally. However, exploration is needed in the case of a pulsatile and expanding retroperitoneal hematoma that suggests renal artery laceration
        3. UreteroPelvic junction disruption
        4. Hemodynamic instability with Shock
      • Relative indications (3):
        • Renal injury together with colon/pancreatic injury
        • Urinary extravasation with significant renal parenchymal devascularization
        • Delayed diagnosis of arterial injury
      • Surgical management
        • Nephrectomy is a frequent result when hemodynamically unstable patients undergo surgical exploration
        • Approach: transabdominal
          • Allows complete inspection of intra-abdominal organs and bowel.
        • Principles of renal reconstruction after trauma include (8):
          1. Complete renal exposure
          2. Measures for temporary vascular control
          • • Isolate the renal vessels before exploration to provide the immediate capability to occlude them if massive bleeding should ensue when the Gerota fascia is opened
          1. Limited debridement of nonviable tissue
          2. Hemostasis by individual suture ligation of bleeding vessels
          3. Watertight closure of the collecting system if necessary/possible
          4. Reapproximation of the parenchymal defect
          5. Coverage with nearby fascioadipose flaps (Gerota fascia or omentum) if feasible*******##The open parenchyma should be covered when possible by a pedicle flap of omentum. The rich vascular and lymphatic supply of the omentum promotes wound healing and decreases the risk for delayed bleeding and urinary extravasation.
          6. Liberal use of drains
        • For major renovascular injuries in patients with 2 kidneys, speedy nephrectomy is advocated
          • In rare instances in which vascular repair is technically feasible, renal salvage rates are disappointingly low
        • In damage control surgery, the area around the injured kidney is packed with laparotomy pads to control bleeding, with a planned return in approximately 24 hours to explore and evaluate the extent of injury.
          • This allows the cold, acidotic, and coagulopathic patient to be stabilized in the ICU before any attempt at potentially lengthy renal reconstruction is attempted.
        • In an unstable patient, if damage control is not an option, total nephrectomy would be indicated immediately when the patient’s life would be threatened by attempted renal repair.
        • Delayed renal bleeding can occur up to several weeks after injury but usually occurs within 21 days.
      • Renal injury with urinary extravasation

Ureteral Trauma

Epidemiology

Rare, accounting for 1% of urologic injuries.

Pathogenesis Acute ureteral injury results from (3): Iatrogenic injury (open surgery, laparoscopy, and endoscopic procedures)

External violence from high-speed blunt mechanisms

The presence of massive force injuries in the patient with blunt trauma should always increase the level of suspicion for ureteral injury

Penetrating stab and gunshot wounds

Iatrogenic injury Procedures most commonly associated with iatrogenic ureteral injuries: Hysterectomy (54%)

Colorectal surgery (14%)

Ovarian tumor removal (8%)

Transabdominal urethropexy (8%)

Abdominal vascular surgery

Compared to open surgery, ureteral injuries during laparoscopic surgery are less likely to be recognized immediately. During laparoscopy/robotic surgery, a high index of suspicion for ureteral injury is required.

In open surgery, 1/3 of ureteral injuries are recognized immediately.

Intraoperative assessment of ureters Some have advocated maneuvers to check the patency of the ureter after all surgeries in which ureteric injury is commonly reported (e.g., hysterectomy).

Options (3): Direct inspection

Purposefully opening the retroperitoneum before or after hysterectomy has been advocated to avoid ureteral injury or at least allow intraoperative detection.

Injection of 5-10 mL of IV methylene blue or indigo carmine dye followed by cystoscopy Poor predictor of injury

Goal of cystoscopy is to document the absence of hematuria and the presence of bilateral ureteral jets

IV methylene blue and indigo carmine are generally considered to be benign drugs, but their use has resulted in patient deaths and fetal deaths when used in pregnant women. Contraindications for IV methylene blue (3):

Pregnancy

Use of selective (e.g., paroxetine, sertraline, fluoxetine, fluvoxamine, citalopram) or nonselective (e.g., imipramine) serotonin reuptake inhibitors

Methylene blue is a potent monoamine oxidase inhibitor and has caused deaths from serotonin toxicity in patients taking medications that increase serotonin levels

Glucose-6-phosphate dehydrogenase deficiency Causes methemoglobinemia and hemolysis

Contraindications for IV indigo carmine: Pregnancy

IV indigo carmine has been implicated in rare but serious cases of bronchospasm, bradycardia, hypertension, hypotension (most common), and anaphylactoid reactions.

Retrograde pyelography

Not effective Intraooperative single-shot IVP

Intraoperative hydration or diuretic administration Has been suggested to enhance ureteral visualization and potentially decrease the risk for injury

No data to support this method

Digital palpation of the ureter Appears to be ineffective

Grasping the ureter with forceps to evoke ureteral peristalsis Highly ineffective; should never be relied upon.

Preoperative ureteral stenting May increase intraoperative recognition of ureteral injury

A randomized trial demonstrated that prophylactic stenting does not reduce the risk of ureteral injury in women undergoing gynecologic surgery§

Ureteral stents are not without complications

Endoscopic injury Ureteroscopy should be performed alongside or over a wire placed up into the renal pelvis

Factors associated with higher complication rates during ureteroscopy (4): Longer surgery times

Treatment of renal calculi

Surgeon inexperience

Previous irradiation

Persistence of stone basket attempts after recognition of a ureteral tear is a cause of ureteral injury during ureteroscopy. When ureteral perforation is identified, stop the procedure and place a ureteral stent

Intraoperative ureteral manipulation Common after aortoiliac and aortofemoral bypass surgery (12-20%) and may result in hydronephrosis Management: course is benign in most; if symptomatic, can be treated with steroids

Ureteral contusion Can occur in the context of a gunshot wound with blast injury

Complications may include delayed ureteral stricture and/or overt ureteral necrosis with urinary extravasation

Diagnosis and evaluation History and physical exam Hematuria is a non-specific indicator of urologic injury

Significant ureteral injury can occur in the absence of hematuria

Post-operative signs and symptoms of missed ureteral injury (6): Flank pain

Fever

Leukocytosis

Ileus

Abdominal distention

Urinary fistula

Imaging Indications (contrast enhanced CT with 10 minute delayed films) for imaging (1) (AUA) Stable trauma patients with suspected ureteral injuries and not proceeding directly to laparotomy

If the initial delayed images do not adequately opacify the ureters, further delayed imaging may be necessary if ureteral injury is still suspected.

Findings suggestive of ureteral injury (4): Contrast extravasation

Lack of contrast in the ureter distal to the suspected injury

Ipsilateral delayed pyelogram

Ipsilateral hydronephrosis

Other Direct inspection during laparotomy in trauma patients with suspected ureteral injury who have not had preoperative imaging

AAST Grading Grade I: contusion or hematoma without devascularization

Grade II: laceration with < 50% transection

Grade III: laceration with ≥ 50% transection

Grade IV: laceration with complete transection and < 2cm devascularization

Grade V: laceration with avulsion and > 2cm of devascularization

Management Based on hemodynamic stability If hemodynamically stable: Traumatic ureteral lacerations should be repaired immediately A longitudinal laceration is converted into a transverse one so as not to narrow the ureteral lumen (Heineke-Mikulicz procedure)

If hemodynamically unstable: temporary urinary drainage followed by delayed definitive repair Options for temporary urinary drainage (4): Ureteral stent (internalized double J or exteriorized single J) only

Short period of observation with a plan for reoperation when the patient is more stable, usually within 24 hours

Exteriorize the ureter

Tie off the ureter (with long silk sutures for easy identification at time of delayed repair) and plan percutaneous nephrostomy

Definitive repair of the injury should be performed when patient has improved/stabilized

Special scenarios Ureteral contusion Options, depending on ureteral viability and clinical scenario (2): Ureteral stenting

Resection with primary repair

Indications for resection with primary repair (2): Severe or large areas of contusion

Gun-shot related ureteric contusions

With a gun-shot related injury, excise devitalized tissue and an adjacent segment of normal-appearing ureter to eliminate late ischemia and stricture formation from the blast effect. Once both ends of the ureter have been adequately trimmed to healthy areas, mobilized, and correctly oriented, they are spatulated for ≈5-6 mm. Spatulation is performed for both ureteral segments at 180° apart

In ureteral contusions that do not appear to require excision/anastomosis, a ureteral stent should be placed; only truly minor injuries can go untreated, but the patients should be watched for signs of delayed urine leak.

Delayed diagnosis: ureteral stent If ureteral stent placement unsuccesful or not possible (proximal ureter is completelely transected or patient instability preculdes attempts at retrograde placement), perform percutaneous nephrostomy with delayed repair If nephrostomy alone does not adequately control the urine leak, options then include placement of a periureteral drain or immediate open ureteral repair

Indications for immediate repair for delayed diagnosis (within 1 week of injury) (2): Injury located near a surgically closed viscus, such as bowel or vagina

Patient is being re-explored for other reasons

Campbell's 11th edition: postoperatively discovered injuries should be immediately repaired when detected within 72 hours.

Endoscopic injury: ureteral stent +/- percutaneous nephrostomy tube Ureteral perforation during ureteroscopy can be treated by ureteral stenting, usually with no subsequent complications

If endoscopic or percutaneous procedures are not possible or fail to adequately divert the urine, open or laparoscopic repair may be performed.

Ureterovaginal fistula: ureteral stent In females who undergo vaginal surgery (such as hysterectomy) or sustain penetrating pelvic trauma involving the vagina, an initially unrecognized ureteral injury can present in a delayed manner with ureterovaginal fistula.

Success rates range from64%-100% for ureterovaginal fistula who are initially managed with ureteral stent placement

Patients who failed with ureteral stent insertion went on to undergo ureteral reimplantation with or without Boari flap or psoas hitch, or transureteroureterostomy with success rates approaching 100%

Ligation of the ureter: removal ligature and observe the ureter for viability If viability uncertain, perform ureteroureterostomy or ureteral reimplantation

Ureteroarterial fistula A rare and potentially catastrophic condition that should be diagnosed and treated immediately because it can cause life-threatening hematuria

Principles of managing the injured ureter: Mobilize the injured ureter, sparing the adventitia widely, so as not to devascularize the ureter further

Debride the ureter minimally but judiciously until edges bleed, especially in gunshot wounds

Repair ureters with spatulated, tension-free, stented, watertight anastomosis, using fine absorbable monofilament such as 5-0 polydioxanone (PDS) and retroperitoneal drainage afterward. Use optical magnification if necessary.

Retroperitonealize the ureteral repair by closing peritoneum over it if possible

Do not tunnel ureteroneocystostomies but rather create a widely spatulated nontunneled anastomosis

With severely injured ureters, blast effect, concomitant vascular surgery, and other complex cases, consider omental interposition to isolate the repair when possible

Surgical management See Surgical repair section in Management of Upper Urinary Tract Obstruction Chapter Notes

Options for repair/reconstruction, choice depends on location and length of injury Upper ureteral injuries (above iliac vessesls) Ureterocalycostomy

Ureter-ureterostomy

Trans-ureterostomy

Ileal or other interposition (not recommended in acute setting)

Autotransplant (not recommended in acute setting)

Rarely, acute nephrectomy is required to treat ureteral injury after external violence

Lower ureteral injuries (below iliac vessesls) Ureteroneocystostomy

Psoas hitch

Boari flap

Follow-up after repair 6 weeks: remove stent At the time of stent removal, retrograde ureterogram can be perform to document healing without leakage or stenosis.

10 weeks: furosemide (Lasix) renogram can document that the system continues to be unobstructed.

4 months: renal US can document lack of hydronephrosis, which itself might indicate late obstruction

Questions

Describe the 2018 AAST Kidney Injury Scale

What are physical exam findings suggestive of renal trauma?

As per the 2020 AUA Guidelines on Urotrauma, what are the indications for imaging in suspected renal trauma?

What is the imaging of choice is suspected renal trauma?

What is the management of renal trauma? With/without urinary extravasation?

When is follow-up imaging indicated in renal trauma?

What findings on CTU are suggestive of ureteral injury?

What is the management of an unstable patient found to have ureteral injury intra-operatively?

What is the management of ureteral contusion following gun shot wound?

What are the surgical options to treat a penetrating ureteral injury following a stab wound?

What are CT findings suggestive of significant renal injury?

What factors are associated with increased need for intervention in grade 3 and 4 injuries?

What are the indications for intervention in renal trauma?

Which procedure is associated with the highest risk of ureteric injury?

What are contraindications to IV methylene blue?

List signs and symptoms associated with missed ureteral injury

What is the timing of repair of a ureteric injury?

What are the management options in an unstable patient with ureteric injury?

Answers

Describe the 2018 AAST Kidney Injury Scale Grade I: subcapsular hematoma and/or parenchymal contusion without laceration

Grade II: renal parenchymal laceration ≤1 cm depth without urinary extravasation OR perirenal hematoma within Gerota fascia

Grade III: renal parenchymal laceration >1 cm depth without collecting system rupture or urinary extravasation OR any injury in the presence of a kidney vascular injury or active bleeding contained within Gerota fascia

Grade IV: parenchymal laceration extending into urinary collecting system with urinary extravasation OR renal pelvis laceration and/or complete ureteropelvic disruption OR active bleeding beyond Gerota fascia into the retroperitoneum or peritoneum OR segmental renal vein or artery injury OR segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding

Grade V: main renal artery or vein laceration or avulsion of hilum OR devascularized kidney with active bleeding OR shattered kidney with loss of identifiable parenchymal renal anatomy

What are physical exam findings suggestive of renal trauma? Flank bruising

Broken ribs

Hematuria

As per the 2020 AUA Guidelines on Urotrauma, what are the indications for imaging in suspected renal trauma? Gross hematuria

Microscopic hematuria and systolic blood pressure < 90mmHG

Mechanism of injury concerning for renal injury

Physical exam findings concerning for renal injury

Penetrating injury

What is the imaging of choice is suspected renal trauma?

CT with IV contrast with immediate and delayed images

What is the management of renal trauma? With/without urinary extravasation? In hemodynamically stable patients with renal injury, non-invasive management is preferred

In hemodynamically unstable patients, immediate intervention (surgery or angioembolization) is required

In patients with urinary extravasation due to suspected Parenchymal collecting system injuries, a period of observation without intervention is advocated in stable patients where renal pelvis or proximal ureteral injury is not suspected

Renal pelvis or proximal ureteral avulsion (e.g., a large medial urinoma or contrast extravasation on delayed images without distal ureteral contrast), prompt intervention is required

When is follow-up imaging indicated in renal trauma?

AAST Grade IV-V injury, should be done after 48 hours

Clinical signs complications (e.g., fever, worsening flank pain, ongoing blood loss, abdominal distention).

What findings on CTU are suggestive of ureteral injury? Contrast extravasation

Ipsilateral delayed pyelogram

Ipsilateral hydronephrosis

Lack of contrast in the ureter distal to the suspected injury

What is the management of an unstable patient found to have ureteral injury intra-operatively?

Ureteral ligation followed by percutaneous nephrostomy tube insertion OR externalized ureteral catheter secured to the proximal end of the ureteral defect with delayed repair of the injury when patient stable

What is the management of ureteral contusion following gun shot wound?

Ureteral stenting OR resection and primary repair depending on ureteral viability and clinical scenario

What are the surgical options to treat a penetrating ureteral injury following a stab wound?

Injury above the iliac vessels: resection of non-viable ureteral tissue followed by uretero-ureterostomy over a ureteral stent; adjunct procedures (psoas hitch, Boari flap) may be needed

Below iliac vessels: ureteral reimplantation or uretero-ureterostomy over a stent

References

Morey, Allen F., et al. "Urotrauma guideline 2020: AUA guideline." The Journal of urology 205.1 (2021): 30-35.

Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 50