Editing Upper Urinary Tract Trauma (section)

== Renal Trauma ==

=== Epidemiology ===

* '''<span style="color:#ff0000">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):''' 
**# '''Immature, more pliable thoracic cage'''
**# '''Weaker abdominal musculature'''
**# '''Less perirenal fat''' 
**# '''Sits in a lower abdominal position'''

=== Diagnosis and Evaluation ===

==== History and Physical Exam ====

===== History =====

* '''<span style="color:#ff0000">Extent of deceleration''' involved in high-velocity impact trauma
**'''<span style="color:#ff0000">Most important information in blunt renal injury'''
* '''<span style="color:#ff0000">Trauma anterior vs. posterior to the axillary line'''
**'''<span style="color:#ff0000">Trauma anterior to axially 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 =====

* '''<span style="color:#ff0000">Findings indicating possible renal injury (5):'''

# '''<span style="color:#ff0000">Flank hematoma'''
# '''<span style="color:#ff0000">Abdominal or flank tenderness'''
# '''<span style="color:#ff0000">Rib fractures''' 
#* Ipsilateral rib fracture can increase the incidence of significant renal trauma by 3x
# '''<span style="color:#ff0000">Hematuria'''
#* '''<span style="color:#ff0000">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
#'''<span style="color:#ff0000">Penetrating injuries to the low thorax or flank'''

==== Imaging ====

===== Indications =====
* '''<span style="color:#ff0000">[https://pubmed.ncbi.nlm.nih.gov/33053308/ 2020 AUA Urotrauma Guidelines]'''
**'''<span style="color:#ff0000">Indications for imaging (contrast enhanced CT with immediate and delayed films) in stable trauma patients (5):''' 
**# '''<span style="color:#ff0000">Gross hematuria''' 
**# '''<span style="color:#ff0000">Microscopic hematuria and systolic blood pressure < 90mmHG'''
**# '''<span style="color:#ff0000">Mechanism concerning for renal injury (e.g., rapid deceleration, significant blow to flank)'''
**# '''<span style="color:#ff0000">Physical exam findings concerning for renal injury (e.g. rib fracture, significant flank ecchymosis)''' 
**# '''<span style="color:#ff0000">Penetrating injury of abdomen, flank, or lower chest''' 
*** '''<span style="color:#ff0000">Generally, children can be imaged using the same criteria as adults. Children, however, often do not exhibit hypotension as adults do.'''

===== Modality =====
* '''<span style="color:#ff0000">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
** In rare cases where the patient is taken to the operating room without preliminary CT scan and surgeons are considering renal exploration or nephrectomy, 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
** '''<span style="color:#ff0000">Major limitation of CT scan in renal trauma: inability to adequately define a renal venous injury adequately.''' 
*** '''<span style="color:#ff0000">A medial hematoma strongly suggests a venous injury, however, there is no imaging modality which can accurately diagnose a venous injury'''

===== Findings =====
*'''<span style="color:#ff0000">CT findings suspicious for significant renal injury include (6):''' 
*# '''<span style="color:#ff0000">Medial laceration'''
*# '''<span style="color:#ff0000">Medial hematoma (vascular pedicle injury)'''
*# '''<span style="color:#ff0000">Medial urinary extravasation (renal pelvis or ureteropelvic junction injury)'''
*# '''<span style="color:#ff0000">Hematoma > 3.5cm'''
*# '''<span style="color:#ff0000">Lack of contrast enhancement of the parenchyma (main renal arterial injury)'''
*# '''<span style="color:#ff0000">Active intravascular contrast extravasation (arterial injury with brisk bleeding)'''
[[File:Leftrenalarteryinjury.png|center|thumb|600x600px|Axial CT scan with contrast, red arrow showing left renal artery injury with extravasation. [[commons:File:Leftrenalarteryinjury.png|Source]]]] 

* '''<span style="color:#ff0000">Differential diagnosis of fluid collections seen on serial imaging for renal trauma (3):'''

# '''<span style="color:#ff0000">Hematoma''' - density is almost always > 30 HU
# '''<span style="color:#ff0000">Urinoma''' - density ranges from 0-20 Hounsfield units (HU)
# '''<span style="color:#ff0000">Abscess''' - associated with rim enhancement; perinephric abscess rarely occurs after renal injury

==== Grading ====

==== [https://www.aast.org/resources-detail/injury-scoring-scale#kidney AAST Grading] ====
 {| class="wikitable"
|'''<span style="color:#ff0000">Grade'''
|'''<span style="color:#ff0000">Imaging criteria (CT findings)'''
|-
|'''<span style="color:#ff0000">I'''
|
* '''Subcapsular hematoma and/or parenchymal <span style="color:#ff0000">contusion</span> without laceration'''
|-
|'''<span style="color:#ff0000">II'''
|
* '''Perirenal hematoma confined to Gerota fascia'''
* '''Parenchymal <span style="color:#ff0000">laceration ≤1 cm depth without urinary extravasation'''
|-
|'''<span style="color:#ff0000">III'''
|
* '''Parenchymal <span style="color:#ff0000">laceration >1 cm depth without collecting system rupture or urinary extravasation'''
* '''<span style="color:#ff0000">Any injury in the presence of a kidney vascular injury (pseudoaneurysm or AV fistula) or active bleeding contained within Gerota fascia'''
|-
|'''<span style="color:#ff0000">IV'''
|
* '''Parenchymal <span style="color:#ff0000">laceration extending into urinary collecting system with urinary extravasation'''
* '''<span style="color:#ff0000">Active bleeding beyond Gerota fascia</span> into the retroperitoneum or peritoneum'''
* '''<span style="color:#ff0000">Renal pelvis laceration and/or complete ureteropelvic disruption'''
* '''<span style="color:#ff0000">Segmental renal vein or artery injury'''
* '''<span style="color:#ff0000">Segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding'''
|-
|'''<span style="color:#ff0000">V'''
|
* '''<span style="color:#ff0000">Main renal artery or vein laceration or avulsion of hilum'''
* '''<span style="color:#ff0000">Devascularized kidney</span> with active bleeding'''
* '''<span style="color:#ff0000">Shattered kidney</span> with loss of identifiable parenchymal renal anatomy'''
|}
<nowiki>*</nowiki>Advance one grade for bilateral injury up to grade III
[[File:Abdotrauma.png|center|thumb|600x600px|What Grade of injury is this based on the AAST classification? [[commons:File:Abdotrauma.PNG|Source]]]]

=== 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

==== <span style="color:#ff0000">Indications for intervention</span> ====
* '''<span style="color:#ff0000">[https://pubmed.ncbi.nlm.nih.gov/33053308/ 2020 AUA Urotrauma Guidelines]</span>'''
**'''<span style="color:#ff0000">Approach based on based on hemodynamic stability</span>'''
*** '''<span style="color:#ff0000">If hemodynamically stable: non-invasive management</span>'''
**** '''<span style="color:#ff0000">Non-invasive management includes (4):'''
****#'''<span style="color:#ff0000">Close hemodynamic monitoring'''
****#'''<span style="color:#ff0000">Bed rest'''
****#'''<span style="color:#ff0000">ICU admission'''
****#'''<span style="color:#ff0000">Blood transfusion (when indicated)'''
****#'''<span style="color:#ff0000">Imaging (when indicated)</span>'''
****#*'''<span style="color:#ff0000">Indications for follow-up CT imaging (after 48 hours) in renal trauma patients (2):</span><span style="color:#ff0000">[https://pubmed.ncbi.nlm.nih.gov/33053308/ ★]'''
****#*#'''<span style="color:#ff0000">Clinical signs of complications (e.g., fever, worsening flank pain, ongoing blood loss, abdominal distention)</span>'''
****#*# '''<span style="color:#ff0000">Deep lacerations (AAST Grade IV-V)</span>'''
****#*#*AAST Grade IV-V renal injuries are prone to developing troublesome complications such as urinoma or hemorrhage
****#*#*AAST Grade I-III injuries have a low risk of complications and rarely require intervention. Routine follow-up CT imaging is not advised for uncomplicated AAST Grade I-III injuries because it is not likely to change clinical management in these cases
****'''<span style="color:#ff0000">Patients initially managed noninvasively may still require treatments (surgical, endoscopic, or angiographic) at a later time, especially those with higher grade injuries.'''
*****'''<span style="color:#ff0000">Factors associated with increased risk of bleeding and need for intervention in grade 3 and 4 injuries (3):</span>'''
*****#'''<span style="color:#ff0000">Medial hematoma</span>'''
*****#'''<span style="color:#ff0000">Hematoma > 3.5-4 cm in thickness</span>'''
*****#'''<span style="color:#ff0000">Presence of a contrast extravasation from vessels on imaging</span>'''
*****Although devitalized parenchyma has been suggested as a risk factor for development of septic complications, evidence supporting intervention for this radiographic finding is inconclusive
****Delayed renal bleeding can occur up to several weeks after injury but usually occurs within 21 days.
***'''<span style="color:#ff0000">If hemodynamically unstable: immediate intervention (surgery or selective angioembolization)</span>'''
**** '''<span style="color:#ff0000">Perform immediate intervention 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)[https://pubmed.ncbi.nlm.nih.gov/33053308/ ★]'''
***** 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
****'''<span style="color:#ff0000">Patients who are hemodynamically unstable despite active resuscitation should be taken to the operating room rather than angiography'''
* '''[https://pubmed.ncbi.nlm.nih.gov/31827593/ 2019 World Society of Emergency Surgery (WSES) and the American Association for the Surgery of Trauma (AAST) Guidelines]'''
** '''Non-operative management should be the treatment of choice for all hemodynamically or stabilized patients'''
**'''Isolated urinary extravasation, in itself, is not an absolute contra-indication to non-operative management in absence of other indications for laparotomy.''' 
**'''Hemodynamic stable or stabilized patients having damage to the renal pelvis not amenable to endoscopic/percutaneous techniques/stent should be considered for delayed OM in absence of other indications for immediate laparotomy.'''
**'''Hemodynamically unstable or non-responders to resuscitation should undergo operative management'''

==== <span style="color:#ff0000">Surgical management</span> ====
*Nephrectomy is a frequent result when hemodynamically unstable patients undergo surgical exploration
*'''<span style="color:#ff0000">Approach: transabdominal</span>'''
**'''Allows complete inspection of intra-abdominal organs and bowel.'''
*'''<span style="color:#ff0000">Principles of renal reconstruction after trauma include (8):</span>'''
*#'''Complete renal exposure'''
*#'''Measures for temporary vascular control'''
*#*'''<span style="color:#ff0000">Isolate the renal vessels before exploration</span> to provide the immediate capability to occlude them if massive bleeding should ensue when the Gerota fascia is opened'''
*#'''Limited debridement of nonviable tissue'''
*#'''Hemostasis by individual suture ligation of bleeding vessels'''
*#'''Watertight closure of the collecting system if necessary/possible'''
*#'''Reapproximation of the parenchymal defect'''
*#'''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.
*#'''Liberal use of drains'''
*'''<span style="color:#ff0000">For major renovascular injuries in patients with 2 kidneys, speedy nephrectomy is advocated</span>'''
**In rare instances in which vascular repair is technically feasible, renal salvage rates are disappointingly low
*'''<span style="color:#ff0000">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.</span>'''
**This allows the cold, acidotic, and coagulopathic patient to be stabilized in the ICU before any attempt at potentially lengthy renal reconstruction is attempted.
*'''<span style="color:#ff0000">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.</span>'''

==== Special Scenarios ====
===== Renal injury with urinary extravasation =====
*'''<span style="color:#ff0000">Persistent urinary extravasation can result in:'''
*#'''<span style="color:#ff0000">Urinoma'''
*#'''<span style="color:#ff0000">Perinephric infection'''
*#'''<span style="color:#ff0000">Renal loss (rarely)'''
*'''Stable patients where renal pelvis or proximal ureteral injury is not suspected: observation (AUA)'''
**'''Parenchymal collecting system injuries often resolve spontaneously.'''
***Urinary extravasation alone from a grade IV parenchymal laceration or forniceal rupture managed non-operatively has a spontaneous resolution of > 90%
*'''<span style="color:#ff0000">Indications for intervention (4):</span>'''
*#'''<span style="color:#ff0000">Suspected injury to renal pelvis or proximal ureteral avulsion</span>'''
*#*'''<span style="color:#ff0000">Suggested by large medial urinoma or contrast extravasation on delayed images without distal ureteral contrast</span>'''
*#*'''Management is either endoscopic or open depending on the clinical scenario'''
*#'''<span style="color:#ff0000">Urinoma increasing in size, purulence, or complexity</span> on follow-up imaging'''
*#'''<span style="color:#ff0000">Presence of complications such as fever, infection, increasing pain, ileus, or fistula.</span>'''
*# '''Severe renal injuries with <span style="color:#ff0000">continued urinary extravasation</span>''' (not described in 2020 AUA Guidelines)
*#*'''Placement of an internal ureteral stent for drainage may prevent prolonged urinary extravasation and decrease the chance of perirenal urinoma formation'''
* '''<span style="color:#ff0000">Options for intervention'''
*#'''<span style="color:#ff0000">Ureteral stent (preferred)'''
*#*An internalized ureteral stent is minimally invasive and alone may provide adequate drainage of the injured kidney
*#*'''A period of concomitant Foley catheter drainage may minimize pressure within the collecting system and enhance urinoma drainage'''
*# '''Percutaneous urinoma drain, percutaneous nephrostomy, or both may also be necessary'''

===== <span style="color:#ff0000">Hypertension and Renal Trauma</span> =====
*'''Hypertension is rarely noted in the early postinjury period but can occur later.'''
*'''<span style="color:#ff0000">Mechanisms for hypertension as a complication of renal trauma (4):</span>'''
*#'''<span style="color:#ff0000">Renal vascular injury, leading to stenosis or occlusion of the main renal artery or one of its branches</span>''' (one-clip, Goldblatt kidney)
*#'''<span style="color:#ff0000">Page kidney: compression of the renal parenchyma with extravasated blood or urine</span>'''
*#'''<span style="color:#ff0000">Post-trauma arteriovenous fistula</span>'''
*#'''<span style="color:#ff0000">Ureteral / UPJ obstruction</span>[https://www.ncbi.nlm.nih.gov/pubmed/29959876]'''
*#*In the first 3 scenarios, the renin-angiotensin axis is stimulated by partial renal ischemia, resulting in hypertension
* '''Can be treated with (3):'''
*#'''Anti-hypertensives'''
*#'''Observation'''
*#'''Nephrectomy (uncommonly)'''