1. IMAGING IN RENAL TRAUMA
Presented by: Dr. Ajay P Dsouza
Senior Specialist Radiologist
Dasman Diabetes Institute.
Supervised by
Dr. Abdelmohsen Bennakhi
FFR-RCSI
FCSR-McMaster-Canada
FFR-RCSI Course Director-KIMS
Consultant Radiologist-MAK Hospital
Presented at:
Sabah Al Ahmed Urology Center
Kuwait.

2. Learning objectives Describe the mechanism of renal injuries
Indications for imaging in renal trauma.
Describe the spectrum of renal injuries.
Identify the key imaging features on CT.
Correlate the imaging findings with AAST grading.
Identify the distinguishing CT features according to the AAST grading.
Update with modifications of AAST Renal Injury Grades.
Role of interventional radiology in the management of Renal injury

3. Mechanism of Renal trauma
Motor vehicle collision (MVC)
Fall from height,
Direct blow to the torso
Sports injury
Deceleration injury

4. Renal Injury : Epidemiology
Injury to the kidney is seen in 8%–10% of patients with blunt or penetrating abdominal injuries.
The vast majority (80%–90%) are blunt rather than penetrating injury.
Serious renal injuries are frequently associated with injuries to other organs.
Multi-organ involvement occurs in 80% of patients with penetrating trauma and in 75% of those with blunt trauma.
The vast majority (98%) of isolated renal injuries are classified as minor injuries 

5. Imaging anatomy of Kidney

6. The anterior pararenal space (APRS) is located between the parietal peritoneum (PP) and the anterior renal fascia (ARF) and contains the pancreas (Pan),the ascending colon (AC), and the descending colon(DC). 
The posterior pararenal space (PPRS) is located between the posterior renal fascia (PRF) and the transversalis fascia (TF). 
The perirenal space (PRS) is located between the anterior renal fascia and the posterior renal fascia. 
Ao = aorta, IVC = inferior vena cava, LCF = lateroconal fascia.

7. Clinical Features of Renal Trauma
Gross or microscopic hematuria (absent in 5%)
Flank pain / ecchymosis
Hemodynamic instability
Presence of other abdominal injuries

8. Indications for Imaging
Universally accepted indications for renal imaging in blunt trauma include 
Gross hematuria
Microscopic hematuria and hypotension (systolic blood pressure <90 mm Hg) or other associated injuries requiring CT evaluation
Blunt trauma with other injuries known to be associated with renal injury (e.g. rapid deceleration, fall from a height, direct contusion or hematoma of flank soft tissues, fractures of the lower ribs or thoracolumbarspine),regardless of the presence of hematuria 

9. Role of Imaging Ultrasound
Quick, non invasive low cost way of detecting peritoneal fluid (FAST)
Can detect renal laceration but not accurate in depth and extent
No functional information like leakage and excretion
Can be better for the follow up and checking resolution of hematomas
For triage of patients with blunt trauma.
Operator dependent

10. FAST Extension of physical examination of the trauma patient
Can be done during primary survey
Primary goal of FAST is to identify intraabdominal free fluid.
Free fluid=Hemoperitoneum in unstable patients
Free fluid found – solid organ injury in 80-90%
Draw back:
Blood versus extravasated fluid /urine leak
Low sensitivity for retroperitoneal blood.

11. Role of FAST
Hemodynamic instability in patients with positive FAST results warrants surgical exploration, whereas indeterminate FAST results lead to a complete repeat US or CT examination
Hemodynamically stable patients with positive or indeterminate FAST results should undergo CT examination
Hemodynamically stable patients with negative FAST results may be followed up with clinical observation of at least 6 hours duration and with repeat FAST or a complete US examination to confirm the absence of injury.
©2009 by Radiological Society of North America

12. Intravenous Pyelography
Replaced by CT
Recommended in places where only IVP is available
One shot intra-operative IVP
In unstable patients with signs of renal injury who undergo immediate operative intervention it provides important information for decision making as to the function of the kidney and renal injury
Iodinated contrast of 2ml/kg body weight followed by plain film after 10 minutes, it is safe and efficient.

13. Contrast Computed Tomography
Gold standard method
Most sensitive and specific than IVP
Detects all grades of injuries
Gives overview of the abdomen and pelvis
Superior anatomical detail and fast
Detects associated injuries
Urography phase gives functional details.
Missed renal injury on CT is common but minor and do not alter clinical course

14. CECT technique
Goal is largest amount of information in the shortest possible time
Initial nonenhanced study can be helpful in detecting acute bleeding or intraparenchymal hematoma that may become isoattenuating relative to the normal renal parenchyma at post contrast CT
Routine CT usually includes a portal venous phase; therefore, the kidneys will be imaged during the late cortical or early nephrographic phase, which allows identification of parenchymal injuries
Imaging should be performed during excretory phase (5min) to rule out leakage of contrast-enhanced urine if renal pedicle injury or significant perinephric or periureteral fluid is found, and whenever confusing findings requiring further characterization are depicted during the portal venous phase
Delayed CT may also be useful in distinguishing between active bleeding and pseudo aneurysms

15. B A C D

16. MRI Not used routinely Longer imaging time
Used when CT not available/ iodine allergy
In few cases were CT findings are equivocal.
Technically demanding on patient and facility.

17. Angiography
Stable patients who are candidates for radiological control of hemorrhage defined on CT
More specific than CT in defining vascular injury
Renal vein injury
Non enhancing Kidney on CT

18. Blunt trauma algorithm

20. Penetrating trauma algorithm

21. Reporting terminology used in CT
1. Contusions: is described as an ill-defined and poorly marginated hypo dense area of decreased enhancement on the nephrographic phase that may show delayed or persistent enhancement.

22. 2. Infarction
Infarcts are wedged shaped sharply marginated hypo dense area seen on the nephrographic phase and shows no delayed enhancement.
Infarcts can be confused with Contusions

23. 3. Subcapsular Hematoma
Subcapsular hematomas are seen as cresentic or biconvex area of blood collection along the renal contour causing flattening or depression of the underlying renal surface

24. 4.Perinephric hematoma
Perinephric hematoma is confined between the renal parenchyma and Gerota's Fascia
It outlines renal contour extending over a wider area with (when large) without flattening or depression of renal margins. It can displace the kidney.
It occurs following a laceration of the renal capsule

25. 5.Laceration
Lacerations are irregular linear hypo dense areas of parenchymal defect reaching up to surface causing disruption of the parenchymal continuity
It may be complex with variable width of the clefts that may be filled with blood clots
They also show no enhancement

26. 6.Shattered Kidney
Multiple lacerations causing gross disruption and fragmentation of the renal parenchyma often associated with renal function compromise, injury to the collecting system with urinary extravasation, severe hemorrhage and active arterial bleeding.

27. 7.Pseudo aneurysm
Focal rounded well circumscribed lesion within the renal parenchyma or in the lacerated segment that shows intense enhancement similar to that of the attenuation of the blood pool and wash out synchronous to blood pool
There is no expansion on the delayed scans
Pseudo aneurysm

28. FIGURE 1
Contrast-enhanced CT scan showing intraparenchymal renal artery pseudoaneurysm (white arrow). Perirenal hematoma is also demonstrated with increased density due to fresh bleeding.
Renal pseudoaneurysm after blunt renal trauma in a pediatric patient: management by angiographic embolization
S Halachmi, P Chait, J Hodapp, D.G Bgli, G.A McLorie, A.E Khoury and W Farhat Urology Volume 61, Issue 1, Page 224 (January 2003)

29. FIGURE 2
Selective renal artery angiography demonstrating a pseudoaneurysm of the mid-segment artery, with preservation of arterial supply to the upper half and lower pole of kidney.
Source: Urology 2003; 61:224

30. 8. Active arterial extravasation
Focal ill defined areas of contrast leak with different configurations with high attenuation values( HU) on early scans and will appear as more hyper attenuating than blood pool and show spread and expansion in to surrounding tissue on a delayed scans

31. Active arterial haemorrhage in a patient in marginally unstable condition.
Figure 8.  Active arterial hemorrhage in a patient in marginally unstable condition. CT scan reveals a serpentine collection of vascular contrast material (arrow) within a large tissue-attenuation hematoma posterior to the right kidney. The diagnosis of arterial bleeding rather than caliceal rupture with urine leakage was predicated on the patient’s clinical status and the complete absence of fluid-attenuation, unopacified urine in the perirenal space. The patient became hypotensive during CT and underwent partial nephrectomy.
©2001 by Radiological Society of North America
Harris A C et al. Radiographics 2001;21:S201-S214

32. Active haemorrhage
Figure 4a.Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.
©2002 by Radiological Society of North America
Dinkel H et al. Radiology 2002;223:

33. Active haemorrhage in a 35-year-old man who sustained left flank penetrating trauma from a stab wound.
Active hemorrhage in a 35-year-old man who sustained left flank penetrating trauma from a stab wound. Portal venous phase CT scans show a deep laceration in the anterior aspect of the left kidney with a blood clot filling the parenchymal gap (arrow in a). A left retroperitoneal hematoma is also seen (*). Note the presence of a flame-shaped hyperattenuating focus adjacent to the renal hilum (arrow in b), a finding that is consistent with active bleeding. Maximum-intensity-projection images showed no evidence of vascular pedicle injury and no urine leakage. The patient underwent urgent nephrectomy, and the gross surgical specimen showed renal hilum injury with severe active bleeding.
©2009 by Radiological Society of North America
Alonso R C et al. Radiographics 2009;29:

34. 9.Devascularized kidney
Diffuse non-perfusion of kidney
Most often from a clot that forms in an incompletely torn renal artery

35. 10.PUJ avulsion
Occurs due to sheering injury at the fixation point as it gets stretched over the transverse process
Partial / complete
In complete avulsion no ureter is opacified on delayed images

36.  Avulsion of the ureteropelvic junction in a 49-year-old man who had sustained blunt trauma.
Figure 24c.  Avulsion of the ureteropelvic junction (category IV) in a 49-year-old man who had sustained blunt trauma. (a, b) Contrast-enhanced nephrographic-phase helical CT scans (a obtained at a higher level than b) through the lower pole of the right kidney demonstrate a perinephric fluid collection with no renal laceration. (c, d) Contrast-enhanced excretory-phase CT scans (c obtained at a higher level than d) demonstrate medial contrast material extravasation (arrow). No ureteral contrast material filling is noted. The patient underwent exploratory laparotomy for a mesenteric laceration. A diagnosis of ureteropelvic junction avulsion was made, and primary surgical repair of the ureter was performed.
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

37. Summary of Radiology Key findings
Terminology
How do you recognize it
Contusion (75-80%)
Focal patchy areas of decreased enhancement
Laceration
Irregular linear hypo dense parenchymal areas
Fracture
Laceration connecting two cortical surfaces
Shattered Kidney
Multiple separated renal fragments ± perfusion /excretion
Calyceal or pelvic injury
Extraluminal contrast on delayed
Vascular pedicle injury
Wedge-shaped or diffuse non-perfusion of kidney
Subcapsular hematoma
Superficial crescentic hypodense area compressing adjacent parenchyma

38. AAST grading of the Renal Injury
Common consensus grading for renal injuries between radiologists and surgeons
Abdominal CT or direct renal exploration is used to accomplish injury classification
Now it is a standard method adopted for radiological reporting.

39. AAST Renal Injury Scale -1989

40. AAST Renal Injury Scale - 2011
Grades I, II, and III remain unchanged.
Grades IV and V are updated as follows:
Grade IV
Originally encompassed contained injuries to the main renal artery and vein, and collecting system injuries.
Revision: adds segmental arterial and venous injury, and laceration to the renal pelvis or ureteropelvic junction. Multiple lacerations into the collecting system used to be considered a shattered kidney (Grade V), but now remains Grade IV.
Grade V
Originally included main renal artery or vein laceration or avulsion, and multiple collecting system lacerations (shattered kidney).
Revised classification includes only vascular injury (arterial or venous) and includes laceration, avulsion or thrombosis.
Revision of current American Association for the Surgery of Trauma renal injury grading system. J Trauma 70(1):35-37, 2011.

41. 1989
AAST: new versus old
2011

42. Renal trauma management Interventional radiological perspective
CT Classification of Renal Trauma
Grade
Usual management
Remarks
Grade 1,2,3
Conservative
Management
Intervention needed in presence of active hemorrhage with angio-embolization/ Surgery in those with hemodynamic instability
Grade 4
Trial of conservative management provided the patient is hemodynamically stable with no expanding hematoma
PCS injury managed with interventional radiology techniques
Grade 5
Complete PUJ disruption and renal pedicle avulsion needs surgical repair
Partial PUJ avulsion treated with interventional radiology techniques
Renal artery thrombosis and devascularization -thrombolysis or stenting within few hours

43. Follow up imaging Needed to look for the resolution of injury
Usually not indicated for Grade 1-3 and grade 4 renal injuries without urinary extravasation
Grade 4 injuries with urinary leak on previous scan
Grade 5 renal injuries who were managed conservatively
Patients with complications( fever, fall in HCT or clinical instability)
Associated co-morbidity

44. Complications after renal trauma
3-10% of cases.
Early complications
Urinoma –most common
Delayed bleeding -1-2 weeks
Urinary fistula
Abscess and hypertension
Late complications
Hydronephrosis
Arteriovenous fistula
Pyelonephritis
Calculus formation
Delayed hypertension

45. Case 1
Grade 1 & 2 renal injury, Subcapsular hematoma. CT scan of the abdomen with intravenous contrast in a patient after a motor vehicle collision shows cresentic high-density fluid collection around the left kidney. Note the well-defined outer margin and the mild deformity of the renal parenchyma.

46. Case 2
Grade 2 renal injury, subcapsular and perinephric hematomas. Contrast-enhanced CT scan of the abdomen on a patient with hematuria after a motor vehicle collision shows an ill-defined fluid collection in the left perinephric space. There is also a subcapsular hematoma with deformity of the renal parenchyma.

47. Case 3
Grade 2 renal laceration. Contrast-enhanced CT scan of the abdomen after a motor vehicle collision shows a superficial (less than 1 cm deep) renal parenchymal defect with a large perinephric hematoma.

48. Case 4
Grade 3 renal laceration. CT scan of the abdomen after intravenous contrast administration shows irregular nonenhancing renal parenchymal defect with extension greater than 1 cm deep to near the renal pelvis.

49. Case 5
  Renal infarction. Contrast-enhanced CT scan of the upper abdomen in another patient after a motor vehicle collision shows a segmental area of nonenhancement in the upper medial left kidney without associated renal laceration.

50. Case 6
Lacerations extending to the collecting system. Contrast-enhanced CT scan of the abdomen in a patient with hematuria after a motor vehicle collision shows deep lacerations extending into the collecting system of the right kidney. Extension into the collecting system is confirmed by urinary contrast extravasation on delayed image through the kidney in excretory phase. Grade 4 injury

51. Case 7
Shattered left kidney. Contrast-enhanced CT scan of the abdomen in a patient with hematuria after a motor vehicle collision shows several deep lacerations extending into the collecting system of the left kidney with separation of the fragments. Grade 4 injury

52. Case 8
Contrast-enhanced CT scan of the abdomen shows nonenhancement of left kidney with non opacified left renal artery and hilar fat stranding suggesting renal artery injury with thrombosis – Devascularization injury and associated left perinephric hematoma- Grade 5 injury

53. Case 9
Fracture of the left lower pole of the kidney. Contrast-enhanced CT scan of the abdomen shows non enhancement of the lower pole of left kidney. Extension into the collecting system is confirmed by urinary contrast extravasasation on delayed image through the kidney in excretory phase Grade 4 Injury.

54. Case 10
Splenic laceration with perisplenic and perinephric hematoma and left partial PUJ avulsion- Grade 4 injury

56. Case 11
Shattered right kidney with pseudo aneurysm formation. Right renal angiogram pre and post embolization of the aneurysm. Spasm of the right proximal renal artery is noted

57. Case 12
Non enhancing right kidney, perinephric hematoma and right renal artery occlusion on selective angiogram – Grade 5 injury

58. Case 13 ?
Suspicious of Grade 4 injury – Needs a delayed excretory phase image

59. Case 14
Figure 16.  Multiple renal lacerations (category III) in a 9-year-old boy who had sustained blunt abdominal trauma and intraabdominal injury. Contrast-enhanced nephrographic-phase helical CT scan shows several deep lacerations of the interpolar region of the right kidney (straight arrows) associated with areas of active arterial extravasation (curved arrows). Note the anterior displacement of the duodenum (D), pancreas (P), and inferior vena cava (V). Hemoperitoneum (H) is seen in the Morrison pouch.
 Multiple renal lacerations in a 9-year-old boy who had sustained blunt abdominal trauma and intra-abdominal injury. Grade 4 with active bleed
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

60. Case 15
Figure 15.  CT scan shows capsular rim nephrogram in the left kidney (arrows) after a renal infarction.
FCT scan shows capsular rim nephrogram in the left kidney (arrows) after a renal infarction.
©2001 by Radiological Society of North America
Harris A C et al. Radiographics 2001;21:S201-S214

61. Case 16a
Partial tear of the left ureteropelvic junction (grade IV injury) in a 50-year-old woman who was involved in a motor vehicle accident. (a) Portal venous phase CT scan shows left hydronephrosis (*) and a small amount of perinephric fluid (arrow). (b, c) Delayed excretory phase CT scans show medial perinephric urinary extravasation (arrow in b) and opacification of the distal ureter (arrowhead in c).
©2009 by Radiological Society of North America
Alonso R C et al. Radiographics 2009;29:

62. Case 16b
Partial tear of the left ureteropelvic junction (grade IV injury) in a 50-year-old woman who was involved in a motor vehicle accident. (a) Portal venous phase CT scan shows left hydronephrosis (*) and a small amount of perinephric fluid (arrow). (b, c) Delayed excretory phase CT scans show medial perinephric urinary extravasation (arrow in b) and opacification of the distal ureter (arrowhead in c).
©2009 by Radiological Society of North America
Alonso R C et al. Radiographics 2009;29:

63. Case 16c
Partial tear of the left ureteropelvic junction (grade IV injury) in a 50-year-old woman who was involved in a motor vehicle accident. (a) Portal venous phase CT scan shows left hydronephrosis (*) and a small amount of perinephric fluid (arrow). (b, c) Delayed excretory phase CT scans show medial perinephric urinary extravasation (arrow in b) and opacification of the distal ureter (arrowhead in c).
Partial tear of the left ureteropelvic junction (grade IV injury) in a 50-year-old woman who was involved in a motor vehicle accident.
©2009 by Radiological Society of North America
Alonso R C et al. Radiographics 2009;29:

65. Case 17a
Traumatic occlusion of the main renal artery in a 17-year-old boy who had sustained blunt abdominal trauma. (a) Intravenous urogram demonstrates poor visualization of the left kidney. (b) CT scan obtained without additional contrast material following urography demonstrates rim enhancement of the outer cortex of the left kidney (arrows). (c) Digital subtraction aortogram demonstrates the characteristic tapered occlusion of the proximal left main renal artery (arrow).
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

66. Case 17b
Traumatic occlusion of the main renal artery (category III) in a 17-year-old boy who had sustained blunt abdominal trauma. (a) Intravenous urogram demonstrates poor visualization of the left kidney. (b) CT scan obtained without additional contrast material following urography demonstrates rim enhancement of the outer cortex of the left kidney (arrows). (c) Digital subtraction aortogram demonstrates the characteristic tapered occlusion of the proximal left main renal artery (arrow).
Traumatic occlusion of the main renal artery in a 17-year-old boy who had sustained blunt abdominal trauma.
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

67. Case 17c
Traumatic occlusion of the main renal artery (category III) in a 38-year-old man who had sustained blunt abdominal trauma. Contrast-enhanced helical CT scan demonstrates a diminished right nephrogram. The proximal right renal artery (straight arrow) is enhanced; however, the distal main renal artery is not visualized. Note also the hepatic laceration (curved arrow) and hemoperitoneum in the Morrison pouch (H).
Traumatic occlusion of the main renal artery in a 38-year-old man who had sustained blunt abdominal trauma.
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

68. Case 18
Laceration of the renal vein (category III) in an 18-year-old woman who had sustained blunt abdominal trauma. (a) Contrast-enhanced helical CT scan demonstrates minimal perinephric hematoma without parenchymal laceration (arrows). (b) CT scan obtained 3 days later shows an interval increase in the amount of perinephric hematoma (H), resulting in deformation of the contour of the right kidney and a heterogeneously diminished nephrogram. The origin of the bleeding was not identified at CT. Laceration of the renal vein was found at surgery.
Laceration of the renal vein in an 18-year-old woman who had sustained blunt abdominal trauma. Grade 5 injury
©2001 by Radiological Society of North America
Kawashima A et al. Radiographics 2001;21:

69. Fractured kidney with PCS injury and urinoma
Case 19
Fractured kidney with PCS injury and urinoma

70. Pseudo aneurysm of segmental renal artery
Case 20
Pseudo aneurysm of segmental renal artery

72. Conclusion
Patient with hematuria after abdominal trauma should raise suspicion of renal injury
Hematuria may not be present in patients with main renal artery thrombosis or devascularized kidney
Radiology evaluation is needed to confirm and grade the injury
FAST is a rapid and well accepted tool for triage
CECT is the modality of choice to grade and look for complications.
Nephrographic phase and delayed excretory phase is needed, Be watchful about the CT phases of contrast in kidney, ask for delayed when needed.
Most renal injury can be conservatively treated
Interventional techniques and minimally invasive procedures expand the borders for conservative management and kidney salvage
Be familiar with new AAST grading,

73. Thank you