imaging in renal trauma presented by: dr. ajay p dsouza senior specialist radiologist dasman...

IMAGING IN RENAL TRAUMA

Presented by: Dr. Ajay P DsouzaSenior Specialist Radiologist Dasman Diabetes Institute.

Supervised by Dr. Abdelmohsen Bennakhi

FFR-RCSI FCSR-McMaster-Canada

FFR-RCSI Course Director-KIMSConsultant Radiologist-MAK Hospital

Presented at: Sabah Al Ahmed Urology Center

13.02.2014 Kuwait.

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

Mechanism of Renal trauma

Motor vehicle collision (MVC)

Fall from height, Direct blow to the

torso Sports injury

Deceleration injury

Imaging anatomy of Kidney

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.

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 

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

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 leakLow sensitivity for retroperitoneal blood.

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.

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

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

BA

C D

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.

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

Reporting terminology used in CT1. 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.

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

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

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

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

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.

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

FIGURE 1

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)

FIGURE 2

Source: Urology 2003; 61:224

8. Active arterial extravasation

Focal ill defined areas of

contrast leak with different

configurations with high

attenuation values(85-370

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

Active arterial haemorrhage in a patient in marginally unstable condition.

Harris A C et al. Radiographics 2001;21:S201-S214©2001 by Radiological Society of North America

Active haemorrhage

Dinkel H et al. Radiology 2002;223:723-730©2002 by Radiological Society of North America

Active haemorrhage in a 35-year-old man who sustained left flank penetrating trauma from a stab wound.

Alonso R C et al. Radiographics 2009;29:2033-2053©2009 by Radiological Society of North America

9.Devascularized kidney

Diffuse non-perfusion of kidney Most often from a clot that forms in an

incompletely torn renal artery

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

 Avulsion of the ureteropelvic junction in a 49-year-old man who had sustained blunt trauma.

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

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.

AAST Renal Injury Scale -1989

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.

AAST: new versus old

2011

1989

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

repairPartial PUJ avulsion treated with

interventional radiology techniques

Renal artery thrombosis and devascularization -thrombolysis or

stenting within few hours

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

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

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.

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.

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.

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.

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.

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

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

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

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.

Case 10

Splenic laceration with perisplenic and perinephric hematoma and left partial

PUJ avulsion- Grade 4 injury

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

Case 12

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

Case 13 ?

Suspicious of Grade 4 injury – Needs a delayed excretory phase image

 Multiple renal lacerations in a 9-year-old boy who had sustained blunt abdominal trauma and intra-abdominal injury. Grade 4 with active bleed

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

Case 14

FCT scan shows capsular rim nephrogram in the left kidney (arrows) after a renal infarction.

Harris A C et al. Radiographics 2001;21:S201-S214©2001 by Radiological Society of North America

Case 15

Alonso R C et al. Radiographics 2009;29:2033-2053©2009 by Radiological Society of North America

Case 16a

Alonso R C et al. Radiographics 2009;29:2033-2053©2009 by Radiological Society of North America

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.

Alonso R C et al. Radiographics 2009;29:2033-2053©2009 by Radiological Society of North America

Case 16c

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

Case 17a

Traumatic occlusion of the main renal artery in a 17-year-old boy who had sustained blunt abdominal trauma.

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

Case 17b

Traumatic occlusion of the main renal artery in a 38-year-old man who had sustained blunt abdominal trauma.

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

Case 17c

Laceration of the renal vein in an 18-year-old woman who had sustained blunt abdominal trauma. Grade 5 injury

Kawashima A et al. Radiographics 2001;21:557-574©2001 by Radiological Society of North America

Case 18

Case 19

Fractured kidney with PCS injury and urinoma

Case 20

Pseudo aneurysm of segmental renal artery

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,

Thank you