Ch.17 - Recognizing the Imaging Findings of Trauma Flashcards
Most trauma-related injuries are due to:
Blunt trauma - Motor vehicle accidents contributing the majority.
Role of CT in trauma:
Profound impact in traumatized patients by distinguished those patients who can be managed conservatively from those who need surgical or other interventions.
Rib fractures:
May herald more serious internal injuries such as lacerations of the liver or spleen or pneumothoraces.
Rib fractures - Most occur:
Ribs 4-9.
Pulmonary contusions:
MC manifestation of blunt chest trauma and represent hemorrhage into the lung, usually at the point of impact.
–> Classically clear in a few days.
Pulmonary lacerations:
- Tears in the lung parenchyma that may contain fluid or air.
- Their presence may be hidden by a surrounding contusion.
- Typically take longer than a contusion to clear.
Aortic injuries:
- Usually occur at the isthmus.
- Require rapid recognition for optimum survival.
- On contrast-enhanced CT may take the form of intimal flaps/contour/abnormalities/or hematomas.
MC affected solid organs in BLUNT abdominal trauma in order of decreasing frequency:
- Spleen.
- Liver.
- Kidney.
- Urinary bladder.
Liver injury:
- Commonly injured in BOTH blunt and penetrating trauma.
- Its injuries account for the majority of the deaths from abdominal trauma.
- May demonstrate lacerations/hematomas/wedge-shaped defects/pseudoaneurysms/acute hemorrhage.
Renal trauma:
- Almost all have hematuria.
- May show contusions, lacerations, hematomas, or vascular pedicle injuries on CT.
- May also demonstrate extraluminal contrast from an injury to the renal pelvis or ureter.
Shock bowel:
- Consequence of profound hypotension.
2. Shows diffuse small bowel wall thickening with enhancement of dilated and fluid-filled loops on CT.
Bladder ruptures:
- Either extra-peritoneal (more common) or intra-peritoneal.
- Extra-peritoneal –> Extraluminal contrast surrounding the bladder.
- Intra-peritoneal –> Showing contrast flowing freely in the peritoneal cavity.
Urethral injuries:
Almost exclusively in males
- Frequently associated with pelvic fractures.
- Usually involve the posterior urethra –> Extra-luminal contrast may be seen in the perineum or extraperitoneally in the pelvis.
Focused Abdominal Sonogram for Trauma (FAST):
- Portable US utilized on unstable trauma patients solely to identify free peritoneal fluid.
- Used primarily in place of the diagnostic peritoneal lavage.
- False negatives occur with abdominal injuries in which there is NO hemoperitoneum.
Trauma is generally divided into:
- Blunt.
2. Penetrating.
Blunt trauma usually the result of?
Motor vehicle accidents and is the more common of the two categories.
Penetrating trauma is usually the result of …?
Accidental or criminal stabbings and gunshot wounds.
Chest injuries are responsible for … out of … trauma-related deaths.
1 out of 4.
The overwhelming majority of chest traumas are the result of …?
Motor vehicle accidents.
Fractures of ribs 1-3 is …?
Relatively UNCOMMON –> Indicates a sufficient amount of force to produce other internal injuries.
Fractures of ribs 4-9 are …?
COMMON and IMPORTANT if they are displaced (pneumothorax) or if there are 2 fractures in each of three or more contiguous ribs –> flail chest.
Flail chest is almost always accompanied by …?
Pulmonary contusion –> Significant mortality.
Fractures of ribs 10-12 may indicate …?
The presence of underlying trauma to the liver (right side) or the spleen (left side), especially if they are DISPLACED.
In cases of MINOR trauma, is not unusual …?
For rib fractures to be undetectable on the initial examination but to become visible in several weeks after callus begins to form.
Pulmonary contusions are the most frequent complications of …?
Blunt chest trauma –> They represent hemorrhage into the lung –> Usually at the point of impact.
Recognizing a pulmonary contusion - What is of paramount importance?
The history of trauma.
Contusions present as airspace disease that is indistinguishable from other airspace diseases like pneumonia or aspiration.
Recognizing a pulmonary contusion - Location?
Contusions tend to be peripherally placed and frequently occur at the point of max impact.
Recognizing a pulmonary contusion - Air bronchograms?
Are usually NOT present because blood fills the bronchi as well as the airspaces.
Classically, contusions appear within …?
6 hours after the trauma.
Contusions disappear within …?
72hr, sometimes sooner –> Blood in the airspaces tends to be reabsorbed quickly.
Pulmonary hematomas result from a …?
Laceration of the lung parenchyma and, as such, may accompany more severe blunt trauma or penetrating chest trauma.
A pulmonary laceration is also called a …?
Traumatic pneumatocele or hematoma.
Recognizing a pulmonary laceration - Their appearance will depend on …?
Whether they contain blood and, if so, how much blood fills the laceration.
Recognizing a pulmonary laceration - If they are completely filled with blood …?
They will appear as a solid, ovoid mass.
Unlike pulmonary contusions that clear rapidly, pulmonary lacerations …?
May take weeks or months to completely clear.
Trauma to the aorta is most frequently the result of …?
Deceleration injuries in motor vehicles accidents.
Which patients with trauma to the aorta survive to be imaged?
Only those with incomplete tears in which the adventitial lining prevents exsanguination (producing a pseudoaneurysm).
What is the MC site of aortic injury?
The aortic isthmus.
Seat-belt injuries may involve …?
The abdominal aorta.
What is the only chance of blunt aortic injuries?
Only emergency SURGERY will prevent approx. 50% of patients with blunt aortic injuries from dying within the first 24hr if left untreated.
A NORMAL CXR has a … for aortic injury.
HIGH NEGATIVE PREDICTIVE VALUE.
AN ABNORMAL CXR has a … for aortic injury.
A relatively LOW PPV (78%).
“Widening of the mediastinum” …?
Is usually a poor means of establishing the diagnosis because it is difficult to assess on a supine, portable CXR and it is commonly OVERINTERPRETED.
Other signs that may be present in aortic injury CXR?
- Loss of normal shadow of the aortic knob.
- A left apical pleural cap of fluid or blood.
- A left pleural effusion.
- Deviation of the trachea or esophagus to the RIGHT.
Under most circumstances, suspected aortic injuries are now studied using …?
Multidetector CT that allows for rapid image acquisition in one breath-hold and appropriately timed contrast delivery to the aorta (CT angio).
The findings on CT are frequently …?
Subtle and require experience to recognize, as those patients with the more obvious findings may not have survived to be imaged.
CT findings of the chest:
- Aortic intimal flap.
- Contour or caliber abnormalities.
- Periaortic hematoma.
- Mediastinal hematoma.
- Hemopericardium.
Aortic intimal flap?
A lucent defect in the contrast column of the aorta arising from a tear in the intima and media.
Contour or caliber abnormalities?
Abrupt change in the smooth contour or size of the aorta at the point of injury.
Periaortic hematoma?
Delineation of a contrast-filled collection outside of the normal confines of the aorta –> Pseudoaneurysm or extravasation.
Mediastinal hematoma?
Increased attenuation in the mediastinum from an admixture of blood and normal fat.
–> May be present in the absence of an aortic injury, presumably due to small vessel trauma.
Hemopericardium?
Fluid of high attenuation (ie blood) in the pericardial sac indicates a significant injury to the aorta or heart itself.
Patients with equivocal CT findings may go on to a …?
Angiography - Catheter study of the aorta.
What is the study of choice in abdominal trauma?
CT.
IV contrast in abdominal CT?
ALWAYS used - Unless contraindicated.
Why do we use IV contrast in abdominal CT?
To identify:
- Devascularized areas.
- Hematomas.
- Active extravasation of blood.
- Extraluminal urine (after contrast has passed through the kidneys).
Abdominal CT - If a head CT is to be done as well …?
It should be done FIRST before contrast is injected for the abdomen.
Abdominal CT - Oral or rectal contrast?
Oral contrast is usually NOT administered.
Rectal contrast is occasionally administered in penetrating trauma to search for a bowel laceration.
What can be used in emergency setting to identify hemoperitoneum?
U/S.
The most commonly affected solid organs in BLUNT abdominal trauma (in order of decreasing frequency) are …?
- Spleen.
- Liver.
- Kidney.
- Bladder.
What is the most frequently injured organ if BOTH penetrating and blunt traumas are included together?
THE LIVER.
Injuries to the liver account for …?
The MAJORITY of deaths from abdominal trauma.
Which part of the liver is injured most frequently?
The POSTERIOR aspect of the RIGHT lobe.
Most hepatic injuries are associated with?
Hemoperitoneum.
What is the study of choice in liver trauma?
Contrast-enhanced CT.
CT findings in hepatic trauma (6)?
- Subcapsular hematoma.
- Lacerations.
- Intrahepatic hematomas.
- Wedge-shaped defects.
- Contusions.
- Pseudoaneurysms and acute hemorrhages.
Subcapsular hematoma?
Lenticular fluid collections that conform to the shape of the outer contour of the liver but which frequently flatten the adjacent liver parenchyma.
Most subcapsular hematomas occur?
ANTEROLATERALLY over the RIGHT hepatic lobe.
What is the MC finding in hepatic trauma?
Laceration.
Hepatic laceration?
Irregularly marginated, low attenuation, linear or branching defects, usually at the periphery.
“Fracture” is a term …?
That has been used to describe a laceration that avulses a section of the liver.
Intrahepatic hematomas?
Focal, high attenuation lesions first caused by blood.
Intrahepatic hematomas may progress to …?
Low attenuation, masslike lesions filled with serous fluid.
Hepatic trauma - Wedge-shaped defects?
Devascularized sections of liver parenchyma that do NOT contrast-enhance.
Hepatic injury - Contusions?
A term used to describe an area of minimal parenchymal hemorrhage.
–> LOWER attenuation than the surrounding liver and have indistinct margins.
Hepatic injury - Pseudoaneurysms and acute hemorrhage?
Irregular collections of HIGH attenuation, extravasated contrast that often require angiography with embolization or surgery.
Spleen trauma is usually caused by?
- Deceleration injuries in unrestrained occupants of motor vehicle collisions.
- A fall from a height.
- Pedestrian being struck by a motor vehicle.
Most splenic trauma is treated?
CONSERVATIVELY.
What is the study of choice in evaluating splenic trauma?
CT.
Splenic trauma - Contusion?
Alterations in the normal homogeneous appearance of the spleen, including mottled areas of LOW attenuation.
Splenic trauma - Subcapsular hematoma?
LOW attenuation, crescent-shaped collection of fluid in the subcapsular space which frequently compresses the normal splenic parenchyma.
Splenic trauma - Laceration?
Irregular, low-attenuation defect that typically transects the spleen.
Splenic trauma - Intraparenchymal hematoma?
Lacerations filled with blood –> Intrasplenic areas of low attenuation which may have a mass effect and enlarge the spleen.
Splenic trauma - Intraperitoneal fluid or blood?
Hemoperitoneum occurs with ALMOST ALL splenic injuries, including small amounts of blood in the pelvis –> Its presence does NOT necessarily indicate active hemorrhage.
MCC of blunt abdominal trauma to the kidneys?
Motor vehicle accidents.
Almost all patients with renal trauma have …?
Hematuria.
Study of first choice in renal trauma?
Enhanced CT.
CT findings in renal trauma (6)?
- Contusion.
- Subcapsular hematoma.
- Perinephric hematoma.
- Laceration.
- Vascular injuries.
- Injuries to the collecting system.
Renal trauma - Contusion?
Ill-defined, patchy, LOW attenuation areas in the contrast enhanced kidney.
Renal trauma - Subcapsular hematoma:
Crescentic or elliptical densities that compress the denser underlying renal parenchyma.
Renal trauma - Perinephric hematoma:
Ill-defined fluid collection surrounding the kidney confined by Gerota’s fascia.
Renal trauma - Laceration:
LOW attenuation linear or branching defects in the renal parenchyma.
Renal trauma - More severe lacerations may …?
Extend through the renal hilum into the collecting system, renal artery, or vein.
–> “Fracture” is a term that may be used when the laceration connects the hilum with the cortex.
Renal trauma - Vascular injuries:
If the injury is ARTERIAL –> There may be no flow to the kidney and hence, NO CONTRAST ENHANCEMENT.
Vascular injuries may also produce …?
Wedge-shaped defects in the kidney.
Renal trauma - Injuries to the collecting system:
Extraluminal contrast arising from the renal pelvis or ureter.
Shock bowel usually occurs with …?
Blunt abdominal trauma in which there is severe hypovolemia and profound hypotension, with complete reversibility of these findings following resuscitation.
Recognizing shock bowel on CT?
- Diffuse thickening of the small bowel wall with increased enhancement.
- Fluid-filled + dilated loops of bowel.
- Other findings include –> Small IVC (
About …% of bladder ruptures occur with pelvic fractures, and about …% of patients with pelvic fractures have an associated rupture of the bladder.
70%. 10%.
Bladder ruptures are best demonstrated by a …?
CT cystogram.
What happens in a CT cystogram?
Contrast is infused under gravity through a Foley catheter into the bladder, but they can also be well demonstrated by antegrade filling of the bladder from renal excretion of IV contrast.
2 types of bladder rupture?
- Extraperitoneal (80%).
2. Intraperitoneal.
Extraperitoneal bladder rupture is usually the result of?
A pelvic fracture with direct puncture of the bladder.
In extraperitoneal bladder rupture, the extraluminal contrast …?
Remains around the bladder, especially in the retropubic space.
Intraperitoneal bladder rupture is usually the result of a?
Forceful blow to the pelvis with a distended bladder, especially in children!
Intraperitoneal bladder rupture usually occurs at the …?
DOME of the bladder, adjacent to the peritoneal cavity.
Urethral injuries are associated with?
Significant pelvic trauma in males, most often blunt trauma.
Urethral injuries should be investigated when …?
There are straddle fractures of the pelvis OR penetrating injuries in the region of the urethra.
Suggestive clinical findings of urethral damage?
- Hematuria.
- Blood at the urethral meatus.
- Inability to void.
Urethral damage - Imaging?
Is done most often using retrograde urethrography (RUG).
What happens in retrograde urethrography?
Contrast is instilled retrograde at the urethral meatus with retrograde filling of the urethra.
This is done before insertion of a Foley catheter into the bladder.
MC urethral injury?
Is a rupture of the POSTERIOR urethra through the urogenital diaphragm into the proximal bulbous urethra.
