Pancreatic Trauma

Secondary signs of pancreatic injury are usually present (peripancreatic fat stranding and fluid, thickening of pararenal fascia, peripancreatic hematoma)

– Peripancreatic signs of traumatic pancreatitis often subtle; more evident in 24-48 hours

Pancreatic contusion: Ill-defined focal hypoattenuation at site of injury (not linear like laceration)

Pancreatic laceration: Discrete linear hypodense cleft through pancreas

Pancreatic fracture: Large laceration with clear separation of 2 ends of gland

CT insensitive for pancreatic duct injury (usually inferred by laceration extending through duct)

• MR: MRCP (± secretin) is a useful tool in determining presence of pancreatic ductal disruption

• ERCP: Best modality for pancreatic ductal injury

Transection of pancreatic duct: Abrupt duct termination or contrast extravasation

PATHOLOGY

• May result from either penetrating or blunt trauma

Blunt traumatic injury usually results from anterior/posterior compression force to abdomen

• Pancreatic injuries almost never isolated and usually associated with polytrauma

CLINICAL ISSUES

• Blunt pancreatic injuries often clinically occult and unrecognized on initial evaluation

• Clinical presentation often due to traumatic pancreatitis: Upper abdominal pain, abdominal distention

• Serum amylase/lipase levels: Elevated in 90% of patients, but may be normal immediately after trauma

• Treatment: Penetrating trauma generally requires immediate laparotomy

AAST grades I and II: Conservative management

AAST grades III, IV, and V: Typically require surgery (including possible pancreatic resection)

(Left) Axial CECT shows subtle laceration of the pancreas with fluid in the lesser sac as well as retropancreatic fluid .

(Right) Axial CECT in the same patient reveals fluid tracking posterior to the pancreas along the splenic vein from extravasated pancreatic juice. Secondary signs of injury, such as peripancreatic fluid, hematoma, or fat stranding, are almost always present as a clue to the diagnosis.

(Left) Axial CECT in a patient with pancreatic fracture shows a fracture plane through the neck of the pancreas. The pancreatic duct was disrupted, and the body and tail of the pancreas were resected at surgery.

(Right) Axial CECT 48 hours after trauma shows a pseudocyst in the lesser sac in this pancreatic transection .The fluid collection developed as a result of leakage of fluid from the site of the transected pancreatic duct.

TERMINOLOGY

Synonyms

• Traumatic pancreatic injury

Definitions

• Inflammatory disease of pancreas secondary to trauma

IMAGING

General Features

• Best diagnostic clue

Enlarged, heterogeneous pancreas with peripancreatic fluid or hematoma in patient with history of trauma

• Location

Most commonly involves pancreatic body > head > tail

• Morphology

Spectrum of injury: Acute pancreatitis, contusions, deep lacerations, fractures with ductal disruption

Radiographic Findings

• ERCP

Normal in cases of pancreatic contusion

Best modality to identify pancreatic duct (PD) injury

– Transection of PD: Abrupt duct termination or contrast extravasation

– Communication of pseudocyst with PD

May cause pancreatitis

CT Findings

• Secondary signs of pancreatic injury or post-traumatic pancreatitis usually present even in absence of discrete contusion/laceration

Peripancreatic fat stranding and fluid with loss of normal peripancreatic fat planes almost always present

– Fluid separating pancreas from splenic vein is sensitive (60-90%) for pancreatic injury

– Fluid or hematoma is often seen in lesser sac, left anterior pararenal space, transverse mesocolon, adjacent to spleen, and mesenteric root

Thickening of anterior pararenal fascia

Peripancreatic or intrapancreatic hematoma: Intrapancreatic hematoma is more specific for pancreatic injury

Peripancreatic signs of traumatic pancreatitis are often subtle: May be more evident in 24-48 hours

• Pancreatic contusion: Ill-defined focal hypoattenuation at site of injury

Appearance ranges from subtle contour deformity of pancreas to rounded mass-like enlargement of pancreas several cm in diameter

Often associated with focal or diffuse pancreatic enlargement

• Pancreatic laceration: Discrete linear cleft of hypoattenuation running through pancreas (usually perpendicular to long-axis of gland)

Much more likely to be associated with PD injuries than contusion

Often associated with distortion or irregularity of contour of pancreas and hypoenhancement of gland upstream from laceration

Lacerations may produce subtle parenchymal density changes and may be undetectable on CT in some cases

– 20-40% of pancreatic injuries not visible on initial imaging

– May only be faintly visible on initial imaging, and become more conspicuous on follow-up imaging

CT is not sensitive for detection of PD injury (∼ 40%): Inferred by presence of laceration extending through duct (> 50% of pancreatic thickness)

• Pancreatic fracture: Linear low attenuation running through pancreatic parenchyma with clear separation of 2 ends of gland

Most often through pancreatic neck

• Pancreatitis secondary to ERCP (± papillotomy, etc.) usually more severe in/around pancreatic head

MR Findings

• Variably decreased signal on T1WI at sites of contusion or laceration ± high T1 signal related to hematoma

• High signal on T2WI at sites of contusion or laceration

• Heterogeneous enhancement on T1WI C+ images with areas of nonenhancement related to fluid collections, pseudocysts, necrosis, laceration, or severe contusion

• MRCP useful tool to determine PD disruption

Secretin stimulation may improve diagnostic sensitivity

Ductal injury suggested by discontinuity in PD, along with direct communication to adjacent pseudocyst or fluid collection

Ultrasonographic Findings

• Not sensitive for pancreatic injury or complications

• Findings similar to pancreatitis (enlarged, hypoechoic gland)

Imaging Recommendations

• Best imaging tool

CECT for initial evaluation after trauma

Emergency ERCP: Investigate pancreatic injuries when CT positive and status of PD uncertain

• Protocol advice

• Repeat CT at 24-48 hours may identify pancreatic injuries not appreciated on original examination

DIFFERENTIAL DIAGNOSIS

Shock Pancreas

• Part of hypoperfusion complex seen in severe traumatic injuries or in setting of severe hypotension

• Abnormally intense enhancement of pancreas, bowel wall, and kidneys, with decreased caliber of aorta and inferior vena cava, and diffuse dilatation of intestine with fluid