Pediatric Abdominal Trauma Imaging

Carlos J. Sivit, MD

Disclosures

Appl Radiol. 2013;42(5):8-13. 

In This Article

Solid Viscus Injury

The liver is either the most commonly injured or second-most commonly injured solid viscera. Hepatic injury is believed responsible for the most fatalities in which abdominal trauma is the primary cause of death. Most hepatic injury occurs in the posterior segment of the right lobe.[1] The effects of blunt force are maximized in this location because the posterior right lobe is fixated by the coronary ligaments, which limit its movement while the rest of the liver is free to move. Hepatic lacerations may be simple or stellate (Figure 1). Stellate or complex lacerations have a branching pattern. They may be associated with parenchymal or subcapsular hematoma. Hepatic injury is associated with hemoperitoneum in approximately two-thirds of cases.[2–3] Hemoperitoneum associated with hepatic injury principally relates to violation of the liver capsule at the site of injury. Hepatic injury may not be associated with hemoperitoneum if the injury does not extend to the surface of the liver, if the hepatic capsule is not disrupted, or if there is extension to the liver surface in the bare area of the liver, which is devoid of peritoneal reflection.[4] Injury extending to the bare area may lead to associated retroperitoneal hemorrhage.

Figure 1.

Hepatic laceration. Contrast-enhanced CT scan through the liver demonstrates a complex hepatic laceration.

The primary grading scale used to quantify hepatic injury was developed by the American Association for the Surgery of Trauma (AAST).[5] Attempts to develop CT classification systems have had limited success. The AAST grading scale emphasizes the anatomic extent of the injury, including capsular integrity, extent of subcapsular collection, extent of parenchymal disruption, and state of the vascular pedicle. This grading scale is universally utilized in children and adults. However, in children this scale is not predictive of need for operative management because most hepatic injuries can be successfully managed nonoperatively regardless of severity. In various reports between 1% and 3% of children with hepatic injury required surgical hemostasis.[6–7] The primary utility of the AAST grading scale in the pediatric age group is in nonsurgical patient management decisions, including duration and intensity of hospitalization and activity restriction.

Splenic injury is also common after blunt trauma. Splenic lacerations vary in appearance, ranging from linear to branching patterns (Figure 2). Because the spleen is much smaller than the liver, complex injury typically results in shattering or fragmentation of the spleen (Figure 3). Associated parenchymal or subcapsular hematoma may be present as seen with hepatic injury. Associated intraperitoneal hemorrhage is not always present, relating to whether a laceration extends to the spleen surface and whether the capsule remains intact. Absence of hemoperitoneum is observed in approximately 25% of splenic injuries.[2–3]

Figure 2.

Splenic laceration. Contrast-enhanced CT scan through the upper abdomen demonstrates a splenic laceration.

Figure 3.

Shattered spleen. Contrast-enhanced CT scan through the upper abdomen demonstrates a shattered spleen.

The AAST grading scale is also the primary grading scale for splenic injury. As is true for hepatic injury, this scale is not a measure of required surgical treatment, as nonoperative management is successful in most children with splenic injury. The primary utility of the AAST grading scale in pediatric patients is in nonsurgical patient management decisions.

The kidney is the third-most frequently injured abdominal viscera in children. The most common renal injury is the parenchymal contusion, manifested on CT by a focal or diffuse region of delayed-contrast enhancement. Renal lacerations appear as linear, low-attenuation areas in the parenchyma. Renal injury may be complicated by subcapsular or perinephric hematoma. Deep lacerations may involve the renal collecting system. Renal collecting system injury results in urinary extravasation of IV contrast medium (Figure 4).[8] Delayed imaging through the kidneys is useful in detecting extravasation. Urine leakage typically remains encapsulated in the perirenal space and may lead to urinoma. Conservative treatment is successful in the management of most high-grade renal injury.[9]

Figure 4.

Renal collecting system injury. Delayed contrast-enhanced CT scan through the mid-abdomen shows a left renal laceration with extravasation of intravenous contrast into the perirenal space.

Renal infarction occurs after a main or segmental renal arterial branch is lacerated. Injury to a segmental renal artery produces a segmental renal infarct. The appearance at CT is that of a peripheral, wedged-shaped area of nonenhancing parenchyma.[10–11] These are typically managed nonoperatively and result in a focal area of renal scarring. Injury to the main renal artery results in devascularization of the entire kidney. This is the most severe form of renal injury. Early recognition is essential, as prompt vascular repair is crucial to prevent permanent loss of renal function.[12]

Pancreatic injury is relatively uncommon in children. Approximately 2/3 of injuries occur in the pancreatic body. Direct signs of injury may be difficult to identify, owing to the small size of the gland, the paucity of surrounding fat, and the minimal separation of fracture fragments. Transection results in complete separation of pancreatic fragments (Figure 5). Unless the two edges of a fracture are separated by low-attenuation fluid or hematoma, the diagnosis may be difficult to recognize at CT. The best indicator of pancreatic injury at CT is unexplained peripancreatic fluid (fluid in the anterior pararenal space or lesser sac) (Figure 6).[13–14] This finding may be seen more often than the actual laceration. When fluid collects in the anterior pararenal space it may also dissect between the pancreas and splenic vein.[14–15] Additional CT signs of pancreatic injury are typically due to associated pancreatitis. These include focal or diffuse gland enlargement, stranding of peripancreatic and/or mesenteric fat, thickening of the anterior renal fascia, and free peritoneal fluid.

Figure 5.

Pancreatic transection. Contrast-enhanced CT scan through the upper abdomen demonstrates a pancreatic transection at the junction of the head and body.

Figure 6.

Pancreatic injury with associated peripancreatic fluid. Contrast-enhanced CT scan through the upper abdomen demonstrates a laceration through the body of the pancreas. Note the fluid in the anterior pararenal space anterior to the pancreas.

Identification of pancreatic duct disruption may impact patient management although there are currently divergent opinions regarding the management of ductal injury. The nonoperative management of most pancreatic injury has been proven successful by some, even when there is involvement of the pancreatic duct.[16–17] Others feel that a distal pancreatectomy for transection to the left of the spine is the treatment of choice as it is definitive with decreased complications.[18–19] Injury to the pancreatic duct can be predicted at CT by evaluating the depth of laceration. More precise assessment of the pancreatic duct is obtained with MRCP.

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