Pancreatic Trauma

Pancreatic injury is a relative enigma, even in modern medical practice with technology and advanced diagnostic methods. Although initially hard to diagnose, most minor pancreatic injuries are relatively easy to treat. However, a delayed diagnosis of pancreatic injury, mild or severe, is easy to diagnose but becomes a major therapeutic challenge to the medical team and a potentially disastrous situation for the patient.

The pancreas, sitting in a relatively protected position high in the retroperitoneum, is infrequently injured in typical blunt injuries (eg, from motor vehicle crashes) compared with its splenic and hepatic counterparts. Accordingly, many blunt pancreatic injuries are not immediately recognized and consequently end up causing higher morbidity and mortality rates than observed in injuries to other intraperitoneal organs. ^{[1, 2]}

Conversely, penetrating abdominal trauma—by its very nature usually mandating emergency exploration—more frequently includes pancreatic injury. But even physical visualization and examination of the pancreas in the operating room may miss an isolated ductal injury to the pancreas without adjunctive tests.

This article summarizes the findings commonly associated with pancreatic injury, available diagnostic modalities and their sensitivities, and treatment issues and options.

Frequency

The overall rate of blunt pancreatic injury observed in level 1 trauma centers is rather low compared with other injuries. The pancreas is estimated to be the 10th most injured organ compared to other organs (eg, brain, spleen, liver). To consider a pancreatic injury, a trauma that occurred from a significant force is usually required. The incidence of diagnosed pancreatic injury is expected to be higher at a trauma center specializing in serious injury than at a community hospital. Of 100 patients with blunt trauma, fewer than 10 will have a documented pancreatic injury.

The incidence of pancreatic injury in patients with a penetrating trauma is much higher. Gunshot wounds (GSWs); shotgun injuries; and stabbings to the back, flank, and abdomen (defined as nipple level to inguinal ligament) frequently include pancreatic injury, occurring in approximately 20-30% of all patients with penetrating traumas. ^[3] This occurrence elicits another key point in pancreatic trauma: Because the blunt force required to injure the pancreas is so significant and penetrating trauma usually injures multiple organs, a pancreatic injury is rarely a solitary injury. When the pancreas is injured, with the possible exception of child abuse or the well-placed stab in the back, the physician or surgeon can be confident that other organs are also affected. Therefore, multiple organ injury is a red flag suggesting the possibility of a pancreatic injury.

Because of its anatomic position (see Relevant Anatomy), an isolated pancreatic injury may occur with penetrating trauma to the mid back in the form of stab wounds or impalement. In a blunt trauma–induced isolated pancreatic injury, fracture over the spinal column is usually observed in smaller children and is caused by direct abdominal blows from malpositioned seat belts or intentional child abuse. Fortunately, both of these situations are relatively rare.

Usually, penetrating trauma caused by firearms results in the highest frequency of pancreatic injury and is almost always associated with concurrent injury to other intra-abdominal organs. This injury can result in a relatively simple isolated puncture of the body or tail of the pancreas (a highly complex and difficult injury) or an injury to the pancreatic head with involvement of the biliary and pancreatic ductal systems. In addition, the proximity of the larger vessels (eg, portal vein), the abdominal aorta, and the inferior vena cava (IVC) to the pancreatic head increases the risk of exsanguinating hemorrhage accompanying pancreatic penetrating injury. Exsanguinating hemorrhage due to concomitant vascular injury accounts for the greatest number of deaths in patients with pancreatic injury.

Unlike the spleen, few data suggest that preexisting primary or secondary diseases of the pancreas result in a higher risk of injury or a higher mortality rate when the pancreas is injured. Clearly, preexisting severe pancreatitis or diabetes mellitus negatively affects the overall mortality and morbidity rates in patients with pancreatic trauma, but few published data support this commonly held clinical view.

However, the postinjury development of pancreatitis or diabetes mellitus is a different issue. The development of either of these conditions after injury is associated with a significant increase in morbidity and overall mortality rates in patients who experience trauma.

The type of injury (ie, blunt vs penetrating) and information about the injuring agent (eg, GSW, knife) help focus the clinician on the possibility of pancreatic injury.

During the physical examination, seat belt marks, flank ecchymoses, or penetrating injuries should alert the physician to the potential for pancreatic injury. Pancreatic injury can be frighteningly symptom free early in the postinjury time frame and even silent in many cases. Rarely, a contained fracture of the spleen with retroperitoneal hematoma or leak manifests as dull epigastric pain or back pain, but the more common scenario is for patients to exhibit severe peritoneal irritation and a positive abdominal examination finding, usually caused by injury to other organs. Symptoms of injury to other structures commonly mask or supersede that of pancreatic injury, both early and late in the hospital course. Therefore, a high degree of clinical awareness is necessary to ensure that pancreatic injuries are not overlooked or missed, either early in the course of trauma or later in the ICU when the patient is not clinically improving as expected.

CT scan findings of pancreatic trauma are generally categorized as direct signs (eg, pancreatic laceration) that tend to be specific but lack sensitivity and indirect signs (eg, peripancreatic fluid) that tend to be sensitive but lack specificity. ^[4]

In patients experiencing blunt trauma, CT scans provide the best overall method for diagnosis and recognition of a pancreatic injury. Retroperitoneal hematoma, retroperitoneal fluid, free abdominal fluid, and pancreatic edema frequently accompany injuries to the pancreas.

In patients with penetrating trauma, visualization of perforation, hemorrhage or fluid leak (eg, bile, pancreatic fluid), or retroperitoneal hematoma around the pancreas suggests the need for further evaluation.

In cases in which the CT scan findings are indefinite or clinical suspicion of a pancreatic injury remains, further investigation with magnetic resonance cholangiopancreatography (MRCP) may be used. Although injury of the main pancreatic duct may be strongly suggested upon initial CT scanning, MRCP can demonstrate clear delineation of the duct and its integrity. ^[4]

Located in a relatively protected area of the abdominal cavity, the pancreas is high and posteriorly situated in a fixed retroperitoneal position. The rib cage provides a bony structural protection, in addition to the protection afforded by the thick dorsal muscle groups (paraspinous). Anteriorly, the mature adult rectus and abdominal muscles, combined with the energy-absorbing characteristics of the liver, colon, duodenum, stomach, and small bowel, provide physiologic padding that protects the pancreas from blunt injury. In severe blunt trauma, the anatomic position may result in injury (eg, fracture of the body over the spinal column and vertebral bodies posteriorly). However, the anatomic position of the pancreas neither protects nor increases the risk from penetrating injury.

The proximity of vascular structures to the head of the pancreas has a marked effect on the morbidity and mortality rates of patients who experience a pancreatic injury. The subhepatic IVC and the aorta sit just posterior to the pancreatic head to the patient's right side, and the superior mesenteric vein coalesces into the portal vein immediately behind the pancreas. Exsanguinating hemorrhage from concurrent injury to these vessels is a frequent cause of death in patients with a pancreatic injury.

The splenic artery (off the celiac trunk) and vein (draining into the portal vein) run superior and posterior to the body and tail of the pancreas and are relatively easier to expose and control compared to the IVC and portal vein. The vascular anatomy that causes such difficulty in repairing injuries to the head of the pancreas actually makes injuries to the body and tail easier to manage.

No absolute contraindications exist for pancreatic exploration or resection in patients who are experiencing trauma. The presence of hypothermia, dilutional coagulopathy, and other fatal or near-fatal injuries obviously influences the surgeon's decision to use damage-control techniques versus operative repair or resection. A trauma surgeon may explore and widely drain, perform a segmental resection, or even, very rarely, perform a trauma Whipple procedure (pancreatic duodenectomy) initially or in delayed fashion, depending on the presence of other injuries and the physiologic condition of the patient.