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The spleen, an important component of the reticuloendothelial system in normal adults, is a highly vascular solid organ that arises as a mass of differentiated mesenchymal tissue during early embryonic development. The normal adult spleen weighs between 75 and 100 g and receives an average blood flow of 300 mL/min. It functions as the primary filter of the reticuloendothelial system by sequestering and removing antigens, bacteria, and senescent or damaged cellular elements from the circulation. In addition, the spleen has an important role in humoral immunity because it produces immunoglobulin M and opsonins for the complement activation system.
Although the spleen resides under the confines of the left lower rib cage, it is frequently subject to both blunt and penetrating trauma. Isolated splenic injury after blunt trauma is common in children, whereas the adult trauma population will often sustain associated injuries to the thorax, kidneys, extremities, and head. The mechanism of injury in blunt trauma stems from abrupt deceleration resulting in vascular torsion of the splenic hilum, shearing of the short gastric vessels within the gastrosplenic ligament, or capsular tearing at sites of ligamentous fixation. Clinical features that suggest splenic trauma include left upper quadrant or flank ecchymosis and abrasions, as well as left shoulder pain caused by irritation of the left hemidiaphragm by subphrenic blood (Kehr sign). In instances of penetrating trauma, a wound track traversing the left upper quadrant raises the suspicion for splenic injury. Regardless of mechanism, all trauma patients should receive the primary survey, followed by the appropriate secondary evaluation and ancillary studies.
Currently, the accepted standard of care for most splenic trauma is expectant management with close observation. Operative intervention is reserved for the hemodynamically labile patient who shows signs of active hemorrhage and who does not respond appropriately to fluid resuscitation. Although these clinical scenarios seem straightforward, it is often the condition of the patient who falls in between the two ends of the spectrum that can be the most challenging to manage. In the setting of advanced imaging techniques and interventional radiology, the trauma surgeon has more diagnostic information and more treatment options for the patient with splenic trauma.
Patients who present with evidence of ongoing intraabdominal hemorrhage should undergo immediate operative exploration. For those who present with normal hemodynamics, a thorough diagnostic evaluation should be completed. Following the primary survey, a focused abdominal examination should be performed, looking for signs of significant intraabdominal injuries. Abdominal wall ecchymosis, abrasions, flank pain, and distention should raise suspicion for an injury and prompt further diagnostic work-up. The patient who presents with left-sided rib fractures should also be evaluated for a concomitant splenic laceration.
A laboratory panel should be sent to obtain an index hemoglobin and hematocrit, platelet count, and coagulation profile. While in the emergency department, the focused abdominal sonography for trauma (FAST) exam offers a rapid and noninvasive approach to detecting intraperitoneal blood. The sensitivity of FAST has been reported between 43% and 93%, whereas its specificity ranges in various reports between 90% and 98%. The primary limitations of FAST are the heavy operator dependence of the ultrasonographic exam, as well as the technical limitations caused by the patient's body habitus or intestinal gas. Branney et al. demonstrated the technical shortcomings of the technique by infusing volumes of diagnostic peritoneal lavage fluid into the peritoneal cavity and found that only 10% of participants performing FAST could detect fluid volumes of less than 400 mL. In spite of these obstacles, the FAST exam is helpful in the preliminary evaluation of the patient, especially when the patient cannot undergo further imaging because of hemodynamic instability. Given the ranges in sensitivity, it is important to remember a negative FAST without a computed tomography (CT) may result in missed intraabdominal injuries. In addition, in hemodynamically labile patients, the decision of exploratory laparotomy should not be distracted by a negative FAST.
Unlike ultrasonography, CT has dramatically changed the way we characterize splenic injuries. The CT scan is the diagnostic modality of choice for the hemodynamically stable patient in whom a splenic injury is suspected. The sensitivity and specificity of CT imaging approaches 100% and 98%, respectively. Current-generation multislice scanners provide a detailed survey of the splenic architecture and allow the clinician to differentiate simple subcapsular hematomas from more severe parenchymal and vascular injuries. Although exposing patients to increased radiation, the arterial phase of CT image acquisition—in addition to traditionally obtained portal venous and delayed phase images—should be considered to optimize the detection of traumatic splenic injuries.
Several grading systems have been used for classifying splenic injuries, and these have important implications in both the operative and nonoperative management decisions. The Organ Injury Scaling Committee of the American Association for the Surgery of Trauma (OISC-AAST) devised an anatomic grading system that defines the severity of splenic injuries. The system incorporates both CT scan findings and intraoperative assessment of the spleen and consists of five grades ( Table 139.1 ). This grading scale provides universal definitions that all clinicians can understand, and it becomes particularly useful when a patient requires transfer to a tertiary trauma center from an acute care hospital as the severity of injury is readily appreciated. Although the trauma community recognizes that the primary predictor of operative intervention is hemodynamic instability, the organ injury severity scale can also serve as a predictor of further therapeutic intervention. Haan et al. reported a splenic salvage rate of 94% over a 5-year period; however, they found that the salvage rate decreased with increased splenic injury grade.
Grade | Injury Description |
---|---|
I |
|
II |
|
III |
|
IV | Laceration involving segmental or hilar vessels producing major devascularization (>25% of spleen) |
V |
|
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