Which abdominal organ is most commonly injured due to blunt abdominal trauma?
The spleen is the most commonly injured organ in blunt abdominal trauma, accounting for up to 50% of visceral injuries, and CT is highly accurate in diagnosing splenic injury. Currently, the most widely used CT grading system for splenic injury is based on the American Association for the Surgery of Trauma (AAST) scale, although a more recent CT-based grading system has been shown to provide improved accuracy to predict the need for angiography or surgery. The spectrum of splenic injuries includes hematoma, laceration, infarction, active hemorrhage, and vascular injuries including pseudoaneurysm and arteriovenous fistula (AVF).
Intraparenchymal hematomas appear as round, ovoid, or irregular foci of nonenhancing high attenuation (30 to 70 HU) hemorrhagic fluid within the spleen; subcapsular hematomas are crescentic and peripheral in location and exert mass effect upon the splenic contour; and perisplenic hematomas surround the spleen in the peritoneal space without deforming the splenic contour. On MRI, subacute hemorrhage has high T1-weighted signal intensity.
Splenic lacerations appear as irregular, linear, branching, or stellate nonenhancing low attenuation parenchymal defects in the spleen, often with adjacent areas of high attenuation hemorrhage . When active hemorrhage is present, one sees focal areas of increased attenuation on contrast-enhanced images similar to that of enhancing vessels which do not conform to known vascular structures and which persist or increase in size on more delayed phase acquisitions. Splenic pseudoaneurysms and AVF also appear as well-circumscribed foci of contrast enhancement with attenuation similar to adjacent contrast-enhanced arteries but decrease in attenuation on more delayed phase acquisitions. Presence of active hemorrhage or of vascular injuries on CT are generally predictive of the need for splenic angiography and transcatheter embolization or splenic surgery.
