Management of Trauma to the Liver and Spleen

Imaging Work-Up

Initial trauma care involves the resuscitation of the trauma patient with simultaneous imaging to assess whether there is ongoing bleeding and whether bleeding is arterial or venous in origin, and to evaluate the extent and grade of the various injuries to the visceral organs. Initial imaging assessment is performed using a combination of conventional imaging and focused abdominal sonography for trauma (FAST) or using immediate whole-body computed tomography (WBCT). Although there is no evidence that immediate WBCT improves outcomes in terms of survival compared with assessment with FAST and conventional imaging followed by on-demand computed tomography (CT) scanning when necessary, it has been shown to significantly decrease emergency room time. In addition to this, CT has many advantages over FAST. CT is better for the detection and grading of solid-organ and mesenteric injuries as well as the detection of retroperitoneal hematoma. CT can also reliably detect active bleeding, including the source of bleeding, differentiate arterial from venous bleeding, and provide a vascular road map, which may serve as a guide for angiography and embolization. Single-phase contrast-enhanced CT with a so-called split bolus technique and arms raised over the head combines optimal imaging with acceptable radiation exposure. However, a multiphase protocol incorporating arterial-phase imaging provides better anatomic detail of the arterial vascular tree, which may be useful for guiding angiography, albeit at the expense of higher radiation exposure. FAST and conventional imaging can be performed simultaneously with resuscitation in hemodynamically unstable patients, which can be an advantage of these techniques. However, with the advent of CT scanners placed in the trauma unit, performing CT in hemodynamically unstable patients who are being resuscitated is now also becoming possible. When there is uncorrectable hemodynamic instability in a patient with abdominal injury, FAST should be done to search for hemoperitoneum. If hemoperitoneum is seen on FAST, it should lead to immediate laparotomy. In this scenario, there is no place for additional CT scanning or angiography and embolization. However, in hemodynamically unstable patients, who present with a combination of a pelvic fracture and a suspicion of abdominal injury, FAST can also be very important. This is because the absence of hemoperitoneum is strongly suggestive of retroperitoneal pelvic bleeding as the cause of the hemodynamic instability and this would not require laparotomy but immediate angiography and embolization or pelvic packing. When a patient who has hemoperitoneum on FAST is stable enough to undergo CT scanning, this should always be the next step because CT may guide the treatment choice and the order of the steps of treatment (e.g., laparotomy, embolization alone, or embolization followed by laparotomy).

Imaging Findings

Several injury grading systems have been proposed to describe CT findings of trauma to the liver and spleen, of which the American Association for the Surgery of Trauma (AAST) injury grading system is the best known. High-grade organ injury (grade 3 or more) has been used as an indication for angiography and embolization. However, the correlation between injury grade and the presence of bleeding is inconsistent. Moreover, as the AAST grading system does not incorporate active bleeding, it has limited value for deciding on the indication for angiography and embolization. As a result, it is not routinely used in the acute trauma setting to select patients for angiography and embolization.

Systems incorporating active bleeding have been shown to be more useful for this purpose. The most important CT feature is the “contrast blush,” which has been shown to be a reliable predictor of active bleeding found on angiography. A contrast blush represents active extravasation of contrast medium from a vessel and may be confined to the organ but may also be seen extending into the peritoneal space.

Vascular lesions other than active bleeding should be actively searched for on CT scans because these may also indicate the need for angiography. Such findings are known as “cut-off” vessels, which represent dissected or completely transected vessels without active bleeding. These are prone to rebleed when the clot dissolves or spasm disappears when normal blood pressure is restored during resuscitation. Other vascular lesions are false aneurysms, which may lead to ongoing hemorrhage when they rupture and arteriovenous fistulas, which are also associated with ongoing hemorrhage, particularly in the spleen.

Expanding hematoma seen on sequential CT scans may indicate ongoing bleeding even in the absence of a contrast blush and associated solid-organ injury. The presence of a sentinel clot, which is seen as a relatively hyperdense clot as compared with the surrounding hemoperitoneum, may indicate the source of the hemorrhage. This is particularly helpful when there is doubt about the origin of the bleeding, e.g., when there is no parenchymatous injury visible to either the liver or the spleen or when there is parenchymatous injury visible to both the liver and the spleen. Isolated hemoperitoneum without any signs of associated solid-organ injury may sometimes also be found, but it is unclear what its value is because the source of the bleeding cannot be localized. There should be a low threshold for considering mesenteric injury in such cases and these may require laparotomy, because missing bowel injury may lead to peritonitis and this should be prevented if at all possible.

Indications for Angiography and Embolization

Indications for angiography and embolization are the result of a combination of clinical and imaging findings. The strongest indication is the combination of clinical signs of ongoing bleeding and imaging showing a contrast blush. Clear clinical signs of ongoing bleeding in the absence of a contrast blush on imaging can be an indication to proceed to angiography in selected cases because bleeding may be intermittent and missed on cross-sectional imaging. Similarly, an expanding hematoma without a contrast blush seen on sequential CT scans may indicate intermittent ongoing bleeding, which requires treatment. The combination of a contrast blush on imaging and the absence of clinical signs of bleeding is a more controversial indication for angiography and embolization, although there should be a low threshold to proceed to angiography in such cases. Indeed, not all contrast blushes will require embolization, but it is difficult to predict in which patients bleeding will cease spontaneously and which patients will continue to bleed. Because angiography is minimally invasive and has a low complication rate, a pragmatic approach is to have a low threshold for performing angiography and embolization in most such cases.

Cut-off vessels, false aneurysms, and arteriovenous (AV) fistulas are an indication for treatment even though most patients with such imaging findings will not have clinical signs of bleeding because these may lead to delayed rupture and bleeding as discussed previously.

Contraindications for Angiography and Embolization

The only real contraindication to angiography and embolization is uncorrectable severe hemodynamic instability, which should lead to immediate laparotomy. However, the definition of hemodynamic instability is subjective, and deciding which patients require immediate laparotomy and which patients may safely undergo embolization depends on local infrastructure and logistics.