Endovascular Management of Pelvic Trauma

Abstract

Major pelvic fractures result from high-energy trauma including traffic accidents and falls, which usually leads to multiple injuries complicating the patient's management. Management of these patients requires a coordinated multidisciplinary approach. Transcatheter embolization is a minimally invasive and effective technique to control massive hemorrhage and can be performed using a variety of embolic agents. It has become an accepted first-line management option for retroperitoneal bleeds in many centers. In this article, the indications for endovascular management of hemorrhage from pelvic trauma, the various embolization techniques, and potential complications will be discussed.

Major pelvic fractures result from high-energy trauma including traffic accidents and falls, which usually leads to multiple injuries complicating the patient's management. Pelvic fractures are present in 4 to 9% of patients with blunt trauma and are associated with significant morbidity and mortality. ^{1 2} Management of these patients require a coordinated approach between trauma surgeons, orthopedic surgeons and interventional radiologists. Endovascular interventions can be lifesaving in patients with hemorrhage from pelvic fractures with hemodynamic instability. Such interventions have become an accepted first-line management option for pelvic bleeds in many centers. In this article, the authors will discuss the indications for endovascular management of hemorrhage from pelvic trauma, the various embolization techniques, and potential complications.

Diagnosis of Pelvic Hemorrhage

The diagnosis of pelvic trauma–related hemorrhage can be made clinically, by imaging, or during operative repair of a pelvic fracture. ³ The presence of unstable pelvic fracture is a predictor of arterial extravasation. ⁴ Imaging diagnosis is mostly obtained by contrast-enhanced CT scan, especially in stable patients or patients who are responsive to resuscitation. Contrast-enhanced CT is fast, readily available in most centers, and provides detailed information about the type and location of the hemorrhage; the presence of vascular injuries such as pseudoaneurysm, arteriovenous fistula, or complete vascular transection; and the presence of vascular anatomic variants. The development of widely available fast scanners resulted in a change in the clinical practice, and currently CT scans are performed even on hemodynamically unstable patients. ⁵

In the event the patient was hemodynamically unstable or difficult to transport, focused assessment by sonography for trauma (FAST) and diagnostic peritoneal lavage (DPL) can be used to diagnose intraperitoneal bleed in patients not responding to fluid resuscitation, which necessitates operative intervention. If intraperitoneal and intrathoracic bleeds are excluded, and the patient is still hemodynamically unstable, a retroperitoneal bleed should be suspected. ³

Management of Pelvic Trauma

There are two approaches for the management of patients with pelvic trauma–related hemorrhage. The first approach is transcatheter pelvic angiography and embolization as indicated. The second approach is operative external fixation and preperitoneal pelvic packing. The choice of the approach depends on whether the source of hemorrhage is arterial or venous, the availability of resources particularly subspecialized physicians, operative experience, the patient's clinical condition, and the presence of associated injuries such as intraperitoneal hemorrhage. Despite that, it should be emphasized that most of the patients who undergo preperitoneal pelvic packing end up requiring transcatheter embolization.

Survival outcomes are documented to be better in patients who undergo angiography and transcatheter embolization first followed by operative intervention even in the presence of hemoperitoneum. ⁶ The timing of angiography and embolization is very critical in these patients. Delayed pelvic angiography and transcatheter embolization in these patients may be associated with poor outcomes and increased in-hospital mortality. ⁷ Tesoriero et al reported a median time to angiography of 286 minutes in a cohort of 344 patients with pelvic fractures who underwent pelvic angiography. Most of the delays were due to time spent awaiting mobilization of resources needed to perform angiography which allows ongoing hemorrhage. Nearly 80% of the deaths in their study could be attributed to early uncontrolled hemorrhage. They suggested that early surgical intervention like preperitoneal packing and resuscitative endovascular balloon occlusion of the aorta (REBOA) and the use of hybrid operative suites may improve the outcome. ⁸ A recent study found that preperitoneal pelvic packing alone is not effective for arterial hemorrhage control. ⁴ The decision to proceed with preperitoneal pelvic packing or angiography and embolization should be tailored to individual patient and based on availability of resources and experience. For these reasons, the current practice of most level 1 trauma institutions is to have interventional radiology services available to perform angiography and possible embolization within 30 minutes of the activation of a trauma code requiring endovascular intervention. Having a trauma interventional radiology hybrid operating room angiography suite is also gaining acceptance in most level 1 trauma hospitals, as it provides not only a shorter time to hemorrhage control but also a cohesive collaborative management of trauma patients by members of the trauma and interventional radiology teams.

Indications and Contraindications for Pelvic Angiography

Clinical indications for pelvic angiography in a patient with pelvic traumatic fracture include (1) persistent hypotension after 2 L of fluid challenge with exclusion of intraperitoneal hemorrhage, (2) transfusion requirement exceeding four units of blood within 24 hours or six units within 48 hours, (3) a pelvic hematoma greater than 600 mL or active extravasation seen on CT, and (4) a large or expanding pelvic hematoma found on laparotomy. ^{3 9 10} Recent studies have suggested that angiography and transcatheter embolization should be guided by the hematoma volume, rather than by the presence or absence of contrast extravasation alone. ¹¹

Contraindications for pelvic angiography are relative and include rapidly expanding hematoma, and ruptured hematoma into the peritoneum or through a perineal wound. Intraoperative packing to provide temporary control and subsequent transfer to the angiographic suite for transcatheter embolization may be the best approach to stop bleeding from pelvic arteries that are difficult to control surgically. ^{12 13}

Angiographic Technique

The use of ultrasound guidance to obtain vascular access is very helpful, especially in patients with hypotension, collapsed vessels, weak pulses, or groin hematoma/edema. Using ultrasound guidance, percutaneous femoral access is obtained on the side with less involvement by the fracture or the hematoma. If the hematoma involves the groin or there is severe edema secondary to aggressive fluid resuscitation, with difficulty obtaining femoral access, radial access can be considered. Other possible access sites are the brachial or axillary arteries. The procedure can be performed with only moderate sedation, with continuous monitoring of vital signs. General anesthesia is not required, unless indicated by other clinical conditions. Anesthesia support is helpful in most patients with hemodynamic instability and allows the interventional radiologist to focus more on the endovascular technique. Bladder catheterization using a Foley catheter is helpful to avoid obscuring pelvic hemorrhage by contrast filled bladder. Both un-subtracted and subtracted images should be reviewed to eliminate bowel movement artifacts. Imaging at two to three frames per second is usually adequate. The imaging should continue into the venous phase to distinguish extravasation from early draining vein.

An aorto-bi-iliac angiography (pelvic angiography) is performed using a standard pigtail catheter in the anteroposterior projection, followed by selective internal iliac catheterization and angiography in the ipsilateral oblique projection using a 4- or 5-Fr diagnostic catheter. This projection helps separate the internal iliac artery branches. Both internal iliac arteries should be evaluated, as bleeding can be bilateral and from multiple sites. Review of available imaging studies to recognize the fracture type and location and other CT findings can be helpful predict the injured vessels, and minimize unnecessary radiation exposure and contrast use. ¹

If angiographic signs of hemorrhage or vascular injury are noted, further superselective catheterization and angiographies of the injured or bleeding vessel are then performed, usually using a microcatheter. These angiographic signs include free contrast extravasation, pseudoaneurysm formation, vascular occlusion, vascular narrowing, transection or cutoff, intimal flaps, filling defects, or arteriovenous fistula. Contrast extravasation should persist into the venous phase ( Fig. 1 ).

Fig. 1.

A 16-year-old-male patient with history of motor vehicle accident and pelvic trauma. ( a ) CT of the pelvis revealed left obturator ring and pubic bone fracture with adjacent hematoma and a focus of contrast extravasation suggesting active bleeding (white arrow). ( b ) Selective left internal iliac angiography showing a tiny focus of contrast extravasation from a branch of the left internal pudendal artery (arrow). ( c ) Selective left internal pudendal angiography confirming the presence of contrast extravasation (arrow). ( d ) Superselective distal left internal pudendal angiography showing small pseudoaneurysm (white arrow) and free contrast extravasation (black arrow). ( e ) Left distal internal pudendal angiography following coil embolization (arrow) showing no flow in the embolized vessel.

Arteries may appear narrowed secondary to hypovolemic shock or vasopressors use. Absence of contrast extravasation may be related to transient vasospasm, inadequate blood flow due to hypotension or vasopressors, or temporary clotting, which can limit the angiographic evaluation. ¹⁴

In these cases, a selective hand injection of the suspected vessel can help overcome these issues ( Fig. 2 ). Occluded pelvic vessels, narrowed vessels, or vessels with filling defects suggesting a local thrombus should preferably be treated by embolization if they can be sacrificed. ³

Fig. 2.

A 51-year-old man with history of pelvic trauma from a tree falling on him. ( a ) CT of the pelvis showing active extravasation in the left anterior pelvis (arrow). ( b ) Selective left internal iliac angiography showing a truncated left internal pudendal artery (arrow). ( c ) Superselective distal left internal pudendal angiography showing disruption of the formed clot resulting in contrast extravasation indicating active bleeding. ( d ) Left distal internal pudendal angiography following coil embolization (arrow) showing no flow in the embolized vessel.

Evaluation of the lumbar, external iliac, and femoral arteries can be performed based on the CT findings ( Fig. 3 ). Unusual cases of bleeding from variant obturator artery originating from the inferior epigastric branch of the external iliac artery (corona mortis) or the external iliac artery itself have been reported. ^{15 16 17} It is advisable that both external iliac arteries should be evaluated in patients with pubic bone fractures/hemorrhage ( Fig. 4 ).

Fig. 3.

A 59-year-old woman with history of motor vehicle accident. ( a ) CT scan showing right pectineus muscle hematoma with contrast blush concerning for active bleeding (white arrow). ( b ) Right external iliac angiography showing a tiny focus of contrast extravasation from a branch of the right profunda femoris artery (arrow). ( c ) Superselective catheterization and angiography of the right medial circumflex femoral showing contrast extravasation from a small branch (arrow) corresponding to the contrast blush seen on CT image. ( d ) Right medial circumflex femoral angiography following coil embolization (arrow) showing occlusion of the targeted vessels with no residual contrast extravasation.

Fig. 4.

Young patient with motor vehicle accident undergoing pelvic angiography for the evaluation of pelvic hematoma. ( a ) Initial CT scan revealed bilateral obturator ring fractures, small left obturator hematoma, and tiny contrast blush suggesting active bleeding (white arrow). ( b ) Aorto-bi-iliac angiography showing irregularity in the right superior gluteal artery (arrowhead) without definite extravasation. Note that bilateral obturator arteries (black arrows) are arising from the inferior epigastric arteries (white arrows). ( c ) Following Gelfoam embolization of bilateral internal iliac arteries, a selective left external iliac angiography demonstrates an irregular left obturator artery (black arrow) arising from the inferior epigastric artery (white arrow), without definite extravasation. ( d ) Superselective left obturator angiography confirming vessel caliber irregularity without extravasation. ( e ) Superselective left inferior epigastric angiography following Gelfoam embolization of the left obturator artery showing patent left inferior epigastric artery and occluded left obturator artery (arrow).

Whether to perform a selective or nonselective embolization is still debatable, but depends largely on the patient's hemodynamic status, urgency to stop the bleeding, and operator preference and experience. If bleeding control is urgent but not emergent, we recommend a selective or superselective embolization of the focal bleeding site. This requires the use of microcatheter system which takes longer time to perform and is more technically demanding ( Fig. 5 ). Nonselective embolization of unilateral or bilateral internal iliac arteries or their anterior or posterior divisions is less time consuming and is preferred in patients with hemodynamic instability, ongoing hemorrhage, and the presence of multiple vascular injuries ( Fig. 6 ). The presence of extensive collateral circulation between the internal iliac artery branches minimizes the risk of infarction following transcatheter embolization of the internal iliac artery. If selective internal iliac angiographies were negative for arterial bleeding, theoretically performing transcatheter embolization can decrease venous bleeding by decreasing the arterial pressure head. A recent study showed that performing embolization in the presence of a negative angiogram did not change the need for transfusion. However, it may aid in hemorrhage control as evidenced by decreased amount of products transfused. ¹⁸

Fig. 5.

Young patient with gunshot wound and initial CT (not shown) revealing a large right pelvic hematoma and pseudoaneurysm. ( a and b ) Aorto-bi-iliac angiography showing occlusion of the right internal iliac artery with reconstitution of the branches of the posterior trunk through collaterals between the right lumbar and ilio-lumbar arteries (arrowhead). Arterial injury and pseudoaneurysm are seen in the proximal portion of the right superior gluteal artery and are seen more prominently in the late arterial phase (arrow). ( c ) Angiography of the common trunk of the fifth lumbar arteries demonstrates the collateral flow to the branches of the posterior trunk of the right internal iliac artery. The pseudoaneurysm of the proximal right superior gluteal artery is again seen (arrow). Note the bullet fragment (arrowhead). ( d and e ) Catheterization of the right superior gluteal artery through ilio-lumbar collaterals using a microcatheter (arrowheads) and deployment of coils in the pseudoaneurysm as well as the proximal and distal portions to the arterial injury (arrows) to prevent back door bleeding through collaterals. ( f ) Postembolization angiography showing occlusion of the pseudoaneurysm and the injured artery with collateral flow to the distal right superior gluteal artery through the right fifth lumbar artery (arrow).

Fig. 6.

A 23-year-old patient with history of motor vehicle accident resulting in pelvic fractures. The patient is status post internal fixation with persistent transfusion requirement. ( a ) CT scan showing left sidewall pelvic hematoma with small foci of extravasation (white arrow). ( b ) Aorto-bi-iliac angiography showing no definite extravasation or vascular abnormality. ( c ) Selective left internal iliac angiogram showing multiple small foci of extravasation (arrows). ( d ) Delayed images showing persistence of contrast at these sites of suspected small extravasation. ( e ) Left internal iliac angiography following nonselective embolization of the left internal iliac artery using Gelfoam slurry showing occlusion of all the arterial branches.

Understanding the mechanism of injury and type of fracture can help guide the angiographic evaluation. Young-Burgess classification is the most widely used classification system of pelvic ring fractures ( Fig. 7 ). It is based on the predominant force vectors during trauma: lateral compression, anteroposterior compression, vertical shear, and combined injuries. The type of pelvic fracture may help predict the injured vessel. The lateral compression (side impact) fractures are associated with hemorrhage from the anterior division of the internal iliac artery, most commonly the internal pudendal and the obturator artery. ¹⁹ The anterior posterior compression (open book) fractures are mostly associated with injury of the posterior division of the internal iliac artery, with the superior gluteal and lateral sacral arteries being the most commonly injured arteries. The superior gluteal artery is particularly at risk of injury with fractures of the greater sciatic notch. ²⁰

Fig. 7.

Illustration of Young-Burgess classification. The arrow indicates the predominant force vector during trauma. (Illustration by Dr. Husameddin El Khudari).

Embolic Agents

If embolization is indicated, the choice of embolic agent depends on the type of injury, the vessel involved, the extent of injury, collateral supply, and the clinical condition of the patient. Gelatin sponge (Gelfoam; Upjohn, Kalamazoo, MO) is a temporary embolic agent derived from a biologic substance made of purified skin gelatin. Gelatin sponge is the embolic agent of choice in most of the cases, as it is widely available, inexpensive, easy to use, and produce mechanical occlusion providing rapid control of hemorrhage in unstable patients. It is particularly useful in patients with multiple bleeding vessels and in patients with coagulopathy, as its mechanism is independent on the patient's own coagulation. Additionally, being a temporary agent, Gelfoam allows the body to heal injured vessels and maintain normal blood flow, once these vessels recanalize after several days or weeks. ^{21 22}

The most commonly used form is the sheet or block of Gelfoam, which is cut with scissors into small 1- to 2-mm cubes. Gelfoam slurry is produced by rapidly mixing these Gelfoam cubes with 10 to 20 mL of contrast through a three-way stopcock between two 20-mL syringes. When the Gelfoam is pumped forcefully through the stopcock, a significantly higher number of less than 500-μm particles is created. ²³ Small aliquots of this slurry can be injected using 1- to 3-mL syringe under fluoroscopic guidance. The Gelfoam slurry can be administered through a 4- or 5-Fr catheter when embolizing the internal iliac artery or its anterior or posterior divisions; however, it can also be injected through a 2- to 3-Fr microcatheter when distal selective embolization is performed to avoid occlusion of the main artery by the larger catheter which limits particles flow. Additionally, the use of microcatheter to perform selective embolization into the targeted vessel minimizes nontarget embolization. The main disadvantage of Gelfoam is that the sizes of the particles are not uniform. Additionally, clot disruption with rebleeding is possible. Gelfoam powder with particle size of 40 to 60 µm should be avoided, as they can occlude the arterioles and provide distal capillary occlusion that might lead to skin necrosis.

Alternative embolic agents include particles. Particles are more uniform in size and produce permanent embolization by mechanical occlusion and by producing inflammatory changes in the vessel wall. Particles include polyvinyl alcohol, tris-acryl gelatin microspheres, and hydrogel particles. They are usually produced with calibrated sizes that span a 200-µm range, for example, 100 to 300 µm. The embolization mixture is prepared by mixing these particles with contrast according to the manufacturer's recommendation. Small aliquots can be injected using a 1-mL syringe. Constant remixing and agitation prior to injection is required to prevent particle aggregation.

Metallic (stainless steel or platinum) coils and vascular occlusion plugs can be used for more focal injuries, pseudoaneurysm, or transected vessels. Coil embolization of focal bleeding point requires arterial occlusion both proximal and distal to the site of injury to prevent persistent bleeding through collateral circulation, known as back door bleeding. This requires crossing the area of injury, which is feasible when dealing with a pseudoaneurysm but may be challenging in cases of vessel transection. Both pushable and detachable, macro and micro, fibered coils can be used. The fibers attached to these coils increase their thrombogenicity and improve their performance. Coils need intact coagulation system to produce thrombus at the site of embolization. Patients with coagulopathy may require reinforcement of the coils by Gelfoam slurry injection. In general, coils should be sized according to the target vessel size, and softer coils can be oversized by 20 to 30%. Vascular plugs should be oversized by 30 to 50% of the vessel diameter. ²³ The use of vascular plugs requires a guiding catheter or sheath be placed in the target artery, and the plug is deployed by unsheathing it. Because of the relatively large delivery system, vascular plugs are mainly used for transected large vessels such as the internal iliac artery. Microvascular plugs are now available and can be delivered through microcatheters, which allows their use in distal territories to minimize nontarget embolization.

Liquid embolic agents are rarely used in trauma and include N-butyl cyanoacrylate (Trufill NBCA; Cordis Neurovascular, Miami Lakes, FL) and ethylene vinyl alcohol copolymer (Onyx; Micro Therapeutics, Inc., Irvine, CA), which are mixed with ethiodized oil and dimethyl sulfoxide (DMSO), respectively. They produce fast occlusion which is dependent on the concentration of the active agent in the mixture. Occlusion of the vessel is independent of the patient's coagulation system. Despite these advantages, their use is limited by the high cost of these embolic agents, and the need for an experienced interventionist to avoid reflux and nontarget embolization. ^{5 23}

Other liquid embolic agents such as absolute alcohol and other sclerosing agents are not used in trauma, due to the risk of tissue necrosis. When large nonexpendable vessels are injured such as the abdominal aorta, common iliac, external iliac, or femoral arteries, surgical repair or stent graft placement should be considered.

Complications

Failure to control the hemorrhage is a major complication of pelvic angiography and embolization. This may be the result of extensive injuries in a poly trauma patient, or, rarely, due to the inability to safely perform the embolization if the targeted bleeding vessel was not adequately accessed.

Recurrent hemorrhage requiring a repeat intervention is the most common complication. These may be due to a new bleeding site that was not seen on initial intervention, rebleed from early recanalization of an embolized artery, the use of temporary embolic agent such as Gelfoam, or persistent bleeding from a missed injury. Repeat embolization is reported in 7 to 11% of the patients. ^{5 14 24}

Less commonly reported complications include ischemic necrosis of the gluteal and perineal muscles or skin and necrosis of the rectum. Rare cases of bladder ischemia, and avascular necrosis of the femoral head, have also been reported. ^{25 26} However, in most of the reported cases of ischemic necrosis attributed to bilateral internal iliac artery embolization, the effect of the embolization cannot be separated from the original injury and the operative interventions which affect tissue viability. A recent study of 61 patients who underwent bilateral internal iliac artery embolization for pelvic trauma using Gelfoam slurry with additional coil embolization in selected patients, at a level 1 trauma center over a 20-year period, reported no ischemic complication related to bilateral internal iliac artery embolization. ¹⁴ An earlier study reported similar results with no ischemic complication in a cohort of 70 patients who underwent bilateral internal iliac artery embolization using Gelfoam slurry. The study concluded that bilateral internal iliac artery embolization using Gelfoam slurry and avoidance of vasopressors prior to embolization minimize the risk of gluteal necrosis. ²⁷

Peripheral nerve injury leading to paresthesia and/or paresis is another less common but reported complication. ²⁸ The risk of erectile dysfunction or impotence with bilateral internal iliac artery embolization is not clear as there are other frequent causes for impotence in pelvic trauma patients, such as urethral and nerve injuries. ^{29 30 31} Contrast allergy, contrast-induced nephropathy, access-site infection, hematoma, and pseudoaneurysm formation are other potential complications.

Although there is no significant difference in mortality or transfusion requirement, or the rate of embolization-related complications between nonselective embolization of the internal iliac arteries and more selective distal embolization, it is recommended to perform selective or superselective embolization of more distal vessels to decrease nontarget embolization. ¹⁸

Selective or superselective embolization also decreases the risk of surgical-site infection in patients who require subsequent internal fixation (osteosynthesis). ³² Timing of the intervention is an important predictor for the outcome. Higher mortality is seen in patients arriving late in the angiography suite than those arriving within 60 minutes. ³³

Conclusion

Management of pelvic trauma patients with retroperitoneal hemorrhage requires a multidisciplinary approach. Transcatheter angiography and embolization provides rapid, safe, and effective treatment for pelvic trauma patients with arterial hemorrhage. In hemodynamically unstable patients who need emergent bleeding control, the pelvis should be stabilized by a pelvic binder and the patient taken to the operating room for preperitoneal pelvic packing followed by transcatheter embolization. Those patients, who are responsive to resuscitative efforts and are hemodynamically stable, should be offered transcatheter embolization first. The decision to perform selective or nonselective embolization depends on the level of urgency and the type of vascular injury, and management should be tailored to individual patients. Early percutaneous endovascular intervention is very critical to minimize morbidity and mortality.