Indications

Angiography and possibly endovascular intervention are indicated in the setting of known or suspected pelvic hemorrhage due to blunt or penetrating pelvic trauma.1–4 Preprocedural dynamic contrast-enhanced CT, with acquisitions in both the arterial and venous phases, is extremely useful in selecting patients and planning the procedure. CT findings of vascular injury in the setting of pelvic trauma may range from normal or nearly normal to signs of previous or active bleeding, such as intraperitoneal and retroperitoneal blood, vascular pseudoaneurysms, and frank extravasation. In addition, the soft tissue and skeletal injuries accurately depicted on CT frequently provide a clue to the site of the injured vessel. CT is accurate in demonstrating intraabdominal solid organ visceral trauma that may require open exploration before angiography. Despite the accuracy of CT, however, it is useful to remember that these images represent merely a snapshot in time in the evolution of injury in a trauma patient. Angiography may therefore be indicated because of the mechanism of injury or clinical deterioration in a previously stable patient in whom CT did not demonstrate active hemorrhage. Vascular injury in patients undergoing angiography in the setting of pelvic trauma may include the gamut of small- to medium-vein and small arteriole and capillary transection or injury, often not seen on angiography, to medium- to large-artery pseudoaneurysms, stretch injuries, dissections, and vascular truncations. These larger arterial injuries may produce a complicated clinical course that is often characterized by alternating periods of relative stability and rapid destabilization. These patients may require emergency angiography and intervention without repeat CT imaging.

To summarize, indications for angiography and embolization in the setting of pelvic trauma include⁵:

Contraindications

Contraindications to angiography and endovascular intervention may include acutely unstable patients with multisystem trauma. Such patients may have multiple sites of potential hemorrhage, including the pelvic vessels and solid organs such as the spleen, liver, and kidney. These unstable patients may have such overwhelming acute blood loss that they may best benefit from acute operative exploration or “damage-control surgery,” followed by angiography and endovascular intervention. Adjunctive pelvic packing, as part of a damage-control protocol, may be effective in achieving rapid hemostasis in hemodynamically unstable patients with pelvic ring injuries and may either preclude the need for embolization or play a complementary role with subsequent endovascular treatment.6,7 In addition, in patients with acute intraperitoneal hemorrhage, the peritoneal cavity may be rapidly distended with blood and result in an abdominal compartment syndrome that may severely inhibit blood return via the inferior vena cava and perfusion to visceral organs, and restrict ventilation secondary to diaphragmatic elevation and the resultant reduction in tidal volume and high airway pressure. These patients may require open exploration and intraperitoneal clot extraction for stabilization before the endovascular procedure.

Patients with altered vascular anatomy due to previous vascular surgery (e.g., aortobifemoral bypass, interventions such as endovascular repair for abdominal aortic aneurysm) may represent a relative contraindication because of severely altered anatomy. In general, however, these patients typically may present challenges with respect to vascular access and selective catheterization, but endovascular therapy is not precluded because of the frequent preservation of pelvic vessels.

In the setting of trauma and acute blood loss, patients can suffer loss of coagulation proteins, platelet deficits, and other associated factors such as hypothermia that can lead to rapid development of an acquired coagulopathy. Even though the degree of coagulopathy can be severe, it remains more of a management challenge than a contraindication. Access site complications can be minimized by using closure devices when appropriate, or by leaving a vascular sheath in place until the coagulopathy can at least be partially corrected.

Some patients may have a relative contraindication to the use of iodinated contrast material, either because of a previous history of a severe contrast agent reaction or because of marginal renal function, particularly in the setting of long-standing insulin-requiring diabetes mellitus. In clinical practice in the acute setting, it is rare that we have sufficient history to document a previous life-threatening reaction to iodinated contrast material. Use of iodixanol (Visipaque), an iodinated monomeric isoosmolar contrast agent, may minimize the potential for reaction to contrast media and for contrast medium–induced nephropathy.⁸

In the setting of femoral neck fracture, embolization of the ipsilateral superior gluteal artery or the ipsilateral posterior division of the internal iliac artery may be associated with delayed bone healing after orthopedic interventions on the femur or with avascular necrosis.⁹ In these situations, however, it is unclear whether there is a clinical difference between permanent coil occlusion or Gelfoam embolization of posterior division vessels.

Equipment

Fixed equipment for diagnosis and intervention in patients with pelvic hemorrhage includes an angiographic system, typically equipped with a large–field of view flat-panel detector or image intensifier capable of high–frame rate 1024 × 1024 digital subtraction angiography and high-quality magnification fluoroscopy. These systems are discussed in more detail in previous chapters. Newer systems equipped with flat-panel detectors are capable of rotational acquisitions that produce CT-like cross-sectional data. In the setting of pelvic hemorrhage, this capability may be useful in confirming treatment of a site of hemorrhage seen on preprocedural CT. Refinement of the use of these flat-panel CT acquisitions will require further clinical study. In addition, the system should be equipped with barrier radiation protection devices for both the patient and operator, and dose-saving technology such as last image hold, variable frame rate, and variable-dose fluoroscopy.

Typical catheters used for pelvic angiography and interventions include 4F and 5F pigtails, reverse-curve Simmons 1 and SOS catheters, and angled catheters such as the Cobra C2, Berenstein, and vertebral curve catheters. Most diagnostic angiography will be done via pigtails or 0.035/0.038-inch (inner diameter) catheters because of the need for injections at relatively high flow rates. Coaxial microcatheters are often used for selective and superselective applications. We prefer 0.018- to 0.021-inch (inner diameter) microcatheters because of the ability to deploy embolization microcoils, the newer detachable coils, and Gelfoam slurry or small pledgets if needed. Larger-lumen, 0.027-inch (inner diameter) microcatheters offer the advantage of higher contrast material flow rates but may be suboptimal for microcoil deployment because of their larger lumen, which at times does not adequately constrain the coil and results in difficulties in deployment.

Embolization procedures generally involve the use of coils or Gelfoam for vascular occlusion. Spherical embolic material is available in a wide range of sizes and may occasionally be used (discussed later). Embolization coils may include 0.035-inch-diameter stainless steel or fibered platinum coils or 0.018-inch-diameter fibered platinum or fibered detachable coils. When a discrete area of extravasation or pseudoaneurysm is identified and the patient’s clinical condition permits, selective coil embolization is preferable to regional particulate embolization. Gelfoam pledgets or slurry may be used as an adjunct to selective distal coil embolization or may be used as primary treatment to achieve rapid vascular occlusion in the setting of severe hemodynamic instability.

As mentioned previously, nonionic contrast material is used exclusively for both diagnosis and intervention in pelvic hemorrhage. In the acute posttraumatic setting, iodixanol, a monomeric isoosmolar agent, is used because of a slightly lower incidence of contrast medium–induced nephropathy. In a stable, non–volume-depleted adult, dimeric nonionic agents such as iohexol may be used. In patients with marginal renal function, iodixanol is our iodinated contrast agent of choice. Carbon dioxide may be substituted in these settings to reduce the total load of iodinated contrast material, but it is usually limited to large-vessel injections and proximal internal iliac arteries. (Note: In trauma patients, CO₂ should only be used below the level of the diaphragm because of the potential risk of stroke.) We prefer the use of iodinated contrast agents for selective and superselective pelvic angiography to confirm the site of vessel injury and guide the deposition of embolic material.