PELVIC BLEEDING: MAKING THE DIAGNOSIS

There are four cavities into which a patient can exsanguinate—thorax, abdomen, retroperitoneum, muscle compartments, as well as externally. While bleeding into the mediastinum or into the brain may be life threatening, only a small volume is required to produce symptoms. Thus, exsanguination into these regions is not possible.

The diagnosis of intrathoracic bleeding can be made with a combination of physical exam and a chest x-ray or ultrasound exam. Tension pneumothorax and/or massive hemothorax can be identified rapidly. Muscle compartment bleeding should be identifiable on physical exam. Finally, external blood loss can generally be diagnosed by history. In addition, external blood loss may become apparent for the second time as the patients are resuscitated and blood pressure increases.

The distinction between intra-abdominal and retroperitoneal bleeding can be most difficult. Combined abdominal and pelvic injuries are common. Physical findings such as abdominal pain, distention, or tenderness do not differentiate between intra-abdominal or retroperitoneal bleeding. In addition, physical findings can be quite nonspecific. Patients can bleed a large volume of blood into the abdomen and/or retroperitoneum with minimal physical findings.

In the past, the diagnosis of intra-abdominal injury was generally made by diagnostic peritoneal lavage in patients who were hemodynamically labile. The advent of the focused ultrasound exam however, has revolutionized the early diagnosis of intra-abdominal injury. The focused assessment with sonography for trauma (FAST) is a rapid bedside technique that can make the diagnosis of intraabdominal injury in several minutes. FAST is portable and can be repeated if results are equivocal.

While FAST is rapid, it is nonspecific. It can identify the presence of blood but is not an organ-specific test. Computed tomography (CT) scanning allows imaging of both the intra-abdominal as well as retroperitoneal structures. It can identify blood loss into both compartments. Unfortunately, this is not nearly as rapid as the FAST exam and is of limited utility in patients who are hemodynamically unstable.

The presence of retroperitoneal hemorrhage should be suspected in any patient with a pelvic fracture. A pelvic x-ray is a rapid screening test that should alert the clinician to the possibility of pelvic hemorrhage. This is usually performed as the screening radiograph with a chest x-ray. After blunt trauma, patients can bleed into the retroperitoneum without a pelvic fracture, but this is exceedingly rare. While a pelvic x-ray is a good screening test, it only describes pelvic anatomy in two dimensions and can vastly underestimate the degree of a pelvic bony injury posteriorly.

Initial physical exam of the pelvis can be helpful in determining skeletal stability even before an x-ray is taken. While some advocate rocking the pelvis vigorously, we believe that this is a potentially dangerous maneuver. In patients with skeletally unstable pelvic fractures, this produces excruciating pain. In addition, displacement of the fracture fragment may exacerbate bleeding that had stopped. Instead, we encourage clinicians to gently compress the pelvis inward at the level of the iliac crest. If the pelvis is skeletally stable, it will not give. If there is give in the pelvis, the patient almost certainly has a skeletally unstable pelvic fracture.

It is important to distinguish between patients with skeletally unstable pelvic fractures and patients who are hemodynamically unstable. Skeletal stability describes the bony architecture of the pelvic fracture. Hemodynamic stability describes the patient’s physiologic response. Not all patients with skeletally unstable pelvic fractures are hemodynamically unstable. In addition, patients who have skeletally stable fractures can still lose a substantial amount of blood into their retroperitoneum.

Patients with a pelvic fracture, a positive FAST, and hemodynamic instability are almost certainly best served by an immediate laparotomy. In most patients, the FAST turns positive with 200–300 cc of fluid in the abdomen (Figure 1). While free fluid could certainly be from a relatively minor intra-abdominal injury or a ruptured hollow viscus such as the bladder, diagnostic laparotomy is probably the most rapid and definitive test in patients who are hemodynamically unstable. If minor injury is found and bleeding is thought to be coming from the pelvis, abbreviated laparotomy should be performed and other plans made to control the pelvic bleeding.

Figure 1 Fluid in the abdomen can signal a positive focused assessment with sonography for trauma (FAST), pelvic fracture, and hemodynamic instability. Such patients are almost certainly best served by an immediate laparotomy.

PELVIC FRACTURE CLASSIFICATIONS

A number of classification schemes are available that describe the bony architecture of pelvic fractures. Probably the most commonly used scheme was described by Young and Burgess in 1986 and classifies pelvic fractures by their vector of force (Table 1). Each classification is subdivided to describe the degree of pelvic instability. The authors originally thought that this classification scheme could predict the need for transfusions. While this may actually not be the case, it is quite useful in describing fracture anatomy and guiding initial attempts at hemostasis.

Table 1 Classification of Pelvic Fractures

Data from Young JWR, Brumback RJ, Poka A: Pelvic fractures: value of plain radiography in early assessment and management. Radiology 160:445, 1986.

Lateral compression (LC) pelvic fractures caused by side impact generally occur after T-bone vehicular crashes or car–pedestrian collisions (Figure 2). LC fractures cause an acute shortening of the pelvic diameter. The pelvis does not open but closes down. The pelvic ligaments generally stay intact. Thus, these fractures generally do not bleed. Hemodynamic instability after a lateral compression fracture more likely results from torso injuries such as intra-abdominal bleeding or intrathoracic bleeding. There is a known association with traumatic aortic injury and LC pelvic fractures.

Figure 2 Lateral compression pelvic fracture.

(From Moore EE, Feliciano DV, Mattox KL: Trauma, 5th ed. New York, McGraw-Hill, 2003.)

Anteroposterior compression (AP) fractures generally occur after head-on vehicular crashes or may occur after equestrian injury, typically when patients are thrown from a horse or the horse lands on them (Figure 3). With this mechanism, pelvic diameter widens and the pelvis opens. The injuries can be purely ligamentous if the sacroiliac (SI) joints rupture, even in the absence of significant bony injury. Pelvic vascular injuries are quite common. AP compression fractures have the highest chance of bleeding, and transfusion requirements are the greatest in patients with these fractures.

Figure 3 Anterior/posterior compression fracture.

(From Moore EE, Feliciano DV, Mattox KL: Trauma, 5th ed. New York, McGraw-Hill, 2003.)

Vertical shear (VS) injuries occur when patients land on an outstretched foot, which generally occurs after falling from a height (Figure 4