Retroperitoneal Bleeding

Etiology

Complicating the diagnosis of retroperitoneal bleeding is a myriad of etiologies. The most commonly described initial delineation of causes is whether a patient’s bleeding is associated with trauma or not.[2][3][4] Traumatic causes include penetrating and blunt trauma, typically of the abdomen and pelvis, whereas non-traumatic causes are divided into those occurring spontaneously and those not occurring spontaneously. Spontaneous etiologies are more varied and include patients undergoing anticoagulation or fibrinolytic therapy. Patients with hemorrhagic pancreatitis, renal or adrenal malignancies, gynecological complications, and aneurysmal dilations of the aortic and renal arteries may also experience spontaneous hemorrhage into this potential space.[5] Nonspontaneous causes include iatrogenic injury during aortic and femoral artery cannulation or direct injury during abdominal or pelvic exploration.[6][7]

Epidemiology

Damage to retroperitoneal structures following abdominal trauma is common. Authors have reported some 20% to 33% of patients with penetrating trauma and 44% to 80% of those with blunt trauma experience retroperitoneal injury with an overall associated mortality rate of 18% to 60%.[2][3][8]

Spontaneous hemorrhage is a considerably more rare phenomenon. Clinical trials of anticoagulation-induced hemorrhage of the retroperitoneum have documented a rate of 0.6% to 6.6%, with mortality occurring in 20%. In 1 study, following a percutaneous coronary intervention, iatrogenic retroperitoneal bleeding was noted in 0.57% of patients with an associated mortality rate of 10.4%.[9][10]

History and Physical

Retroperitoneal bleeding is a life-threatening condition. Diagnosis is difficult even for the astute clinician as the presentation can be variable and nonspecific. Accurate diagnosis requires a high clinical index of suspicion and an accurate and focused history and physical examination. Rapid elucidation of recent trauma, known malignancy, recent surgical procedures, history of aneurysmal disease, current use of anticoagulation, and ongoing pancreatitis are keys to narrowing a wide differential diagnosis.[1]

The most common presentation of bleeding into the retroperitoneal space is abdominal or flank pain.[5][9] This may be accompanied by femoral nerve palsies in 20 to 30% of cases or radiation of pain into the groin or pelvis. Presentation exists on the spectrum of hemorrhagic shock, with patients demonstrating anxiety and tachycardia early on in the disease process and hypotension, confusion, and later hypothermia. Physical examination in some cases may demonstrate the “Wunderlich syndrome,” described as abdominal, back, flank, or groin pain, a palpable abdominal mass, and shock.[9][11]

Eponyms abound in the description of abdominal bleeding and are of use in a minority of cases. Grey-Turner’s sign occurs when a hematoma is developed along the lateral abdominal wall, secondary to perirenal space bleeding tracking along with the quadratus lumborum. Cullen’s sign is a periumbilical ecchymosis developing anteriorly when retroperitoneal bleeding dissects along the falciform ligament. Fox’s sign is ecchymosis of the anteromedial thigh from blood tracking along the psoas and iliacus muscles’ fascial planes. Bryant’s sign occurs when the scrotum fills with blood and becomes ecchymotic from abdominal bleeding tracking along the spermatic cord. Finally, Stabler’s sign is the development of a hematoma and bruising overlying the inguinal ligament.

In some cases, symptoms may be absent or overshadowed by other distracting injuries, particularly in trauma. Here, careful attention must be paid to the mechanism of injury and commonly associated injuries. Genitourinary involvement of bleeding may manifest as hematuria, while oliguria may develop from adjacent extrinsic compression by a developing hematomal mass. Additionally, pancreaticoduodenal involvement can present with gastric outlet obstruction.

Evaluation

The most useful laboratory measurement to narrow the differential diagnosis towards retroperitoneal bleeding is falling hemoglobin; however, it must be emphasized that patients bleed whole blood, so it may take some time with or without crystalloid volume resuscitation to recognize this acute hemorrhagic anemia. Other useful studies include prothrombin time, partial thromboplastin time, international normalized ratio, and thromboelastography to identify a patient’s anticoagulation status. Urine analysis can evaluate for urinary tract involvement. A blood type and crossmatch are essential if bleeding is suspected or ongoing.

The focused assessment with sonography for trauma (FAST) has profoundly altered the approach to the diagnosis and management of abdominal trauma. Unfortunately, 1 well-documented profound shortcoming of abdominal ultrasonography is the inability to evaluate the retroperitoneal space effectively. Because of this, ultrasound remains an incredibly useful tool for evaluating concomitant free fluid in the peritoneal space but cannot be reliably used to rule in or out retroperitoneal bleeding. The FAST exam is also limited in several other ways.[12] It cannot identify an intraperitoneal fluid volume of less than 200 mL, nor differentiate between different fluid types, such as blood, urine, or stool.[13]

Also common in the trauma bay are the routine cervical, chest, and pelvic roentgenograms. A pelvic fracture may be the clinician’s first indication that the inferior retroperitoneum is involved; however, outside of the trauma setting, roentgenograms lack usefulness. The computed tomographic (CT) cross-sectional imaging of the abdomen with intravenous contrast has been identified as the superior study for narrowing the broad differential associated with retroperitoneal bleeding. CT can easily, rapidly, and repeatedly identify the specific hematomal location and concomitant injuries and determine if bleeding is ongoing.[14][15]

CT examination is not without its negatives. The scan utilizes ionizing radiation, which can predispose a patient to develop cancer at a later date. The use of intravenous contrast can cause an acute kidney injury. Evaluating pregnant women and children should emphasize studies that forgo ionizing radiation, such as abdominal ultrasonography and magnetic resonance imaging.

Treatment / Management

The treatment of retroperitoneal bleeding can be thought of in a stepwise approach, from nonoperative management to angioembolization or, in severe cases, surgical intervention. The determination of the specific treatment strategy depends on several factors, including the location of the retroperitoneal bleeding, the patient’s stability, and the etiology of the bleeding. In all cases, regardless of whether or not trauma has proceeded to the initiation of bleeding, initial resuscitation must begin with the use of the “ABCDEs” of trauma. Simultaneous with implementing this algorithmic resuscitative approach, the search for the etiological cause and assessment of patient stability is undertaken. If, at any time, the patient is noted to be hemodynamically unstable or demonstrates peritoneal signs, an urgent surgical intervention must be considered. Other indications that warrant immediate surgical intervention in trauma are based on the location of bleeding, which is discussed here.

The retroperitoneum has been described as having 3 anatomical zones. Zone 1 is centrally located in the upper retroperitoneum and includes the aorta, inferior vena cava, pancreas, esophagus, and duodenum; zone 2 is located laterally to zone 1 and includes the ascending and descending colon, the kidneys and their ureters, and the adrenal glands; finally, zone 3 is located across the inferior portion of the retroperitoneum and contains the iliofemoral vessels as well as the rectum.

When retroperitoneal bleeding has been identified in trauma, the mechanism guides management. With penetrating trauma, zones 1 and 3 should be immediately surgically explored in all cases. Zone 2 is explored if bleeding is noted to be ongoing. In blunt trauma, zone 1 is always explored, and zone 2 is explored if bleeding is noted to be ongoing; however, if zone 3 bleeding is identified, surgical intervention should not be attempted in the setting of blunt trauma as the typical source is a pelvic fracture and associated venous plexus bleeding. Exploration can worsen bleeding by disrupting the partially formed coagulum and removing the hematomal tamponade.

Next, we briefly discuss the primary survey of trauma resuscitation. The primary survey can be easily remembered using the “ABCDE” mnemonic. This begins with assessing the patient’s airway, “A,” to determine if it is patent. This is followed immediately by confirmation that the patient is breathing “B.” If either a patient’s airway or breathing has been compromised, rapid intubation should be performed to maintain sufficient oxygenation and ventilation. Next, “C” stands for the obtainment of vascular access and maintenance of circulation. Massive transfusion protocol should be initiated early if bleeding is profound, especially if a patient’s presentation is concerning for hemorrhagic shock. Fluid resuscitation should follow trauma guidelines with no more than 2 liters of crystalloid fluid administration before transfusing packed red blood cells, platelets, and plasma in a 1 1:1 ratio.[16]

Assessment of patient disability, “D,” then occurs and includes performing a Glasgow coma scale, spine sweep, and assessing pupils for size and reactivity to light. Finally, one must completely expose “E,” the patient’s skin, and remove their clothing to complete a comprehensive physical exam. In retroperitoneal bleeding, emphasis is placed on the abdominal exam. The astute clinician must also elucidate a focused history, typically described by the acronym “SAMPLE,” consisting of the patient’s symptoms, allergies, medications, past medical history, last meal, and events proceeding their presentation. Reversal of anticoagulation, administration of blood products, and identification of concurrent pathology are paramount to the initial assessment.

If bleeding is ongoing and the patient is sufficiently stable, angioembolization may be employed. During this procedure, a catheter is introduced into a more peripheral artery, most commonly the femoral artery, and advanced retrograde to the area of suspected bleeding. Radiopaque contrast is infused, and image processing, such as digital subtraction angiography, allows the vascular flow and potential extravasation of contrast to be identified. The benefit of defining vascular injury with interventional angiography over CT angiography or magnetic resonance angiography is the possibility for immediate intervention. Once an injury is identified, hemostasis is achieved through a coil or particle embolization. Repeat contrast investigation demonstrates cessation of bleeding.[17][18](B2)

Frequent reassessments are paramount to successful outcomes for all patients with retroperitoneal bleeding, especially those managed nonoperatively. Nonoperative management includes the reversal of anticoagulation, crystalloid and blood product resuscitation, serial abdominal examinations, and etiological identification of bleeding. Once an underlying cause is known, it should be reversed or corrected. During all stages of the resuscitative process, careful attention must be paid to the patient’s vital signs, particularly blood pressure and heart rate, as retroperitoneal bleeding can be a dynamic process from which patients may deteriorate despite resuscitative efforts.[19](B2)

Differential Diagnosis

Injury to the retroperitoneum can result in damage to any of the organs of this space, including the adrenal glands; aorta; inferior vena cava; second and third parts of the duodenum; pancreatic head, neck, and body; ureters; ascending and descending colon; kidneys; esophagus; and rectum. These injuries may exist in isolation or, especially in the case of trauma, exist with other retroperitoneal, abdominal, spinal, or pelvic injuries.[2]

When spontaneous retroperitoneal bleeding is identified, the search for concomitant pathology that may be the source of the bleeding must ensue. This includes assessing for anticoagulation use, recent fibrinolytic therapy, renal masses, adrenal masses, gynecological complications, pancreatitis, or aortic and renal aneurysms.[4][5][6]

In the event of iatrogenically induced retroperitoneal bleeding, the specific location of bleeding must be identified. Here, the specific catheterization pathway utilized by the performing proceduralist must be sought, as the nidus of bleeding initiation most likely has been initiated along this pathway. A complete vascular analysis is key to assess for vascular rupture, dissection, pseudoaneurysm, fistula, or wall hematoma.

Prognosis

Traumatic retroperitoneal hemorrhage has a high associated degree of mortality, with an overall rate of approximately 18%. More deadly injuries were identified to be those from blunt trauma, injuries of 2 or more retroperitoneal zones, and those who received surgical intervention more than 6 hours after injury.[3]

As the causes of spontaneous retroperitoneal bleeding are diverse and wide-ranging, so are the clinical outcomes. A large majority of patients respond to medical management alone. Of those with ongoing bleeding and worsening symptoms, approximately 25% receive angiographic therapy as definitive management, and an additional 9% need surgery. All-cause mortality ranges from as low as 6% to as high as 22% overall.[5][6][9] The most common location of spontaneous retroperitoneal bleeding is Zone 3, and those that die while suffering a bleed, typically due so to another condition occurring in conjunction with their bleeding.[20]

Complications

There are a variety of complications that can occur as a result of retroperitoneal bleeding. A brief list is provided based on the original insult and most common sequelae. Complications from hematomal formation mass effect include pelvic/ femoral neuralgia, small bowel obstruction, urinary obstruction, and gastric outlet obstruction.[11]

Complications from the associated hypotension, hypovolemia, and shock that can develop with severe retroperitoneal bleeding include myocardial infarction, acute kidney injury, acute liver injury, diffuse cerebral hypoperfusion, global hypoxia, and bowel necrosis.[9]

Complications of surgical intervention include infection, damage to adjacent structures of the operative field, and worsening of bleeding. Complications of angioembolization include infection, damage to the vasculature, worsening of bleeding, contrast-induced nephropathy, and ischemia of embolized arterial distributions.