Pelvic Trauma

Abstract

The leading cause of death in the pediatric population is trauma, of which pelvic injuries make up a very small percentage. Trauma to the pelvis can result in multiple injuries to the bony pelvis, rectum, bladder, and or the urethra. Although mortality in the pediatric population is typically secondary to associated injuries, pelvic hemorrhage can be a life-threatening event. The management of patients with complex pelvic injuries requires a multidisciplinary approach in order to achieve the best possible outcomes.

Introduction

Trauma is the leading cause of death in the pediatric population of which pelvic trauma makes up a very small percentage. There is a large disparity between incidence and severity of injury of pelvic injuries between the adult and pediatric population. Approximately 9% of all patients with blunt trauma have an associated pelvic injury with a mortality of 6% in patients with pelvic ring fractures. Another 39% of deaths are associated with uncontrolled pelvic hemorrhage. When looking specifically at the pediatric population, the reported incidence of pelvic injuries is 2.4 to 7%.^{1 2 3 4 5} Mortality of patients with pediatric trauma with pelvic injuries range from 1.7 to 11.1%, most of which are because of the associated injuries.^{1 2 5} In 5 reviews of 1,000 pediatric patients, a total of only 4 (<1%) patients were reported to have died as a direct result of pelvic fracture-induced exsanguinations.^{1 2 5 6}

Anatomy of Pelvis

The bony pelvis is what defines the abdominal pelvis (containing rectum, bladder, urethra, small intestine, uterus, fallopian tubes, and ovaries). The pelvic ring is formed by the sacrum, two innominate bones with anterior and posterior sacroiliac (SI) ligaments providing vertical stability across the SI joints.^{7 8} The pelvic floor is comprised of the sacrotuberous and sacrospinous ligaments connecting the sacrum to the ischial spine and ischial tuberosity. The main vascular supply to structures in the pelvis is provided by the internal iliac artery. The anterior division of the internal iliac artery branches into the inferior gluteal, obturator, inferior vesicular, middle rectal, and internal pudendal arteries. The posterior division of the internal iliac artery feeds the iliolumbar, lateral sacral, and superior gluteal arteries. Venous drainage is parallel to the arterial system (however also forms extensive plexus system) that ultimately drains into the internal iliac veins. Disruption of the sacral venous plexus is the most common source of pelvic bleeding after major pelvic fractures.⁷

Bony Pelvic Trauma

When compared to the adult population, patients with pediatric trauma are significantly less likely to sustain pelvic fractures. The immature pelvic bones are less brittle with increased plasticity, thicker periosteum, and increased elasticity of the symphysis pubis and SI joints. With the increased plasticity and elasticity, the pediatric pelvis has a greater absorptive capacity, and a higher energy force is needed to cause a fracture compared to the adult population.^{4 9 10}

Fracture patterns among children can also be dependent on age, and whether or not the triradiate cartilage is open. The triradiate cartilage is the y-shaped growth plate that forms between the ilium, pubis, and ischium forming the cup-like acetabulum of the pelvis. This cartilage usually fuses by the age of 12 years in females and 14 years in males. In the immature pelvis where the triradiate cartilage is not yet definitively fused, fractures typically occur at the pubic rami and iliac wings. In this age group, the iliac wing is weaker than the elastic pelvic ligaments making disruption of the pelvic ring less likely. Once the triradiate cartilage is closed, pelvic bones are stronger than pelvic ligaments making disruption of the pelvic ring more likely. Injuries to the anterior superior iliac spine, ilium, and ischium are much more common in this age group.¹¹ In one retrospective review of 124 children, the majority of patients identified to have pelvic injury were skeletally mature with closure of the triradiate cartilage. These patients were also more likely to have higher grade pelvic fractures than the younger children with an open triradiate cartilage.¹²

Traditionally, pelvic fracture classifications in adults are based according to the direction of the impact force; fractures secondary to anterior–posterior (AP) compression, lateral compression, vertical shear, or a combination of these as described by the Young–Burgess classification (Table 1).

Table 1. Young–Burgess classification of pelvic fractures^a .

Type	Characteristics	Displacement of hemipelvis	Stability
Anteroposterior compression, type I	Symphyseal diastasis (slight widening sacroiliac joint)	External rotation	Stable
Anteroposterior compression, type II	Symphyseal diastasis (widened sacroiliac join)	External rotation	Rotationally unstable, vertically stable
Anteroposterior compression, type III	Symphyseal diastasis with complete sacroiliac joint disruption (anterior and posterior ligament disruption)	External rotation	Rotationally unstable, vertically unstable
Lateral compression, type I	Transverse pubic rami fracture with sacral compression on side of impact	Internal rotation	Stable
Lateral compression, type II	Transverse pubic rami fracture with iliac wing fracture	Internal rotation	Rotationally unstable, vertically stable
Lateral compression, type III	Transverse pubic rami fracture with contralateral anteroposterior compression injury	External rotation	Rotationally unstable
Vertical shear	Anterior vertical fracture, (typically through sacroiliac joint)	Vertical displacement	Rotationally unstable, vertically unstable

^aAdapted from Velmahos and Burgess et al.^{7 13}

AP compression fractures occur in the sagittal plane, typically secondary to motor vehicle crashes. These fractures can involve diastasis of pubic symphysis, which may or may not be associated with anterior SI widening and posterior instability, or can lead to SI joint disruption. The hemipelvis is typically rotated externally, and depending on type of AP fracture, may or may not be stable.

Lateral compression fractures result when the force of impact occurs across the horizontal plane. These types of injuries are typically seen with motor vehicle collisions involving a side impact (such as T-bone collision). These fractures involve sacral or iliac wing compression on the side of impact. Depending on the severity of the impact, these fractures result in internal rotation of the hemipelvis and can lead to instability of the pelvis as well.

Vertical shear fractures involve vertical displacement anteriorly through the pubic symphysis and posteriorly through SI joint, iliac wing, or sacrum. These fractures typically result from high falls. These injuries result in vertical displacement of hemipelvis and are typically considered unstable pelvic fractures. Approximately, one-third of patients have a combination of AP, lateral, or vertical fractures.⁷ This classification system has been demonstrated to be useful in predicting transfusion requirement and mortality in the adult population. Patients with lateral compression, type II, lateral compression, type III, AP compression, type II, and AP compression, type III fractures had significantly higher rate of transfusion requirements. According to this classification scheme, patients with an unstable pelvis had a significantly higher rate of mortality (11.5%) compared with those with stable pelvic fractures (7.9%).¹⁴

The fracture pattern between children and adults also vary secondary to variations in mechanism of injury. Children with pelvic fractures are typically passengers or pedestrians hit by motor vehicles causing lateral compression injuries without disruption of the SI joint. Lateral compression decreases pelvic volume and is typically not associated with significant hemorrhage. Adults on the contrary are typically drivers or front seat passengers leading to AP compression of the pelvis with increase in pelvic volume. This is associated with SI joint disruption and a higher likelihood of pelvic-related vessel injury.¹⁰

Because fracture patterns can vary so widely with patient age, there is no ideal classification system for all patients. The most commonly used pediatric pelvic fracture reference is the Torode and Zieg¹¹ classification system (Table 2). Increasing severity based on this classification system is associated with increasing morbidity as well as mortality. Patients with type IV fractures were also more likely to require blood transfusions. The most commonly associated morbidity associated with pelvic injuries in the original study was found to be neurologic (56%).¹¹ In one review of 2,248 patients admitted to a pediatric trauma center, traumatic brain injury was the cause of death in 83% of those patients with a pelvic fracture.¹

Table 2. Torode and Zieg classification of pelvic fractures.

Type I	Avulsion fracture
Type II	Iliac wing fractures
Type III	Simple ring fractures
Type IV	Pelvic ring disruption

Pelvic Hemorrhage

A mechanically unstable pelvic fracture is known to increase the volume of the pelvis. This increase in space is thought to decrease the tamponade effects of the retroperitoneum, potentially leading to significant bleeding into the pelvic space. The most common source of significant pelvic bleeding has been shown to be injury to the iliolumbar vein seen with fractures of the SI portion of the pelvis. Data from adult cadaveric studies have demonstrated that a 5 cm pubic diastasis can lead to an approximately 20% increase in the volume of the pelvis.¹⁵ Although mortality secondary to pelvic hemorrhage in the pediatric population is rare, because it can lead to significant bleeding, immediate intervention is necessary when it is identified. The treatment algorithm for management of the patient with hemodynamically stable and hemodynamically unstable trauma with pelvic injuries is derived primarily from the adult literature.

There are a number of pelvic compression devices that have been used in the acute setting for open-book pelvic fractures. These devices include the pneumatic antishock garment, the temporary pelvic binder, the pelvic C-clamp, and external pelvic fixation. Pelvic binders are used in the prehospital and emergency room settings as temporary measures to stabilize the pelvis. The purpose of the binder is to prevent movement of fractured elements and decrease pelvic volume thereby creating a tamponade effect to hemorrhage. Stabilization of fractured elements can be achieved with mild-to-moderate lateral compression with the pelvic binder. Hemorrhage control can be achieved with significant lateral compression by reducing the volume of the open pelvis. When the pelvic binder is placed in the acute setting, it is important to be cognizant of the type of fracture that is suspected. For open-book pelvic fractures where reduction of pelvic volume is desired to help create a tamponade effect, a greater amount of lateral compression is necessary. In moderately displaced lateral fractures on the contrary, a moderate amount of pressure may be required to stabilize the fractures. A significant amount of tightening of the pelvic binders can actually have the opposite effect and further displace the fractures, worsening the bleeding. Reevaluation of the level of compression being applied once a pelvic fracture pattern has been identified is critical. When being placed, pelvic binders should be centered around the greater trochanter and not over the iliac spines. The binder is fastened just tight enough to allow two fingers to pass underneath. If placed too high, tightening of the pelvic binder can provide ineffective pelvic stability and excessive abdominal pressure.¹⁶ Duration of treatment with a pelvic binder is also important. Leaving the pelvic binder on for prolonged periods of time can affect peripheral circulation, compromising the integrity of underlying skin, subcutaneous tissue, and muscle, and leading to pressure ulcers. Tissue damage in as little as 2 to 3 hours has been demonstrated to occur at sustained pressures of 9.3 kPa. The pressure applied with the pelvic binders has been shown to range between 3 and 25 kPa over the various pressure points (trochanter, sacrum iliac crest).¹⁷ While it is typically recommended that binders should not be in place for more than 24 to 48 hours, periodic loosening of the binders for brief periods of time at regular intervals of 2 to 3 hours should be considered if the patient's condition allows.^{7 17}

Another form of pelvic stabilization that can be used in the acute setting involves the use of external fixators. External fixation can help stabilize fractured elements and decrease pelvic volume.^{7 18 19} While fixation devices are typically placed in the operating room, with the appropriate sedation, equipment, and personnel, this can be achieved in the emergency room. It is important to note that cadaveric studies have demonstrated that there is no significant difference in pelvic stability achieved with properly placed pelvic binders and external fixators.²⁰ Therefore, at institutions that do not have readily available expertise in placing external fixators in the emergency room setting, pelvic binders should be used as a bridge to placement of external fixators and/or definitive treatment with internal fixation. With regards to patients who need surgical or invasive radiologic intervention, there are data that suggest that patients who undergo laparotomy or angiography before external fixation had higher mortality¹⁹ than those who underwent external fixation alone or external fixation followed by angiography or laparotomy. It stands to reason that reduction of pelvic volume by means of a pelvic binder or external fixation in patients with a vascular injury associated with a pelvic fracture is a critical component to the initial management of these patients. For patients who are considered unstable secondary to other injuries, external fixators can be left in place for 6 to 12 weeks until the patient is stable enough for definitive repair.²¹

Continued pelvic blood loss after stabilization of the pelvic fracture with either a binder or external fixation will require a more invasive approach. Hemodynamic instability or ongoing blood loss in a patient with a pelvic fracture and no other source of bleeding should be considered for emergent pelvic angiography as recommended by the Eastern Association for the Surgery of Trauma management guidelines. It is important to note, however, that the majority of vascular injuries associated with pelvic fractures are venous and therefore angiography and embolization may potentially only benefit a small percentage of these patients. Patients should also be considered for angiography and embolization if arterial intravenous contrast extravasation on pelvic computed tomography (CT) is noted.²² It has been suggested however, that an isolated pelvic blush on an early CT in a hemodynamically stable patient is not always a reliable indicator for the need for pelvic hemorrhage control and a trial of conservative management should be attempted.²³ Although the literature regarding angiography in children is sparse, in one large series of 97 pediatric patients undergoing abdominal or pelvic angiograms, effective hemorrhage control was obtained in 87% of patients (62% of which were pelvic in origin).²⁴ This study demonstrates that in centers with experience in pediatric angiography, this modality can be considered a safe and effective management tool in the pediatric population.

Although pelvic angiography and embolization is a potentially life-saving, minimally invasive method of achieving hemorrhage control in the unstable patient, institutional limitations must be taken into account. In a review of 68 patients who underwent pelvic angiography and embolization, time to the angiography suite had a significant effect on mortality. Patients who were in the angiography suite within 60 minutes had a mortality rate of 16%. Mortality rose to 64% if it took greater than 60 minutes to reach the angiography suite.²⁵

When angiography is not available, operative intervention should be considered. Packing of the pelvis for the purpose of attaining hemostasis from pelvic bleeding through a transperitoneal approach; however, should be avoided. The current trauma literature has shown that this approach is not an effective method of hemorrhage control and can actually lead to further bleeding as opening the peritoneum will release the tamponade. The funnel like opening of the pelvis also does not allow for packing to remain in place to provide a compressive hemostatic effect. Preperitoneal packing, however, allows for retroperitoneal tamponade and firm fixation of packs within the retroperitoneal space.⁷ This type of packing has been demonstrated to be an effective means of providing hemorrhage control in several studies with survival rates of over 70%. In these studies, postoperative angiographic embolization was successfully performed in 14 to 80% of patients.^{26 27}

A multidisciplinary approach is necessary when managing patients with pelvic fractures particularly in the presence of significant pelvic bleeding. Pelvic binders are the most effective way to control pelvic bleeding in the acute setting but should be considered a bridge therapy to a long-term pelvic stabilization. Pelvic angiography and embolization should be utilized when resources are not only available but also available in a timely manner. When external compression or angiography fails to control ongoing hemorrhage, operative intervention in the form of preperitoneal pelvic packing as a method of hemorrhage control is the next viable option. External fixation can be considered as an additional tool as both an acute and long-term treatment modality in these situations. Even after successful packing and/or external fixation is performed, angiographic embolization should be still considered. Many patients will require multiple treatment modalities to obtain adequate hemostasis, therefore, angiography/embolization, external fixation, and operative packing should not be considered exclusive of each other, but rather as overlapping treatment strategies that complement each other.

Rectal Trauma

Injuries to the rectum are a serious problem that can complicate both the short- and long-term management of traumatically injured patients. Rectal trauma, with associated pelvic fractures is rare. In a review of 1,545 patients, only 0.9% were found to have an associated rectal injury and the rate of rectal injury did not appear to increase with increasing severity of the pelvic injuries.²⁸

The rectum begins at the level of the sacral promontory and extends to the anorectal ring. It has both an intra- and extraperitoneal component. The peritoneum covers the anterior and lateral aspect of the upper one-third of the rectum. Only the anterior part of the middle third of the rectum is covered by peritoneum and the distal third of the rectum is completely extraperitoneal.⁸ Presentation and management of these injuries varies based on whether or not the injury is intra- or extraperitoneal.

Patients with intraperitoneal rectal injuries present similarly to those with colonic injuries. The majority of these patients will have signs of peritonitis or imaging studies demonstrating pneumoperitoneum and/or free pelvic fluid. Extraperitoneal rectal injuries on the contrary require a higher index of suspicion. These patients are not present with peritoneal signs. Blood on digital rectal examination and or mechanism (such as penetrating injuries to the buttocks) should elicit suspicion. CT scan with rectal contrast can be considered in selected cases with gluteal penetrating injuries.^{29 30 31}

Evolution of treatment for rectal trauma can largely be attributed to experiences with wartime injuries. Rectal injury associated mortality rate of 67% during World War I decreased to rate of 5.4% in World War II when fecal diversion with colostomy and presacral drainage became routine.^{32 33} However, this approach has recently been challenged, and current practices have moved away from the previous surgical tenets. A number of studies have demonstrated, for instance, a lack of benefit to presacral drainage or of rigorous wash out with regards to postoperative infectious complications.^{34 35 36 37} Intraperitoneal rectal injuries are now managed similar to colonic injuries. Intraperitoneal rectal or colonic injuries involving less than 50% of the circumference of the bowl can be repaired primarily. Injuries that involve greater than 50% of the rectal wall can undergo segmental resection with primary anastomosis. Neither approach mandates a diverting colostomy. Extraperitoneal injuries, those injuries that occur distal to the peritoneal reflection, are managed with fecal diversion without the need for repair of the injury in the majority of cases.^{24 38 39} Patients with rectal injuries should be appropriately resuscitated and then taken for emergent celiotomy by a general surgeon.

Rectal injuries in the pediatric population are not common. When they do occur, they are typically associated with pelvic or urinary tract injuries. Less frequently, they are associated with penetrating injuries. Three retrospective reviews identified a total of 23 children with rectal injuries. In two of the reviews, all patients underwent primary repair with colostomy for fecal diversion.^{40 41} The most recent retrospective review of nine patients, none of the patients underwent presacral drainage, three patients underwent rectal irrigation, and five patients underwent primary repair with colostomy for fecal diversion.⁴² Although there are no comparative studies in the pediatric literature regarding the need for fecal diversion, current practice and ample evidence from the adult trauma literature dictates that primary repair of the upper two-thirds of the rectum can be achieved without a colostomy.

In the setting of an acute bowel injury, antibiotic prophylaxis should be given before making any surgical incision. The antibiotic regimen should cover both aerobes and anaerobes. If adequate coverage is provided, monotherapy has been shown to be as effective as combination therapy. In one study comparing cefoperazone alone to ceftriaxone/metronidazole, and metronidazole/gentamicin/ ampicillin combinations, there was no significant difference in outcomes.^{43 44} Even in the setting of major risk factors for abdominal sepsis including gross contamination from intestinal injury, multiple blood transfusions, or high abdominal trauma index, 24-hour antibiotic prophylaxis has been demonstrated to be just as effective as a longer antimicrobial course of up to 3 to 5 days.⁴⁵

Bladder/Urethral Trauma

Bladder injuries associated with pelvic trauma in children has an incidence of 3 to 15%.^{3 9 46} An estimated 80 to 90% of patients with bladder injury have associated pelvic fractures.^{47 48 49} More than 95% of patients with a bladder injury present with gross hematuria.⁵⁰ Retrograde cystography is considered the standard imaging study for diagnosis.⁵¹ In the adult population, approximately 55% of bladder injuries are extraperitoneal and 38 to 40% are intraperitoneal. The opposite is true in the pediatric population where the majority of bladder injuries are intraperitoneal. Overall, however, the incidence of bladder injury is much lower in the pediatric population.⁴⁹ Acute management of bladder injury is contingent upon whether or not the injury is extraperitoneal or intraperitoneal.

Intraperitoneal bladder rupture requires immediate operative repair with a double layer bladder closure and placement of an indwelling bladder catheter for at least 7 to 10 days. The standard approach to management of extraperitoneal injury on the contrary is nonoperative.^{46 49 52 53} For extraperitoneal injuries, the mainstay of treatment is bladder decompression with an indwelling urinary catheter. The catheters should remain in place for 10 to 14 days. Before removal, a cystogram is obtained in order to confirm resolution of extravasation before removal. If extravasation persists, the indwelling catheter should be left in place for another 7 to 10 days and the contrast study repeated at the end of that time frame.^{52 53}

Traumatic urethral injuries are rare but can be fraught with short- and long-term complications if not identified and treated early. Overall, the incidence of traumatic urethral injuries in children is about 4% and it is about twice as common in males as it is in females. The two more common mechanisms of injury are straddle injuries and pelvic fractures. As opposed to male patients, straddle injuries are less common in females; namely because of a short urethra and its location behind the pubis.

The male urethra is divided into anterior and posterior segments where the urogenital diaphragm divides the two. The anterior urethra consists of the bulbar and penile urethra while the posterior segment consists of the membranous and prostatic urethra. Injuries to the anterior urethra primarily occur from blunt trauma such as straddle injuries. The most common site of injury because of this mechanism is to the bulbar urethra, which is compressed against the inferior surface of the symphysis pubis on impact with another object. This type of injury predominates in boys. Posterior injuries, on the contrary, are associated more with pelvic fractures. Injuries to the posterior urethra are more common with falls and with motor vehicle collisions.

Careful attention must be paid with regard to urethral injury with any child that presents with a pelvic injury, straddle injury, or penetrating injury in the vicinity of the urethra. Fresh blood at the meatus or hematuria proceeded by perineal, scrotal, or labial hematoma are the most common clinical features of urethral injury. In boys, an inability to urinate in the face of a full bladder, a high riding prostate on rectal examination or acute scrotal enlargement warrants a work-up for a urethral injury. In females, complex pelvic fractures or labial edema may signify a urethral injury. It has been estimated that for every 1 mm widening in pubic diastasis, risk for urethral injury increases by 10%.⁵⁴

Suspicion or concern for urethral injury demands performance of a retrograde urethrogram. Blind insertion of urinary catheter should not be attempted until a negative retrograde urethrogram has been obtained secondary to the risk of converting an incomplete injury to a complete disruption of the urethra with blind placement. Incomplete injuries to the anterior urethra can be managed with transurethral catheter placement using cystoscopy or with suprapubic diversion utilizing a percutaneous technique.^{46 55} The urinary catheter should be maintained for a minimum of 7 to 10 days followed by pericatheter urethrogram to confirm adequate healing before catheter removal.⁴⁹ Complete anterior urethral disruption should be managed with suprapubic urinary diversion with plans for elective surgical repair after 3 months. Posterior urethral injuries have traditionally been managed with urinary diversion with suprapubic cystostomy with delayed elective surgical repair after 3 to 6 months from the time of injury. Recently, catheter realignment has been employed with good outcomes as well.^{46 55 56} Regardless of type and location of injury, evaluation and management by a urologist is necessary.

In conclusion, in the pediatric population, only a very small percentage of patients with blunt trauma have associated pelvic injuries. When present, clinicians must be cognizant of potential associated rectal and genitourinary injuries. Although mortality in patients with pelvic injuries are typically because of the associated injuries, pelvic trauma does have the potential to be life threatening and necessitates a multidisciplinary approach to achieve favorable short- and long-term outcomes.