Genitourinary Trauma

Michael Coburn

Genitourinary injury occurs in 2–5% of all trauma patients and in at least 10% of patients with abdominal trauma, emphasizing the need for a close collaboration between the general and urologic trauma surgeon. This unique relationship that the urologist and general trauma surgeon share in the management of urologic injuries requires that common philosophies of management be applied.

Controversies exist in the approach to urologic trauma, and recent efforts to achieve a broad consensus in the management of diverse urologic injuries have resulted in numerous publications. One such effort, sponsored by the World Health Organization and the Societe Internationale d’Urologie, involved a 25-year review of world literature focusing on levels of evidence and development of evidence-based management recommendations.^1–5 Another similar effort through the European Association of Urology (EAU) had a similar focus.⁶ Both produced useful syntheses of a large body of literature. The current discussion will offer a broadly applicable approach to the management of urologic trauma based on current literature and local experience and perspective.

ANATOMY

Beginning with surgical exposure for upper tract injuries, the contemporary approach to the injured kidney is through an anterior midline abdominal incision. Access to the kidneys and ureters is generally obtained by reflecting the colon on either side medially and exposing Gerota’s fascial envelope. While modern descriptions of exposing the injured kidney often involve a discussion of first obtaining vascular control of the renal vessels prior to entering the perirenal hematoma, the important element in this practice is achieving access to the pedicle such that atraumatic vascular clamping can be achieved if significant bleeding is encountered. This can be accomplished through individually dissecting and “looping” the renal vessels through an incision in the posterior peritoneum over the aorta (which can allow access to either the left- or right-sided artery and the left-sided vein) or by first reflecting the colon on the side of injury and then obtaining vascular control or access to the pedicle. Obviously, the renal vessels should be approached first and dissected directly when there is suspicion of a renovascular injury (medial or perihilar hematoma, pulsatile hematoma). When suspicion of a renovascular injury is low, many urologic trauma surgeons successfully approach the kidney by first reflecting the colon and then achieving vascular control. This is achieved by individually dissecting the vessels, by using a vascular pedicle clamp, or through digital compression.

The kidney is located high and posteriorly in the retroperitoneum. The midline incision may need to be extended to the xiphoid process and additional upper abdominal retraction inserted for proper exposure. The kidney overlies the diaphragm, transversus abdominis aponeurosis, and quadratus lumborum muscle laterally and psoas major muscle medially. Significant bleeding from these muscles and the deep muscles of the back can occur following penetrating trauma and may confuse the picture in which brisk bleeding is occurring in the renal fossa. The kidney is enclosed in a thin but strong fibrous capsule, which should be left intact during renal dissection and mobilization. As the capsule is usually lifted off the parenchyma by an underlying hematoma, the entire capsule may inadvertently be stripped off the kidney by the sweeping finger used to quickly elevate the kidney into the wound. Ideally, the kidney should be mobilized through sharp and blunt dissection working from a normal area toward the area of parenchymal injury to keep the capsule on the kidney. Stripping the capsule complicates the repair of the kidney and should be avoided.

Recognizing patterns of injury is important, and the trauma surgeon should anticipate injuries to adjacent organs based on the relational anatomy of the kidney and ureter and the trajectory of a penetrating injury⁷ (Fig. 36-1). The left kidney is crossed anteriorly in its upper portion by the tail of the pancreas and lies behind the lower portion of the spleen. On the right, the duodenum is immediately anterior to the hilar region. In the setting of a renal injury on the right side, the right colon, liver, and duodenum are commonly injured in penetrating trauma. With blunt trauma, an associated hepatic laceration is most common. On the left side, injuries to the left colon, stomach, spleen, and pancreas are common in penetrating trauma. And lacerations of the spleen are particularly common with blunt trauma to the left upper quadrant. Injuries to the diaphragm are also common with penetrating renal injury and less common with blunt injury. The left adrenal gland is located medial to the upper pole of the left kidney, while the right adrenal gland is located in a more cephalad position relative to the right upper renal pole and may be in a retrocaval position.

FIGURE 36-1 Renal anatomy: relational anatomy of the kidney. Note proximity of great vessels, duodenum, liver, spleen, pancreas, and colon, relevant to predicting patterns of injury and likely sites of concomitant organ injury in renal trauma.

At the level of the renal pedicle, there are most commonly single renal arteries and veins present bilaterally. The renal vein, artery, and renal pelvis are organized in an anterior-to-posterior orientation. On the right side, the gonadal vein arises from the vena cava at or slightly below the level of the renal pedicle. A lumbar vein, which may be quite large, often arises from the posterior aspect of the right renal vein, near the insertion with the inferior vena cava. The right adrenal vein enters directly into the vena cava, often on its posterolateral aspect. On the left, the main branches of the renal vein include the left gonadal, the adrenal, and one or more lumbar veins. This asymmetry of the collateral branches of the renal veins explains why the left renal vein can be safely ligated near the vena cava, with an 85% chance of renal preservation. In contrast, the right kidney will most likely develop venous thrombosis and become nonviable if the right renal vein is ligated.

For the urologic trauma surgeon who engages in intrarenal surgery and renal reconstruction, knowledge of the intrarenal anatomy is important (Fig. 36-2). The renal arterial supply consists of the following five segments: apical, superior (anterosuperior), middle (anteroinferior), lower (inferior), and posterior. The posterior branch crosses cephalad to the renal pelvis to reach its segment. About 25% of kidneys receive accessory arterial branches directly from the aorta. These may enter through the renal sinus or at the upper or lower poles. Certain anomalies of the upper urinary tract, such as horseshoe kidney and congenital obstructive and duplication types, must be familiar to the trauma surgeon, as they may impact management.

FIGURE 36-2 Intrarenal vascular anatomy: vascular branches supplying various arterial segments of the renal parenchyma. Knowledge of intrarenal anatomy is critical to successful reconstructive efforts.

The blood supply to the ureter is particularly important in surgery for urologic trauma (Figs. 36-3 and 36-4). The main sources are the renal artery from above, the aorta or common iliac arteries, and the vesical arteries from below. Branches approach the upper and midureter primarily from the medial side, while in the lower pelvis, the blood supply to the ureter enters primarily from a lateral direction. These branches form a long, predictable anastomotic chain usually with a single longitudinal vessel that runs the length of the ureter, in the plane between the ureteral adventia and muscularis.

FIGURE 36-3 The ureteral blood supply originates from branches of the adrenal and renal arteries in the upper third, branches of the aorta and gonadal arteries in the middle third, and the pelvic vessels as shown in the lower third. Knowledge of the ureteral blood supply and derangements due to preexisting pathology or prior surgery is important in maintaining ureteral viability during surgical mobilization and reconstruction.

FIGURE 36-4 Ureteral anatomy: the longitudinal blood vessels run deep to the adventitial sheath; it is important to achieve a dissection plane superficial to this layer to avoid devascularization of the ureter during surgical mobilization.

Anatomy of the urethra, perineum, and external genitalia may be less familiar to the general trauma surgeon. The gross anatomy and fascial layers of the genitalia and perineum are important in trauma, as they largely determine the manner in which blood and urine extravasate following urethral or genital trauma (Fig. 36-5).

FIGURE 36-5 Diagram of sites of extravasation, associated with urethral disruption. (A) With an intact Buck’s fascia, extravasation of blood and/or urine is isolated to the penile shaft. (B) With Buck’s facial defect, extravasation extends into the scrotal tissues and compartments.

INJURY GRADING AND SCORING SYSTEMS FOR GENITOURINARY INJURIES

The American Association for the Surgery of Trauma (AAST) Injury Scaling Committee has devised a staging system for urologic injuries. The system, originally published in 1989 and since amended, addresses injuries to the kidney, ureter, bladder, urethra, testis, scrotum, and penis (Table 36-1).⁸ For some organs such as the kidney, the system has proven highly applicable and has come into common use. For other organs, such as bladder and ureter, the AAST system has been less commonly utilized for a variety of reasons, largely relating to lack of specificity of available imaging approaches to provide the necessary data for assignment of a grade. The grading systems for urethra and external genitalia are coming into more common use and are of value in addressing outcomes following such injuries. Several aspects of the staging system have received attention regarding their clinical significance and impact on decision making, complication rates, and patient outcomes.^9–11

TABLE 36-1 Urologic Injury Scale of the American Association for the Surgery of Trauma

As noted, the renal Organ Injury Scale utilizes five grades of injury, ranging from contusion or subcapsular hematoma (I) to shattered kidney or avulsion of the hilum (V) (Fig. 36-6). It is valuable to specifically distinguish the parenchymal lacerations from renovascular trauma in the group IV and V injuries when reporting experience, as management and outcomes differ between these entities. The varying degrees of renal injury as described in the scaling system are depicted diagrammatically in Fig. 36-6. Recent data have shown support for the clinical utility and validity of the renal injury scale, indicating that this system is predictive of morbidity in blunt and penetrating renal injury, of mortality in blunt injury,¹⁰ and of the risk of nephrectomy with exploration for renal trauma.

FIGURE 36-6 Organ injury scaling system for renal trauma.

As the percentage of the circumference of the ureter that has been disrupted is difficult to determine from imaging studies, the ureteral scaling system is mainly amenable to the operative setting. For the bladder, the distinction of intraperitoneal from extraperitoneal rupture is important and is addressed in the scaling system, but whether the length of the laceration in the bladder wall truly has clinical significance has not been demonstrated. For urethral injuries, the scaling system addresses anatomic factors that can often be determined from retrograde urethrography (RUG) and provide advantages over the earlier system described by Calopinto and McCallum.¹² The current AAST system addresses urethral disruption based on whether the injury is complete or incomplete (i.e., whether contrast enters the bladder) and on the length of the urethral defect and presence of extension into prostate or vagina. Endoscopic assessment indicates that in some cases where the retrograde urethrogram would suggest a complete disruption, partial circumference continuity does exist, at times allowing for insertion of a catheter into the bladder. Nevertheless, despite some lack of specificity, the AAST organ injury scaling system has substantial usefulness.

The scaling system for organ-specific injuries as applied to genitourinary trauma (Tables 19-22 and 29-31 from AAST Web site) has introduced a needed advance in the field.⁸ The designations of the AAST system should be utilized whenever possible in clinical descriptions and published work on urologic trauma.

CLINICAL PRESENTATION AND DIAGNOSIS OF RENAL TRAUMA

Incidence and Patterns of Injury

Renal injuries occur in approximately 1–3% of all trauma patients and up to 10% of patients with abdominal trauma. The percentage of blunt and penetrating trauma varies dramatically depending on the health care institution and the population served. In some urban trauma centers, penetrating injuries predominate,^7,13–15 although overall, approximately 90% of significant renal injuries are due to blunt trauma in the United States.¹⁶

For penetrating trauma, nearly all renal gunshot wounds are associated with injuries to other intra-abdominal organs; for renal stab wounds, approximately 60% of cases occur in combination with another intra-abdominal injury.

Kidneys with preexisting anatomic abnormalities appear to be more vulnerable to significant injury from seemingly minor blunt trauma.^17,18 Such entities would include obstruction of the ureteropelvic junction, large cystic lesions, and renal neoplasms. Injuries to nonurologic structures in the abdomen are found in approximately 20–33% of patients with blunt renal injuries.

Clinical Presentation and Evaluation

A history of a blow to the flank, deceleration trauma, fall from a height, or penetrating abdominal, pelvic, and lower chest injuries should raise the possibility of a renal injury. Hematuria is the most common sign of renal trauma, although the magnitude of the hematuria correlates poorly with the magnitude of injury.

Physical examination in patients at risk for renal injury should include careful assessment of the abdomen, back, flank, and chest, along with a complete genitourinary examination. Findings suggestive of a renal injury include tenderness in the flank, costovertebral angle or abdomen, a palpable flank mass, or ecchymosis in the flank, back, or abdomen. Complete inspection of the trunk for a penetrating injury is critical. Stab wounds posterior to the anterior axillary line carry a risk of renal injury, with only about 12% of such injuries being associated with injury to another organ.

Laboratory assessment should include urinalysis by dipstick, as well as microscopic examination for blood or infection. The first specimen in the emergency center should be analyzed for hematuria to optimize diagnostic accuracy. Determination of serum electrolytes, blood urea nitrogen (BUN) and serum creatinine, and hemoglobin is important. A blood sample for type and screen or cross-match should be obtained when clinically appropriate.

Radiographic Imaging for Renal Trauma

Traditionally, all patients with abdominal trauma and any degree of hematuria were imaged in the emergency center on presentation. Using this approach, some series of renal trauma have shown that greater than 90% of imaged patients will have only minor injuries, primarily contusions or other minor injuries not requiring intensive monitoring or intervention. With an eye toward cost-effectiveness and minimizing the time and potential morbidity of unnecessary imaging, several groups have assessed the safety and feasibility of establishing more selective approaches toward renal imaging in the trauma setting.¹⁹ The disadvantages of imaging include expense, radiation exposure, possible allergic or nephrotoxic reactions to contrast, time expenditure, and the risk of moving the patient. These factors need to be balanced against the risk of missed injuries with a resultant delay in diagnosis. In 1985, the group from San Francisco General Hospital analyzed their renal trauma experience and found that the only findings that were predictive of significant renal injury were the presence of penetrating trauma, or blunt trauma with gross hematuria or with microhematuria and shock. Shock was defined as a systolic blood pressure <90 mm Hg at any time postinjury, including during transport by EMS. In a review of 812 patients with microhematuria but without shock, no significant renal injuries were detected. All 44 injuries in this original series were found among the 195 patients with gross hematuria or microhematuria and shock. This series has been extended over the years such that in the expanded patient group of 2,254 patients with renal trauma approximately one third were imaged and two thirds were not. Within this group, no major renal injuries were missed using the established criteria.^20–22

Other investigators have modified these imaging criteria according to their own experience and judgment. Some have suggested including standard imaging for patients with injury to the brain, loss of consciousness, or altered mental status, with the belief that the loss of information on a physical examination and the magnitude of trauma in such patients may create a higher risk of a missed injury. Some have suggested extending imaging indications to patients with mechanisms of injury consistent with deceleration trauma. This approach avoids missing injuries to the renal pedicle (e.g., intimal disruption in the renal artery and renal devascularization), which may present with no hematuria in 20–33% of patients. The presence of fractures of long bones, fractures of the lower ribs, or fractures of transverse spinous processes has also been suggested as an indication to modify the previous imaging restrictions, possibly predicting a higher risk of occult renal injury. In the pediatric population (addressed in Section “Pediatric Renal Trauma”), imaging for patients with only microhematuria has been more liberally utilized.

As noted, the criteria involving limiting imaging to patients with gross hematuria or microhematuria with shock have not been extended to those with penetrating trauma. Patients with penetrating trauma with any degree of hematuria, injury proximity, or suspicion are appropriate candidates for imaging of the urinary tract, regardless of the presence or magnitude of hematuria. Significant penetrating injuries can present without hematuria, particularly if trauma to the major collecting system causes all urine from the injured kidney to exit into the retroperitoneum, preventing ureteral peristalsis.

In penetrating trauma, imaging would generally be obtained in assessing a patient’s candidacy for nonoperative management in the appropriate clinical setting. The concept of obtaining preoperative renal imaging simply to demonstrate the presence of two functioning renal units prior to surgical intervention has become less popular in recent years. Instead, careful intraoperative palpation of the kidneys and, on occasion, intraoperative intravenous pyelogram (IVP) may be used selectively during a trauma laparotomy to demonstrate renal presence or function.²³ The selection of imaging modalities has evolved greatly since the advent and availability of computed tomography (CT) scanning to emergency center evaluation.¹⁹ While the bolus IVP with nephrotomography had in the past been the standard imaging approach, the CT scan has, over the years, become the gold standard for precise staging of renal injuries (Fig. 36-7), and has largely replaced intravenous pyelography in most clinical settings.

FIGURE 36-7 Staging computed tomography scans for blunt renal injury. (A) Grade II injury: blunt trauma, small right posterior subcapsular and perirenal hematoma without obvious parenchymal laceration. (B) Grade II and III injury: blunt trauma, laceration posteromedially in left kidney without collecting system injury. (C) Grade IV parenchymal injury: blunt trauma, deeper laceration to right kidney, full-thickness parenchymal laceration with collecting system injury as indicated by contrast extravasation. Moderate-sized perinephric hematoma. No significant devitalized parenchyma noted.

Although the IVP had in the past been described as being accurate for clinical staging purposes in 60–85% of patients, CT scanning offers a number of important advantages.²⁴ Nevertheless, trauma surgeons and urologists should remain familiar with the findings suggestive of renal injury on IVP, as routine use of CT for trauma assessment is not consistently available, especially when considering variations in international practice and infrastructure, and intraoperative IVPs may still be necessary at times. These IVP findings include the presence of a fracture of a transverse process on the scout film, presence of a mass effect in soft tissue, loss of the psoas margin on the involved side, and alteration of the longitudinal axis or vertical displacement of the kidney. Loss of a clear renal cortical outline, gross extravasation of contrast, ipsilateral decrease in renal excretory function, and loss of opacification of portions of the collecting system should all be noted. The IVP allows confirmation of the presence of two renal units, gives general information of the extent of injury, and may show significant extravasation.

Estimates of the accuracy of IVP in detection of renal injury vary. In general, the IVP should be viewed as a crude means of detection, rather than as a means to obtain precise staging. Some studies indicate that as many as 20% of patients with significant renal injuries may have a normal IVP. In addition, up to half of patients with reduced function or nonfunction of a kidney on IVP will have a reason for it other than arterial occlusion, including contusion, overhydration, and hypotension or hypoperfusion.

Advantages of CT over IVP include identification of contusion and subcapsular hematoma, definition of the location and depth of parenchymal lacerations, more reliable demonstration of extravasation of contrast, and identification of injuries to the pedicle and artery (“rim sign,” “cutoff sign,” etc.). There is also enhanced imaging of the perinephric space, other solid viscera (liver, spleen, pancreas), as well as delineation of many cases of perforation of a hollow viscus and identification of free intraperitoneal fluid. For these and other reasons, the contrast-enhanced CT scan has largely replaced the IVP for trauma imaging. With the current spiral CT scanners, sequences are so rapid that it is important to be sure that delayed, excretory images are obtained to avoid missing extravasation from the collecting system or ureter, which may not be apparent from early images alone.²⁵

Arteriography has had less of a role in the staging of a renal injury since CT has become popular, especially considering its cost, invasiveness, and the special expertise required. As the use of CT for diagnosis of a pedicle injury has become standard, far fewer arteriograms are being obtained. Still, precise delineation of arterial anatomy and interventions for control of hemorrhage mandate the continued use of renal arteriography on a selective basis (Fig. 36-8). In Europe and other parts of the world, abdominal ultrasound has been extensively utilized in diagnosing and assessing blunt renal injury. In the United States and elsewhere the Focused Assessment for the Sonographic Evaluation of the Trauma Patient (FAST) study is performed to assess for free intraabdominal fluid rather than for the delineation of an injury to parenchyma of solid organs. The ability to apply high-resolution Doppler techniques to assess renal perfusion and vascular anatomy may extend the use of ultrasound for renal imaging in the future.

FIGURE 36-8 (A and B) Renal artery occlusion due to intimal disruption following deceleration injury. Restrained driver in head-on motor vehicle collision. The left kidney is nonperfused and demonstrates minimal renal sinus vascular enhancement and cortical rim enhancement from capsular vessels. This finding is considered pathognomonic for this injury and does not require arteriographic confirmation unless the vascular surgeon believes further vascular imaging is necessary to plan therapy.

Retrograde pyelography plays a limited role in clearly defining anatomy of the ureter and collecting system when a pattern of medial extravasation or failure of ureteral opacification on CT or IVP is present.

PEDIATRIC RENAL TRAUMA

Some studies suggest that the pediatric kidney is more vulnerable to trauma than is the adult kidney.²⁶ Reasons for this include the relatively larger size of the kidneys compared with the adult, the relative deficiency of perinephric fat in the child, and, probably, the higher incidence of preexisting renal abnormalities. One recent review found that 8.3% of pediatric renal injuries occurred in the setting of preexisting renal abnormality,¹⁷ with other estimates of preexisting renal abnormality described in as many as 23% of major pediatric renal injuries due to blunt trauma. Some data suggest that the kidney is the most commonly injured intra-abdominal organ in children.

It is nearly universally agreed that the presence of gross hematuria after trauma in the pediatric patient deserves further investigation with imaging of the urinary tract. As in the adult, the CT scan has the major role in staging such injuries for the same reasons as described earlier. Several studies suggest that only about 5% of pediatric patients with major renal injuries will develop signs of shock, further emphasizing the importance of an aggressive diagnostic approach. Pediatric patients can maintain a normal blood pressure despite significant blood loss, and persistent tachycardia is a particularly important parameter to note in the pediatric patient as a potential sign of significant blood loss.

The currently accepted approach in the adult is not applied liberally in the pediatric setting. Many authors suggest that all pediatric patients with any degree of hematuria after significant trauma should undergo renal imaging, while some have suggested modified criteria. One study has suggested that microscopic hematuria with greater than 50 red blood cells per high-power field in the pediatric setting should be considered an imaging criterion, regardless of hemodynamic parameters.²⁷

Certain types of renal injuries are clearly more common in the pediatric patient. These include laceration of the renal pelvis, avulsion of the ureteropelvic junction, and forniceal avulsion. When extensive medial extravasation is noted and/or the ureter does not opacify with contrast despite adequate excretion into the renal collecting system, a disruption of the major collecting system should be considered. In such cases, retrograde pyelography may be necessary to clarify the anatomy and achieve a diagnosis.

As in the adult, the use of the rapid spiral CT scanner can lead to a pitfall in diagnosis if a delayed sequence is not requested. Limiting the study to a nephrographic or early excretory phase may fail to demonstrate extravasation or asymmetrical opacification of the ureters, which would be readily visible on later images.

Overall, approximately 85% of pediatric renal injuries from blunt trauma are minor (contusions, superficial parenchymal lacerations) and are managed with bed rest and observation. Pedicle injuries comprise about 5% while major parenchymal injuries occur in 10–15% of patients. As in the adult, it is these latter groups for which management is somewhat controversial; however, it is largely agreed among pediatric urologists that operative decisions are based mainly on hemodynamic status rather than imaging criteria. The potential for successful management of kidneys that look very severely injured on imaging studies is remarkable in the pediatric population, and a nonoperative approach is the norm. Surgical treatment is generally reserved for patients with ongoing bleeding or hemodynamic instability, for those who have clearly failed an attempt at nonoperative management, and for penetrating injuries.²⁸

CLINICAL PRESENTATION AND DIAGNOSIS OF TRAUMA TO THE URETER, BLADDER, URETHRA, AND EXTERNAL GENITALIA

Ureter

Ureteral injuries are relatively uncommon, occurring in approximately 4% of patients with penetrating abdominal injuries and in less than 1% of those with blunt abdominal trauma. Concomitant visceral injury occurs in the majority of patients with ureteral injuries from penetrating trauma. While hematuria is an important sign of ureteral injury, it may be absent 15–45% of the time. As such, a high index of suspicion for ureteral injury is critical.^29–32 In fact, ureteral injury is one of the most common sites of missed injury at laparotomy, with one recent report noting a missed injury rate of 11% (15). While direct visualization of the ureter is the mainstay of detection of ureteral injury at the time of laparotomy, imaging modalities useful for detection of ureteral trauma include an IVP and contrast-enhanced CT scanning.¹⁶ Modern spiral scanners move rapidly through the abdomen following administration of contrast, and, unless a delayed excretory phase is specifically requested, extravasation may be missed as previously described. Failure of the distal ureter to opacify on a CT scan should raise concern of an injury.^33–35 When noninvasive imaging fails to provide sufficient detail regarding ureteral anatomy or the specific nature of an injury, cystoscopy with retrograde pyelography may be indicated.

Bladder

Sudden compression of the full bladder, shear forces, or a pelvic fracture may result in a blunt rupture. Rupture may be accompanied by lower abdominal pain, by an inability to void, and by suprapubic or perineal ecchymoses. The cardinal sign of injury to the bladder is gross hematuria, present in greater than 95% of cases, while only about 5% of patients will have microscopic hematuria alone.³⁶ Over 80% of patients with a bladder rupture have an associated pelvic fracture in centers with a high percentage of blunt trauma. An association of bladder rupture with disruption of the posterior urethra, also in the setting of pelvic fracture, may occur in 10–20% of patients.^37,38 Overall, recent data indicate that genitourinary injury occurs in approximately 15% of pelvic fractures in the pediatric setting¹⁷ and that the incidence of injury to a pelvic organ is fairly comparable between adult and pediatric patients.^39,40

Stress cystography is the standard study for diagnosis of injury to the bladder (Fig. 36-9).⁴¹ It is important that the bladder be adequately filled to avoid false-negative studies. For the adult bladder, the standard volume of filling is 300–400 mL of iodinated contrast (30% iodine commonly utilized), which is infused through the indwelling Foley catheter by gravity. Alternatively, the bladder can be filled by gravity to a point at which the patient describes a sense of bladder fullness. If the patient is obtunded or unable to indicate that there is a sense of fullness, using a standard filling volume is a useful methodology. A filling film is obtained that should be a vertically oriented abdominal image designed to show the entire abdomen. Patterns of contrast extravasation have been described for intraperitoneal, extraperitoneal, and combined ruptures (Fig. 36-10). Hematuria of bladder origin without contrast extravasation on a properly performed stress cystogram is consistent with a contusion or minimal mucosal injury, which is uniformly managed nonoperatively. Postdrainage washout films are generally recommended to avoid false-negative cystograms in which extravasated contrast may be missed if located only anterior or posterior to the distended bladder on an anteroposterior film.

FIGURE 36-9 (A and B) Stress cystogram: through Foley catheter, the bladder is filled by gravity to a standard volume (300–400 mL typically in adult), or to the point of perceived fullness by patient. Plain radiograph obtained to allow visualization of upper and lower abdomen, followed by washout film.

FIGURE 36-10 Bladder: stress cystograms for assessment of suspected bladder injury following blunt trauma to pelvis. (A) Stress cystogram in patient with gross hematuria and pelvic fracture, demonstrating adequate bladder filling and typical pattern of extraperitoneal extravasation—flame-shaped contrast density lateral to right lower bladder segment. Injury managed successfully with 10 days of catheter drainage. (B) Washout phase following stress cystogram. Extraperitoneal extravasation pattern noted in right hemipelvis. Washout films may reveal extravasated contrast anterior or posterior to the contrast-filled bladder, which can be missed on films obtained when the bladder is filled with contrast. (C) Lateral compression of bladder from pelvic hematoma, along with extraperitoneal extravasation pattern in right pelvis, on an incomplete washout film. (D) Intraperitoneal bladder rupture. Note extravasated contrast outlining colic gutters, surrounding loops of small bowel, and occupying cul-de-sac in pelvis, indicative of intraperitoneal contrast. (E) Intraperitoneal bladder rupture. Again, note contrast in pelvis and outlining of right colon and small bowel in pelvis. Cystograms following penetrating pelvic trauma with hematuria. (F) Gunshot wound to pelvis in patient with microscopic hematuria. Bladder is intact, but is displaced to right due to large, left-sided pelvic hematoma. Obturator vessel injury noted; vessels ligated following evacuation of hematoma at laparotomy and pelvic exploration. (G) Gunshot wound to bladder with intravesical clot creating filling defect in bladder. Bladder incompletely filled; extravasation noted on subsequent film, following optimal filling of bladder.

Currently, stress cystography is most commonly obtained using a CT technique (Fig. 36-11).⁴² The same general principles apply as for static cystograms (i.e., adequate bladder filling is essential to avoid missed injuries) (Fig. 36-11B and C). Studies comparing the accuracy of standard radiographic stress cystography with CT cystography suggest equivalent capability in defining and staging bladder injuries, while the CT cystogram provides enhanced information regarding the perivesical space and adjacent structures. Simply clamping a bladder catheter following intravenous contrast administration, with the expectation that passive filling with contrast-opacified urine will suffice, is not adequate and will result in an unacceptably high percentage of false-negative examinations, with either the standard radiographic or the CT technique.⁴² In selected cases, flexible cystoscopy may aid in the acute diagnosis of bladder injury.⁴³

FIGURE 36-11 (A) Computed tomography (CT) cystogram demonstrating intraperitoneal bladder rupture. A standard stress cystographic technique has been employed, with instillation of 350 mL of contrast followed by scanning of upper, middle, and lower abdomen. Contrast is seen filling colic gutters and filling the true pelvis, in this case clearly outlining the ovaries. (B) False-negative CT cystogram. This image was obtained by clamping the indwelling Foley catheter and obtaining CT images of the pelvis with passive filling of the bladder following intravenous contrast administration. No extravasation is noted, but the bladder is not adequately filled to reliably exclude injury. A properly performed static cystogram following the CT revealed extensive intraperitoneal extravasation. Inadequate bladder filling is the most common reason for a false-negative cystogram. (C) Attempted CT cystogram following pelvic fracture in a 13-year-old male. Extravasation extends through the pelvic floor into the buttock, and no filling of the bladder is seen. The Foley balloon is actually positioned in the pelvic hematoma. The patient was found to have a bladder neck avulsion injury, which was initially managed with an open surgical cystostomy, and then surgically reconstructed 72 hours following injury.

Urethra

Trauma to the anterior urethra may result from straddle injuries with sudden compression at the level of the midurethra to deep bulbar urethra against the inferior pubic arch. Urethral distraction injuries, or posterior urethral disruption, may accompany pelvic fracture in 4% to >10% of patients. Bilateral fractures of the pubic rami, especially when accompanied by an open pelvic ring (abnormally distracted sacroiliac joint), may be present in patients who have suffered posterior urethral disruption as well. The classification system used to further describe urethral trauma is discussed in Section “Injury Grading and Scoring Systems for Genitourinary Injuries.” It is important to determine from the urethrogram if an injury is partial (contrast passes proximal to the point of extravasation filling the more proximal urethra or bladder) or complete (all contrast extravasates, and none enters the urethra proximal to injury or bladder), as this factor has an impact on selection of management.⁴⁴

Blood appearing at the urethral meatus, inability to void, presence of a perineal hematoma, and inability to clearly palpate the prostate on rectal examination should make one suspicious of urethral injury (Fig. 36-12). When urethral injury is suspected, a retrograde urethrogram should be performed (Fig. 36-13). Approximately 30 mL of iodinated contrast is instilled via a catheter inserted just within the urethral meatus, at which point a plain radiograph is obtained. A normal retrograde urethrogram should demonstrate contrast filling an intact urethra and entering the bladder without extravasation. No attempt at insertion of a bladder catheter should be pursued until a negative retrograde urethrogram is obtained to avoid further complicating a urethral rupture (Fig. 36-14).

FIGURE 36-12 Mechanism of anterior urethral disruption due to straddle injury; extravasation pattern and hematoma limited in this case by Colles’ fascia, due to rupture of Buck’s fascia along with full thickness of urethral wall. Hematoma and urinoma may extend along shaft of penis and into scrotum and perineum.

FIGURE 36-13 Technique of retrograde urethrogram. Retrograde urethrogram: catheter is inserted into urethral meatus, with minimal balloon inflation to maintain position and allow hands to be out of x-ray field. Contrast is instilled to distend urethra.

FIGURE 36-14 Urethra: posterior urethral disruption with pelvic fracture. (A) Retrograde urethrogram demonstrates extravasation of contrast both above and below urogenital diaphragm and no filling of prostatic urethra or bladder neck, consistent with complete disruption. Note pubic ramus fracture and marked cephalad elevation of bladder (bladder filling with contrast excreted following intravenous administration for computed tomography scan). Hemodynamically unstable patient required angiographic embolization for pelvic hemorrhage. Urethral disruption managed with open suprapubic cystostomy. (B) Combined antegrade and retrograde contrast studies 6 months postinjury, demonstrating obliterated posterior urethral distraction defect, in preparation for reconstructive surgery.

Following placement of either a urethral catheter (if the urethra proved normal or by a urologist using direct vision techniques in selected incomplete injuries) or a suprapubic catheter (if urethral disruption was revealed), a stress cystogram should still be performed if hematuria is present. This is because 10–15% of patients with urethral disruptions from a pelvic fracture will have a concomitant injury to the bladder.

External Genitalia

Genital injuries represent a diverse group of traumatic events.⁴⁵ These include the classic blunt penile fracture (which occurs from forceful bending of the erect penis, often during intercourse), crush injuries with rupture of the testis, penetrating injuries, and industrial accidents. Amputation injuries of the penis or testicle can occur due to assaults, self-mutilation, or industrial trauma. After major blunt trauma to the scrotum, the risk of testicular rupture is approximately 50%. An ultrasound examination of the scrotum may be valuable to distinguish testicular rupture from a hematoma of the scrotal wall or hematocele (blood within the tunica vaginalis compartment).

NONOPERATIVE MANAGEMENT OF GENITOURINARY INJURIES

While nonoperative management for many urologic injuries has become well established, the selection of operative versus nonoperative management for certain genitourinary injuries remains controversial. Recent reviews of urologic management based on careful assessment of levels of evidence reveal a notable paucity of level 1, prospective management studies.^1–6 The relatively recent efforts to accurately and uniformly describe and stage the nature of injuries and the lack of long-term follow-up leave many questions as to the best way to manage many forms of genitourinary trauma.

Kidney

It has long been accepted that low-grade renal injuries can be managed nonoperatively with a high success rate. Renal contusion and subcapsular hematomas are routinely managed expectantly and only rarely would surgical or other interventions be required in such cases. These injuries heal spontaneously with few exceptions as do low-grade parenchymal lacerations. Depending on the institutional bias and experience, some urologic trauma surgeons may limit operative management of renal injuries to those in which the patient is hemodynamically unstable, almost regardless of imaging findings. Alternatively, others would include those injuries in which the grade of injury is high, presumably translating into a higher incidence of postinjury complications with nonoperative management. A number of indications for renal exploration following injury have been suggested by McAninch and Carroll.⁴⁶ These include hemodynamic instability, ongoing hemorrhage requiring significant transfusion, pulsatile or expanding hematoma on exploration, and avulsion of the pedicle. These strong indications for surgical or other procedural intervention remain widely accepted. Relative indications for surgical intervention have included high-grade injuries, large perirenal hematoma, presence of urinary extravasation on contrast studies, significant devitalized fragments of parenchyma, and findings in the operating room during laparotomy with an incompletely staged injury. While there is lack of consensus regarding these relative surgical indications, there is a general trend toward nonoperative management in many of these situations, as long as hemodynamic stability is maintained.²⁸

Proponents of the nonoperative management approach suggest that many high-grade injuries will heal without surgery, complications can frequently be managed with nonsurgical techniques (percutaneous drainage, stenting, angiographic embolization), and renal salvage rates are better overall when renal exploration is avoided. This school of thought would maintain that, with few exceptions, it is only hemodynamic instability that should prompt surgical intervention for the injured kidney, not injury stage or other predetermined imaging criteria.

In contrast, proponents of a more aggressive surgical approach would suggest that higher grades of renal injury carry an unacceptably high complication rate and that such complications, when they occur, have a high likelihood of resulting in otherwise avoidable morbidity or nephrectomy (Fig. 36-15). Proponents would suggest that early exploration and repair offer the advantage of early debridement of devitalized tissue, definitive hemostasis, repair of injuries to the collecting system, and early institution of appropriate drainage. As such, postinjury infection, urinoma, and hemorrhage risk are minimized. The descriptions of “absolute” and “relative” indications for renal exploration for trauma have been suggested to attempt to provide assistance in this decision-making process.^46–48

FIGURE 36-15 Grade V parenchymal injury. (A) This image through the upper abdomen demonstrates the upper pole of the left kidney to be elevated by a perinephric hematoma. The upper pole is well perfused and intact. (B) A lower section reveals a large, left retroperitoneal hematoma; the right kidney is perfused and appears normal. This is an early arterial and parenchymal phase, as indicated by the degree of enhancement of the aorta and right renal cortex. (C) A more caudal image demonstrates a large, devascularized fragment of the left kidney; this represents the lower third of the kidney that has been avulsed from the perfused portion of the kidney. This injury required operative repair, which involved removal of the avulsed parenchymal fragment, suturing of the large intrarenal vascular branches that were avulsed, and reconstruction of the collecting system and the level of the junction of the lower infundibulum with the renal pelvis. While some reports suggest that some grade V injuries may be manageable nonoperatively, most clinicians consider this anatomy of injury a surgical indication. Difficulties in classifying some parenchymal injuries as grade IV versus grade V may contribute to this apparent reported variability of opinion and outcome.

For certain injuries, operative management is nearly universally accepted. These include blunt avulsion or penetrating lesions of the renovascular pedicle, AAST grade V parenchymal injuries, and ureteropelvic avulsion or complete avulsion of the fornices. While occasional case reports have suggested that grade V renal injuries can be managed nonoperatively, most studies demonstrate that 90–100% of such injuries require urgent nephrectomy.⁴⁹ In reviewing the literature on nonoperative management of grade V renal injuries, the accuracy of classification is questionable, and some reports of successful management of grade V injuries probably are actually describing grade IV parenchymal lacerations. In general, attempts at nonoperative management of true grade V renal injuries are not advised and may expose the patient to substantial risk, although there remains some controversy in this area.

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