Hematuria

The best indicators of significant urinary system injury include the presence of microscopic (>5 red blood cells/high-power field [RBCs/HPF] or positive dipstick finding) or gross hematuria and hypotension (systolic blood pressure <90 mm Hg). The presence of microscopic hematuria is often characteristic. However, gross hematuria has been observed in minor renal contusions and microscopic hematuria has been associated with severe renal injuries. For example, hematuria was absent in 7% of 420 grade IV renal injuries in a recent analysis (Shariat et al, 2008a) and 36% of renal vascular injuries from blunt trauma demonstrated no blood in the urine (Cass, 1989). Also, approximately 50% of injuries to the ureteropelvic junction have no microscopic or gross hematuria. Therefore the degree of hematuria and the severity of the renal injury do not consistently correlate. In patients with blunt trauma, if shock is noted with microscopic hematuria, the incidence of significant renal injuries increases (Mee et al, 1989; Miller and McAninch, 1995; Nicolaisen et al, 1985). In addition, hematuria has been used as a general predictor of nonrenal intra-abdominal organ injury after blunt trauma (Knudson et al, 1992).

The authors use the first aliquot of urine obtained either by catheterization or by voiding to determine the presence of hematuria. Later urine samples are often diluted by diuresis from resuscitation fluids, resulting in an underestimation or absence of hematuria. Any degree of visible blood in the urine is regarded as gross hematuria. Microscopic hematuria can be detected by dipstick analysis or microanalysis. The dipstick method is rapid and has a sensitivity and specificity for detection of microhematuria of more than 97%, even though a poor correlation with actual urinalysis was noted in a study by Chandhoke and McAninch (1988). Although critical to the initial evaluation of traumatic urinary tract injury, the presence or absence of hematuria should not be the sole determinant in the assessment of a patient with suspected renal trauma. Because the significance of hematuria varies with blunt and penetrating mechanisms, the importance of proper staging of renal injuries cannot be underscored.

Indications for Renal Imaging

The criteria for radiologic imaging include (1) all penetrating trauma patients with a likelihood of renal injury (abdomen, flank, or low chest) who are hemodynamically stable; (2) all blunt trauma with significant mechanism of injury, specifically rapid deceleration as would occur in a motor vehicle accident or a fall from heights; (3) all blunt trauma with gross hematuria; (4) all blunt trauma with hypotension defined as a systolic pressure of less than 90 mm Hg at any time during evaluation and resuscitation; and (5) all pediatric patients with greater than 5 red blood cells (RBCs)/HPF. Patients who are hemodynamically unstable after initial resuscitation require surgical intervention.

The best indicator of renal injury is hematuria, defined as 5 RBCs/HPF by most authors. Historically, when used as the sole indication for renal imaging, IVP and other studies found a low incidence of renal abnormalities. An extensive prospective study based at San Francisco General Hospital evaluating indications for radiographic imaging has been ongoing for more than 25 years. The findings have been updated on three reports (Mee et al, 1989; Miller and McAninch, 1995; Nicolaisen et al, 1985). Figure 42–2 provides the results of the study for adult blunt renal trauma. On the basis of information from this study, all blunt trauma patients with gross hematuria and patients with microscopic hematuria and shock (systolic blood pressure <90 mm Hg any time during evaluation and resuscitation) should undergo renal imaging, usually with CT using intravenous contrast.

Figure 42–2 Algorithm demonstrating the results of the authors’ study on radiographic assessment of renal injuries. In adults with blunt trauma, imaging studies may be performed selectively. SBP, systolic blood pressure.

(From Miller KS, McAninch JW. Radiographic assessment of renal trauma. Our 15-year experience. J Urol 1995;154:352–5.)

Patients with microscopic hematuria without shock can be observed clinically without imaging studies. As first noted by Miller and McAninch (1995), several studies confirm the findings that these patients rarely have a significant injury (<0.0016%). However, if possible renal injury is suspected on the basis of history or examination, imaging should be performed. For example, blunt rapid deceleration injuries such as high-speed motor vehicle accidents or falls from great heights are at risk for vascular injury. These can cause significant injury (usually ureteral avulsion or vessel injury) in the absence of microscopic hematuria.

Penetrating injuries with any degree of hematuria should be imaged. In a report by Carroll and McAninch (1985), 27 of 50 patients with penetrating renal trauma had microscopic hematuria. Three of these patients had 0 to 3 RBCs/HPF, and one of the three had a renal pedicle injury. The presence of shock, degree of hematuria, location of the entry wound, and type of injury do not permit reliable discrimination among categories.

Pediatric patients (younger than 18 years) sustaining blunt renal trauma must be carefully evaluated. Children are known to be at a greater risk for renal trauma than adults after blunt abdominal injury (Brown and colleagues, 1998a). For pediatric patients, liberal use of imaging studies should be considered, especially in the setting of high-speed/high-energy deceleration injuries (Buckley and McAninch, 2004). Children have a high catecholamine output after trauma, which maintains blood pressure until approximately 50% of blood volume has been lost. A recent review confirmed that the decision to image pediatric trauma cases on the basis of the adult criteria of gross hematuria, shock, and significant deceleration injury appropriately identified potential renal injuries just as they would in adult patients (Santucci et al, 2004).

Imaging Studies

Contrast-enhanced computed tomography (CT) is the gold standard for genitourinary imaging in renal trauma (Bretan et al, 1986; Federle et al, 1987). Highly sensitive and specific, CT provides the most definitive staging information: Parenchymal lacerations are clearly defined; extravasation of contrast-enhanced urine can easily be detected (Fig. 42–3); associated injuries to the bowel, pancreas, liver, spleen, and other organs can be identified; and the degree of retroperitoneal bleeding can be assessed by the size and dimensions of the retroperitoneal hematoma. Lack of uptake of contrast material in the parenchyma suggests arterial injury. The added anatomic detail for diagnosis of renal contrast extravasation and parenchymal/vascular injuries has translated into improved confidence in our ability to nonoperatively manage major injuries.

Figure 42–3 Computed tomography scan of a right renal stab wound (grade IV), demonstrating extensive urinary extravasation and large retroperitoneal hematoma.

Currently, spiral CT is being used in many centers to evaluate renal injuries (Brown et al, 1998b). Arteriovenous scanning (typically 80 seconds after contrast administration) provides visualization of the kidneys in the nephrogenic phase of contrast excretion and is necessary to detect arterial extravasation. Injury to the renal collecting system may be missed; contrast material has not had time to be excreted into the parenchyma and collecting system adequately. Repeated/delayed scanning of the kidneys 10 minutes after injection of contrast identifies parenchymal lacerations and urinary extravasation accurately and reliably. Expert opinion holds that delayed films may be omitted when the kidneys are deemed normal, and no perinephric, retroperitoneal, pelvic, or perivesical fluid is present (Santucci et al, 2004). Findings on CT that raise suspicion for major injury are (1) medial hematoma, suggesting vascular injury; (2) medial urinary extravasation, suggesting renal pelvis or ureteropelvic junction avulsion injury; and (3) lack of contrast enhancement of the parenchyma, suggesting arterial injury.

One major limitation of CT is the inability to define a renal venous injury adequately. With normal arterial perfusion, the parenchyma appears normal and the collecting system may contain contrast material. A medial hematoma accompanying the preceding findings strongly suggests a venous injury.

Historically, excretory urography was the most commonly used modality to evaluate genitourinary injuries. Largely replaced by CT, a limited role includes the intraoperative “single-shot” IVP. The indications are uncommon, but when the surgeon encounters an unexpected retroperitoneal hematoma surrounding a kidney during abdominal exploration, the study can provide essential information. The main purpose of the one-shot IVP is to assess the presence of a functioning contralateral kidney and to radiographically stage the injured side. The technique is key to gaining important information and minimizing the time involved: only a single film is taken 10 minutes after intravenous injection (IV push) of 2 mL/kg of contrast material. If findings are not normal or near normal, the kidney should be explored to complete the staging of the injury and reconstruct any abnormality found.

Morey and coworkers (1999) have reported their experience with single-shot intraoperative IVP for the immediate management of renal injuries; in 50 patients, the film quality was adequate to avoid renal exploration in 32%. This report supports the value of this intraoperative imaging technique when done properly.

Other imaging modalities have a limited role in the evaluation of genitourinary trauma. Sonography is being used with greater frequency in the immediate evaluation of injuries and can facilitate the rapid diagnosis of intraabdominal injuries (i.e., hemoperitoneum). However, the study cannot clearly delineate parenchymal lacerations, vascular disruptions, collecting system injuries, and urinary extravasation in the acute setting. If necessary, sonography can confirm the presence of two kidneys and can define a retroperitoneal hematoma. With the advent of power Doppler or other techniques such as ultrasound contrast, perhaps more functional information will be obtainable in the future from renal ultrasound in the trauma setting.

In select cases, renal arteriography can be considered an adjunct diagnostic imaging technique with possible therapeutic implications. Angiography is largely used to define arterial injuries suspected on CT or to localize and control arterial bleeding (Fig. 42–4). Renal embolization has proved useful in the primary setting with persistent bleeding in a hemodynamically stable patient. Case reports have shown that endovascular stenting can be used to treat traumatic renal artery dissection, but technical problems surrounding the need for postprocedure anticoagulation have not yet been solved. Pseudoaneurysms and arteriovenous fistula are treated by angiographic embolization to stop secondary hemorrhage. Superselective embolization therapy for renal trauma now provides an effective and minimally invasive technique to avoid unnecessary exploration that could otherwise result in a nephrectomy.

Figure 42–4 Angioembolization of renal laceration: A, Arteriography demonstrating active arterial bleeding. B, Coil embolization used to control bleeding. Note presence of coil and large, triangular area of infarct.

Isolated Renal Injuries

The presence of concomitant injuries often influences the management of renal trauma; approximately 80% to 90% of renal injuries have major associated organ injury requiring surgical exploration. Although the majority of grade I to III renal injuries can be managed nonoperatively with excellent renal preservation, patients with grade V injuries, defined as hemodynamically unstable with major renovascular insults or multiple grade IV parenchymal lacerations, usually require immediate life-saving operative exploration. Thus a special subset of high-grade injuries, specifically an isolated grade IV insult without significant associated abdominal injuries, occurs more commonly from blunt trauma and in most circumstances can be managed nonoperatively.

Expectant management strategies of isolated kidney injuries allow for maximal renal preservation. Superselective embolization therapy for renal trauma provides an effective and minimally invasive means to stop active bleeding from parenchymal lacerations and even segmental arterial injury. Interventional radiology skills and techniques allow selective embolization of even the smallest parenchymal vessels with maximal preservation of functioning parenchyma. However, one must recognize that renal vessels are end arteries, and any selective vessel embolization results in tissue death peripheral to the embolized site.

The management of severe renal lacerations must balance two major issues: the increased incidence of nephrectomy in patients undergoing immediate as opposed to delayed renal exploration and the associated morbidity of patients managed expectantly. The experience with endovascular therapy for severe renal hemorrhage continues to grow. In a literature review of 10 case series, most renal traumas including most grade IV injuries were effectively managed with embolization therapy with a clinical success rate of 80% (Breyer, 2008). Indications for angiography with embolization therapy have included bleeding from a renal segmental artery with or without parenchymal laceration, unstable condition with grade III to IV injury, arteriovenous fistula or pseudoaneurysm, persistent gross hematuria, and/or blood loss exceeding 2 units in 24 hours. Future considerations to better define the criteria for angiography and embolization in patients with renal hemorrhage continue to be an area of research interest.

In special clinical circumstances, endovascular stents have been used with reported success during angiography in patients with renal artery thrombosis occurring from intimal flaps (Goodman et al, 1998). Longer-term follow-up and more cases are necessary to determine whether this will be a successful management approach, especially considering that most stents require anticoagulation after placement, which may not be possible in a trauma patient.

Those patients with grade IV parenchymal lacerations who have well-contained hematomas should be observed expectantly. An 88% renal salvage rate of isolated grade IV renal injuries managed conservatively has recently been documented (Buckley and McAninch, 2006). They should be closely monitored for bleeding, with vital signs, serial hematocrit readings, and pulse rates. If urinary extravasation is present, serial renal CT scanning can be considered. If significant urinary extravasation persists, placement of an internal ureteral stent for drainage often prevents prolongation of the extravasation and decreases the chance of perirenal urinoma formation. Experts recommend the use of broad-spectrum antibiotics to decrease the possibility of perinephric abscess, although the authors are aware of no convincing research that they decrease infection rates.

If nonoperative management is selected for a patient with gross hematuria whose injury has been well staged with appropriate imaging, hospital admission and bed rest are required. Once the gross hematuria clears, ambulation is allowed; should gross hematuria recur, bed rest is reinstated. Ambulation without any sequelae allows hospital discharge with close clinical follow-up. The patient should be watched for and warned about the possibility of renovascular hypertension and delayed bleeding.

Renal Exploration

Surgical exploration of the acutely injured kidney is best done by a transabdominal approach, which allows complete inspection of intra-abdominal organs and bowel. In some reported series of penetrating injuries, associated organ injury has been noted to be as high as 94% (McAninch et al, 1993). Injuries to the great vessels, liver, spleen, pancreas, and bowel can be identified and stabilized if necessary before renal exploration.

The surgical approach to renal exploration is shown in Figure 42–6 (McAninch and Carroll, 1989). The renal vessels are isolated before exploration to provide the immediate capability to occlude them if massive bleeding should ensue when Gerota’s fascia is opened (Scott and Selzman, 1966). The transverse colon is lifted superiorly onto the chest, and the small bowel is lifted superiorly and to the right. This exposes the midretroperitoneum. An incision is made over the aorta in the retroperitoneum just superior to the inferior mesenteric artery. The incision is extended superiorly to the ligament of Treitz. Exposure of the anterior surface of the aorta is accomplished and followed superiorly to the left renal vein, which crosses the aorta anteriorly. With a vessel loop controlling the vein, the anatomic relationships of the right and left renal arteries as they leave the aorta provide the ability to isolate and secure these structures with vessel loops. The right renal vein can be secured through this incision; if this proves difficult, reflecting the second portion of the duodenum provides excellent exposure to the vein.

Figure 42–6 The surgical approach to the renal vessels and kidney. A, Retroperitoneal incision over the aorta medial to the inferior mesenteric vein. B, Anatomic relationships of the renal vessels. C, Retroperitoneal incision lateral to the colon, exposing the kidney.

Large hematomas may extend over the aorta and obscure the landmarks for the planned initial retroperitoneal incision. In such instances, the inferior mesenteric vein can be used as an anatomic guide for an appropriate incision. By making the retroperitoneal incision just medial to the inferior mesenteric vein and dissecting through the hematoma, the anterior surface of the aorta can be identified and followed superiorly to the crossing left renal vein.

The kidney is exposed by incising the peritoneum lateral to the colon, followed by mobilization off Gerota fascia. This maneuver often requires release of the splenic (left) or hepatic (right) attachments of the colon. Gerota fascia is then opened and the kidney with injury is completely dissected from the surrounding hematoma. Should troublesome bleeding develop, the previously isolated vessels can be temporarily occluded with a vascular clamp or a vessel loop tourniquet.

Renal Reconstruction

The principles of renal reconstruction after trauma include complete renal exposure, measures for temporary vascular control, debridement of nonviable tissue, hemostasis by individual suture ligation of bleeding vessels, watertight closure of the collecting system if possible, coverage or reapproximation of the parenchymal defect, and judicious use of drains (Fig. 42–7).

Figure 42–7 Technique for partial nephrectomy: A, total renal exposure; B, sharp removal of nonviable tissue; C, hemostasis obtained and collecting system closed; D, defect covered.

Renorrhaphy is illustrated in Figure 42–8 and involves exposure of the kidney, debridement of nonviable tissue, hemostasis obtained with absorbable 4-0 chromic sutures on bleeding vessels (the addition of hemostatic agents such as Floseal [Baxter; Deerfield, IL] may also be helpful), closure of the collecting system, and approximation of the margins of the laceration (3-0 absorbable suture) with the use of renal capsule and an absorbable hemostatic agent bolster such as Gelfoam (Pfizer; New York, NY).

Figure 42–8 Technique for renorrhaphy: A, typical injury in midportion of kidney; B, debridement, hemostasis, and collecting system closure; C, approximation of parenchymal margins; D, sutures tied over gelatin sponge bolster.

When polar injuries cannot be reconstructed, a partial nephrectomy should be done and all nonviable tissue removed, hemostasis obtained, and the collecting system closed. The open parenchyma should then be covered when possible by a pedicle flap of omentum (see Fig. 42–7). With its rich vascular and lymphatic supply, omentum promotes wound healing and decreases the risk of delayed bleeding and urinary extravasation. Should it not be available, the use of absorbable mesh, peritoneal graft, or retroperitoneal fat has been successful (Master and McAninch, 2006).

Hemostatic agents such as Floseal are potent and have an increasing role in the management of genitourinary trauma (Evans and Morey, 2006). On the basis of experience from nephron-sparing surgery, gelatin matrix was applied to a porcine model of complex renal trauma and demonstrated less mean blood loss than conventional suture treatment (Hick et al, 2005; Pursifull et al, 2006).

In a high percentage of major renal injuries, intra-abdominal structures are also injured, the liver and spleen being the most common. Injuries to the colon, pancreas, and stomach also occur frequently, and in previous years total nephrectomy was suggested because of the high complication rate with attempted renal salvage. However, renal repair in these injuries has been successful with minimal complications (Rosen and McAninch, 1994; Wessells and McAninch, 1996). Drains should be used liberally in these repairs.

Renovascular Injuries

Renovascular injuries following trauma are uncommon and often have associated injuries requiring operative intervention. For major renovascular injuries, speedy nephrectomy is advocated. In rare instances where repair is possible, renal salvage rates are low, exemplified by a 33% renal salvage rate for main renal artery reconstruction even in the most expert of hands (Elliott et al, 2007). Vascular repair requires occlusion of the involved vessel with vascular clamps. The lacerated main renal vessels injured by penetrating trauma can be repaired with 5-0 nonabsorbable vascular suture (Fig. 42–9).

Figure 42–9 Vascular injuries. Left, Venous injuries may occur in the main renal vein or the segmental branches. Middle, Repair of main renal vein. Right, Ligation of segmental branch can be done safely.

Main renal artery thrombosis from blunt trauma occurs secondary to deceleration injuries. The mobility of the kidney results in stretch on the renal artery, which in turn causes the arterial intima, low in elastic fibers, to disrupt. The consequent thrombus occludes the vessel, rendering the kidney ischemic (Fig. 42–10). Prompt diagnosis by CT or angiography may lead to immediate renal exploration in the appropriate candidate in an attempt to salvage the kidney, but outcomes for salvage remain dismally low and nephrectomy is almost always required.

Figure 42–10 A, Movement of the kidney from blunt trauma (deceleration injury) causes stretch on the renal artery, resulting in rupture of the arterial intima and formation of a thrombus. B, Computed tomography of a left kidney with renal artery thrombosis, demonstrating lack of contrast material perfusion to the kidney. C, Arteriography demonstrating complete occlusion of the left renal artery secondary to thrombus formation.

Case reports of successful renal revascularization through the use of endovascular stents during angiography offer a new and perhaps promising approach to the problem of blunt trauma renal artery thrombosis caused by the intimal flap (Inoue et al, 2004). The great disadvantage of this approach has been the inability to effect anticoagulation in the polytrauma patient.

With delayed diagnosis (>8 hours), the kidney typically cannot be salvaged (Cass, 1989). With a 15-year experience, Haas and colleagues (1998) have reported that surgical revascularization was seldom successful in renal artery thrombosis and at least 43% of their patients with repairs developed hypertension. Hypertension was also common in those observed nonoperatively. When repair is attempted in renal artery thrombosis, the area of injury (noted by a visible contusion on the vessel) should be excised and a replacement graft done, preferably with hypogastric or splenic artery. Many patients with renal vascular injury are critically injured, with numerous associated organ injuries; time constraints thus limit attempts at vascular repair and a nephrectomy must be done.

Segmental renal arterial injuries result in ischemic infarction to a segment of the kidney. These should be observed nonoperatively when diagnosed unless associated with a parenchymal laceration. Should the laceration with infarction be greater than 20% of the parenchyma, careful consideration should be given to endovascular embolization or surgical correction.

Injuries to the main renal vein require repair with fine vascular suture (5-0) (see Fig. 42–9). Partial occlusion of the vein is ideal for repair, but in some instances total occlusion with vascular clamps is necessary; if so, temporary occlusion of the renal artery is necessary.

Damage Control

Coburn (2002) has noted the benefit of damage control to improve renal salvage. The wound and area around the injured kidney are packed with laparotomy pads to control bleeding with a planned return in 24 hours to explore and evaluate the extent of injury. This approach is commonly used by trauma surgeons in patients with extensive injuries and has long been used by general surgeons. It may well be useful in managing complex renal injuries to avoid total nephrectomy.

Indications for Nephrectomy

The ability to reconstruct an injured kidney depends on numerous factors. The unstable patient, with low body temperature and poor coagulation, cannot risk an attempt at renal repair if a normal contralateral kidney is present (Davis et al, 2006). As noted earlier, damage control (packing the wound to control bleeding and attempting to correct metabolic and coagulation abnormalities) with a plan to return for corrective surgery within 24 hours provides an option in management. Total nephrectomy would be indicated immediately in extensive renal injuries when the patient’s life would be threatened by attempted renal repair. When Nash and colleagues (1995) examined the reasons for nephrectomy in patients with renal injuries, 77% required removal because of the extent of parenchymal, vascular, or combined injury and the remaining 23% required nephrectomy in otherwise reconstructable kidneys because of hemodynamic instability.