Paediatric Urology

24. PAEDIATRIC UROLOGICAL TRAUMA

Trauma is the leading cause of morbidity and mortality in children [1417]. Trauma is generally caused by either blunt injuries from falls, car accidents, sports injuries, physical assault or sexual abuse, or penetrating injuries, usually due to falls onto sharp objects or from gunshot or knife wounds.

24.1. Paediatric renal trauma

24.1.1. Epidemiology, aetiology and pathophysiology

Of all renal injuries, approximately 25% occur in children, 79% of which are low-grade (I, II or III) and 21% of which are high-grade (IV or V) [1418]. The most common cause of renal injury is blunt abdominal trauma (90%), in which the kidney is the most commonly affected organ, accounting for approximately 10% of all blunt abdominal injuries [1419]. Children are more likely than adults to sustain renal injuries after blunt trauma due to several anatomical factors, including decreased perirenal fat, weaker abdominal musculature, a relatively large size of the kidney in relation to the rest of the body, foetal lobulations which result in a higher likelihood of a local parenchymal disruption, and a less-ossified rib cage [1423]. Blunt renal trauma is also frequently associated with injury to other organs [1424].

24.1.2. Classification systems

Renal injuries are classified according to the kidney injury scale of the American Association for the Surgery of Trauma (Table 11) [1425].

Table 11: Renal injury classified according to the kidney injury scale of the American Association for the Surgery of Trauma [1425]

24.1.3. Diagnostic evaluation

In a child who has sustained blunt abdominal trauma, renal involvement can often be suspected from the history, physical examination and laboratory evaluation. Renal involvement may be associated with abdominal or flank tenderness, lower rib fractures, fractures of vertebral pedicles, trunk contusions and abrasions, and haematuria. Vital signs should be monitored during the initial evaluation and give the most reliable indication of the urgency of the situation. It is important to consider that children, unlike adults, are able to maintain their blood pressure, even in the presence of hypovolaemia, due to compliance of the vascular tree and mechanisms for cardiac compensation [1420]. All the clinical aspects involved must be considered, including the history, physical examination, consciousness of the child, overall clinical status and laboratory findings to decide on the diagnostic algorithm and whether or not a child requires further imaging studies. In severe renal injuries, 65% of patients suffer gross haematuria and 33% non-visible haematuria, while 2% have no haematuria at all [1421]. There have been several reports of significant renal injuries that manifest with little or even no blood in the urine [1422].

24.1.3.a. Choice of imaging method

FAST ultrasound
In severe trauma or haemodynamically instable patients, focussed assessment sonography in trauma (FAST) ultrasound can be used to identify a hemoperitoneum with high specificity (95%) but low sensitivity (33-89%) and negative predictive value (50%). However, sensitivity and specificity for kidney trauma and retroperitoneal haemorrhage is low. Therefore, it is not recommended as a sole diagnostic tool [1426].

Computed tomography
Computed tomography scanning is the imaging modality of choice in patients with suspicion of renal injuries, since it is widely available, quick and provides accurate grading [1427]. Ideally, CT is performed in three phases: the arterial phase to detect vascular injury or active bleeding, the nephrogenic phase to detect parenchymal lacerations, and the delayed phase to detect injury of the collecting system or ureter. Moreover, CT scanning can detect associated other intra-abdominal injuries, which are frequently associated with renal trauma, particularly in grade III-V [1424]. Scanning protocol should be adapted for paediatric patients according to the principles of ALARA (as low as reasonably achievable) to reduce the amount of ionising radiation as much as possible.

Ultrasound
(Contrast-enhanced) US can be considered as the sole investigation in patients with mild symptoms and no other indications for CT scanning, where the mechanism of trauma and the condition of the patient do not suggest the presence of injury to other organs or the urinary tract. Although conventional US is not sufficiently accurate to grade renal trauma, there could be a role for contrast-enhanced ultrasound (CEUS) to identify parenchymal lesions. However, this technique cannot detect injuries to the urinary tract or collecting system, since the contrast agent is not excreted by the kidney [1428]. Ultrasound can be performed in follow-up of a renal trauma to reduce the amount of radiation. However, even in high-grade renal trauma, routine repeat imaging may be avoidable in stable, asymptomatic patients [1429].

24.1.4. Disease management

The modern management of trauma is multidisciplinary, requiring paediatricians, emergency physicians, surgeons, urologists and other specialties as necessary.

Nonsurgical conservative management with bed rest, fluids and monitoring has become the standard approach for treating blunt renal trauma. In high-grade renal injuries, a conservative approach is effective and recommended for hemodynamically stable children [1430]. However, this approach requires close clinical observation and intermittent reassessment of the patient’s overall condition. Therefore, a good initial trauma CT with delayed images to check for urinary extravasation is recommended, since patients with a urine leak have higher rates of morbidities, including febrile episodes and an increased requirement of operative or image-guided interventions [1431]. However, early drainage does not seem to prevent persistent urinary extravasation or complications [1432]. Therefore, reserve stenting and/or percutaneous drainage only when the patient is symptomatic [1433]. Emergency intervention is indicated only for haemodynamic instability and angioembolisation, if available, for ongoing or delayed bleeding is preferred compared to open surgery. The results of angioembolisation were evaluated and were successful in 92% of patients with Grade III-IV (294/322) and 76% of Grade V (63/82) injuries. Moreover, the success rate was 90% (312/346) in hemodynamically stable patients, but only 63% (42/66) in hemodynamically unstable patients [1434]. Absolute indications for surgery include persistent bleeding into an expanding or unconfined haematoma with haemodynamic instability. Relative indications for surgery are massive urinary extravasation and extensive nonviable renal tissue [1435].

Follow-up
In paediatric patients with renal trauma, routine blood pressure checks to diagnose hypertension is recommended in the long-term follow-up, since post-traumatic renal hypertension rate varies between 4.2 and 18%, particularly in cases with concomitant vascular injury [1430,1436]. However, there is a dearth of long-term data on the risk of developing hypertension in children.

24.1.5. Recommendations for the diagnosis and management of paediatric renal trauma

24.2. Paediatric ureteral trauma

Injuries to the ureter are rare. The ureter is well-protected. The upper part is protected by its close proximity to the vertebral column and paraspinal muscles and the lower part by its route through the bony pelvis. In addition, the ureter is a small target, and both flexible and mobile. This also means that ureteral injuries are caused more often by penetrating trauma than blunt trauma [1437]. Since the ureter is the sole conduit for urinary transport between the kidney and the bladder, any ureteral injury can threaten the function of the ipsilateral kidney.

24.2.1. Diagnostic evaluation

As there are no classical clinical symptoms suggestive of ureteral trauma, it is important to carry out a careful diagnostic workup using various imaging modalities. Unfortunately, initial imaging studies, such as IVP and routine CT scans, are unreliable. A study of 11 disruptions of the ureteropelvic junction found that 72% had a normal or nondiagnostic IVP on initial studies [1437]. Diagnostic accuracy of CT scanning can be improved by performing a delayed CT scan up to ten minutes after injection of the contrast material [1438]. The most sensitive diagnostic test is a retrograde pyelogram.

It is not uncommon for patients to present several days after the injury, when the urinoma produces flank and abdominal pain, nausea and fever. Due to symptoms being often vague, it is important to remain suspicious of a potential undiagnosed urinary injury following significant blunt abdominal trauma in a child.

24.2.2. Management

Immediate repair during abdominal exploration is rare. Minimally invasive procedures are the method of choice, especially since many ureteral injuries are diagnosed late after the traumatic event. Percutaneous or nephrostomy tube drainage of urinomas can be successful, as well as internal stenting of ureteral injuries [1439]. If endoscopic management is not possible, primary repair of partial lacerations should be carried out together with internal stenting. The management of complete lacerations, avulsions or crush injuries depends on the amount of ureter lost and their location. If there is an adequate healthy length of ureter, a primary ureteroureterostomy can be performed. If primary reanastomosis is not achievable, distal ureteral injuries can be managed using a psoas bladder hitch, Boari flap or even nephropexy. Proximal injuries can be managed using transureteroureterostomy, autotransplantation or ureteral replacement with bowel or appendix [1440].

24.2.3. Recommendations for the diagnosis and management of paediatric ureteral trauma

24.3. Paediatric bladder injuries

The paediatric bladder is less well-protected than the adult bladder, and is therefore more susceptible to injuries, especially when full, due to:

• its higher position in the abdomen and its exposure above the bony pelvis;
• the fact that the abdominal wall provides less muscular protection; and
• the fact that there is less pelvic and abdominal fat surrounding the bladder to cushion it during trauma.

Blunt trauma is the most common cause of significant bladder injury. In adults, bladder injury is often associated with pelvic fractures. This is less common in children, because the paediatric bladder is situated above the pelvic ring. In a large prospective study, only 57% of children with pelvic fractures also had a bladder injury, compared to 89% of adults [1441].

24.3.1. Diagnostic evaluation

The characteristic signs of bladder injury are suprapubic pain and tenderness, an inability to urinate, and visible haematuria (95% of injuries). Patients with a pelvic fracture and visible haematuria present with a bladder rupture in up to 45% of cases [1442].

The diagnosis of bladder rupture can be difficult in some cases. The bladder should be imaged both when fully distended and after drainage using standard radiography or with axial imaging (e.g. CT scan). Optimal imaging results are achieved through retrograde filling of the bladder using a catheter. Despite advances in CT imaging, the bladder must still be filled to capacity to accurately diagnose a possible bladder injury [1443].

Blunt injuries to the bladder are categorised as:

• contusions with damage to the bladder mucosa or muscle, without loss of bladder wall continuity or extravasation; and
• ruptures, which are either intraperitoneal or extraperitoneal.

Intraperitoneal bladder ruptures are more common in children due to the bladder’s exposed position and the acute increase in pressure during trauma. These factors cause the bladder to rupture at its weakest point, i.e. at the dome. Extraperitoneal lesions occur in the lower half of the bladder and are almost always associated with pelvic fractures. A cystogram should demonstrate extravasation into the perivesical soft tissue in a typical flame pattern and the contrast material is confined to the pelvis.

24.3.2. Management

Contusions usually present with varying degrees of haematuria and are treated with catheter drainage alone.

24.3.2.a. Intraperitoneal injuries

The accepted management of intraperitoneal bladder ruptures is open surgical exploration and primary repair. Postoperative drainage with a suprapubic tube is mandatory. Recent data suggest that transurethral drainage may be equally effective, with fewer complications, resulting in shorter periods of diversion [1444]. Usually, after approximately seven to ten days, a repeat cystogram is performed to ensure adequate healing.

24.3.2.b. Extraperitoneal injuries

Nonoperative, supportive management with catheter drainage for seven to ten days is the method of choice for extraperitoneal bladder rupture. However, if there are bone fragments within the bladder, these must be removed and the bladder must then be repaired and drained according to the principles for treating intraperitoneal ruptures [1445].

24.3.3. Recommendations for the diagnosis and management of paediatric bladder injuries

24.4. Paediatric urethral injuries

Except for the penile part of the urethra, the paediatric urethra is quite well-protected. In addition, the shape and elasticity of the paediatric urethra mean that the urethra is seldom injured by trauma. However, a urethral injury should be suspected in any patient with a pelvic fracture or significant trauma to the perineum until confirmed, otherwise by means of a diagnostic workup.

24.4.1. Diagnostic evaluation

Patients with suspected urethral trauma and pelvic fractures usually present with a history of severe trauma, often involving other organ systems.

Signs of urethral injury include blood at the meatus, visible haematuria, pain during voiding or an inability to void. There may also be perineal swelling and haematoma involving the scrotum. A rectal examination to determine the position and fixation of the prostate is important in any male with a suspected urethral injury. The prostate (although small), as well as the bladder, may be displaced up out of the pelvis, especially in membranous urethral trauma.

Radiographic evaluation of the urethra requires a retrograde urethrogram. It is important to expose the entire urethral length, including the bladder neck. If a catheter has already been placed and, if urethral trauma is suspected, the catheter should not be removed. Instead, a small infant catheter can be placed into the distal urethra along the catheter to allow the injection of contrast material for a diagnostic scan [1446].

24.4.2. Disease management

As these patients may be unstable due to the nature of their injuries, the urologist’s initial responsibility is to provide a method of draining and monitoring urine output.

A transurethral catheter should only be inserted if there is a history of voiding after the traumatic event, and if a rectal and pelvic examination, as described above, has not suggested a urethral rupture. If the catheter does not pass easily, an immediate retrograde urethrogram should be performed. A suprapubic tube can be placed in the emergency department percutaneously, or even in the operating room if the patient must undergo immediate exploration due to other life-threatening injuries.

There are often no associated injuries with a bulbar urethral or straddle injury, and management is therefore usually straightforward. In these cases, a transurethral catheter is the best option for preventing urethral bleeding and/or painful voiding [1447].

The initial management of posterior urethral injuries remains controversial, mainly regarding the long-term results with primary realignment compared to simple suprapubic drainage with later reconstruction.

The main goals in the surgical repair of posterior urethral injuries are:

• providing a stricture-free urethra; and
• avoiding the complications of urinary incontinence and erectile dysfunction.

Anterior urethral injury
The data for anterior urethral injury repair is much the same as for adults. Small lacerations can be repaired by simple closure. Complete ruptures without extensive tissue loss are treated with anastomotic repair [1448]. Penetrating injuries require peri- and postoperative antibiotic treatment [1449].

Immediate urethroplasty is generally performed in blunt injuries. The long-term outcomes (patency rate, potency rate) of adult patients treated with immediate urethroplasty are similar to those initially treated with suprapubic diversion and delayed urethroplasty [1450]. The main advantage of performing immediate urethroplasty is that this strategy significantly reduces the time to spontaneous voiding from two to six months to three weeks on average. Spongiosal contusion and haematoma during immediate urethroplasty will make the operation technically more demanding. Therefore, immediate urethroplasty should be performed by a dedicated urethral surgeon [1451].

Posterior urethral injury
Unlike anterior urethral injuries with immediate realignment, in children with posterior urethral injuries, a staged approach with delayed repair may be more appropriate.

In children, there is significantly less experience with delayed repair, with a large paediatric series of delayed repair in 68 boys reporting successful voiding and a continence rate of 90% [1452]. Another study reported strictures and erectile dysfunction in 67% of boys, although all the boys were continent postoperatively [1247]. A follow-up study on 15 patients who underwent delayed urethroplasty for blunt urethral trauma during childhood reported high long-term success rates, with a low rate of long-term urinary and sexual dysfunction in adulthood [1453].

Revision surgery
A large study of revision urethroplasty analysing revision urethroplasty following pelvic floor urethral injuries in children and adolescents demonstrated that these injuries appeared to be more common in the developing world, with more complex findings and longer gaps. In support of the above findings, these patients were best managed with delayed transperineal repair with self-reported success of up to 85% [1454]. On the other hand, a small prospective study demonstrated good results with immediate primary endoscopic realignment in patients with posterior urethral and bladder neck injuries [1455]. This may serve as an alternative to those with permitting endoscopic anatomy post-injury. A large study exploring outcomes of various urethroplasty techniques in both boys and girls demonstrated that most paediatric pelvic floor urethral injuries can be addressed through a transperineal approach with reasonable long-term outcomes (> 80%), however, up to 25% of patients require further endoscopic/open procedures during follow-up. In challenging cases, salvage procedures utilising vascular-based flaps as a urethral substitute can yield good results. The numbers lost to follow-up, however, were significant at 40.6% [1456].

In a study of 18 boys undergoing urethroplasty for strictures (traumatic/iatrogenic), post-void dribbling and urgency were the main patient-reported outcome measures (PROMs) following surgery, with universally high satisfaction rates. Patient-reported outcome measures are an important consideration for urologists performing these procedures on children, because they will likely need continued long-term follow-up [1457]. In those who have previously experienced a failed urethroplasty following pelvic fracture-associated urethral injuries, most cases of recurrent posterior urethral strictures of < 3cm in length can be treated with a perineal urethroplasty with reasonable success rates. Complex and long-segment (higher than 3cm) strictures require use of ancillary procedures such as transpubic urethroplasty, substitution urethroplasty and Mitrofanoff appendicovescostomy with complication rates in adolescents of 33% [1458].

24.4.3. Recommendations for the diagnosis and management of paediatric trauma

24.5. Urosepsis

Refer to Chapter 12 on urinary tract infections in children.