Urethral injury is a relatively rare medical condition accounting for less than 1% of all emergency department visits in the United States. Injury patterns vary and encompass urethral crush, bruising, laceration, and transection. Urethral injuries are never life-threatening, but if left untreated can cause significant morbidity. While most injuries are iatrogenic, traumatic etiologies often caused by high energy mechanisms, certainly do carry mortality threats. The injury extent and anatomical location of urethral injuries are formative in the development of a management plan.
Clinicians classically use several anatomical landmarks in the evaluation, classification, and management of urethral injuries, which is particularly important among male patients. The male urethra subdivides into anterior and posterior divisions delineated by the urogenital diaphragm. The anterior segment consists of the penile and bulbar urethra while the posterior urethra consists of the membranous and prostatic portions.
The etiology of urethral injuries can commonly subdivide as anterior or posterior injuries. With some exceptions, anterior injuries involve a crushing mechanism, whereas posterior injuries involve sheering forces. Injury to anterior urethra is more common to motor vehicle trauma, straddle injuries, and blunt/penetrating trauma, whereas pelvic fractures and iatrogenic etiologies are more consistent with injury to the posterior urethra. Iatrogenic injury secondary to improper catheterization and transurethral instrumentation is the most common cause worldwide.
Among men, some estimate that improper urinary catheterization accounts for between 6 to 32% of all urethral injuries. Having an enlarged prostate was the most common risk factor as these individuals have frequent visits to the emergency department for catheter placement. While common, iatrogenic urethral injuries usually involve minor tears that heal on their own and carry a good prognosis. Urethral injury in females most commonly occurs as an obstetrical complication with 10.3 per 1000 vaginal deliveries resulting in some degree of urethral injury. Damage to the anterior urethra is more common in straddle injuries associated with motor vehicle trauma, whereas pelvic fractures are more consistent with injury to the posterior urethra. Other notable causes of urethral injuries include cases of penile fracture during vigorous sexual intercourse causing simultaneous urethral injury and less frequently, self-mutilation among psychiatric patients and foreign body associated injuries.
Some sources suggest that up to 10% of patients involved in significant blunt or penetrating trauma have a urethral injury. Among these, young males, ages 11 to 25, present most commonly. Men are nearly ten times more likely to experience a urethral injury than women. Anatomically, females are at lower risk because of their comparatively shorter and more mobile urethra and the mobility of the uterus. Despite this gender advantage, the incidence of urethral injury among females with pelvic fractures is as high as 6%.
Urethral injuries range from tissue contusions to complete open urethral transections. In the acute phase, local tissue swelling or urethral disruption can cause acute urinary retention. If not addressed, for instance, in an intubated patient, this retention can lead to hydronephrosis, acute kidney injury, or acute renal failure in extreme cases. For this reason, there is an overwhelming consensus to prioritize bladder decompression. To some extent, all urethral injuries cause scar tissue formation and, if significant enough, can lead to fibrosis, stenosis, and/or stricture formation. These can be benign or can potentially cause clinically significant urinary retention.
The constellation of historical and physical exam findings associated with a urethral injury is rarely occult. Patients typically present with the recent history of trauma, urological surgery, or sudden onset of pain during intercourse. Physical examination findings suggestive of urethral injury include blood at the urethral meatus, pain or inability to void, pelvic instability, palpable bladder secondary to inability to void, scrotal or labial swelling, high-riding prostate, and a "butterfly" pattern of bruising on the perineum. A high index of suspicion should be maintained if the patient presents with any of these physical exam findings. Furthermore, in the traumatic setting, The American College of Surgeons, as a part of the advanced trauma life support (ATLS) guidelines, emphasizes the triad of blood at the urethral meatus, inability to void and a palpable bladder as a cause for evaluation of urethral injury.
While controversy exists among practitioners, retrograde urethrography (RUG) is generally accepted as the gold standard modality for evaluation of the urethra. The RUG has good utility among trauma patients and is easily performed at the bedside. The procedure is performed by injecting 20 to 30 mL of diluted, water-soluble contrast into the urethral meatus and then obtaining an x-ray. RUG is highly sensitive in detecting urethral injuries but falls short in identifying the precise location of the injury and is somewhat operator-dependent. A positive RUG study will demonstrate the extravasation of contrast outside of the serpentine cylinder of the urethral tract. Several other imaging modalities can be options to evaluate urethral injuries. Computed tomography (CT) is the test of choice to assess the intra-abdominal urinary system, including the kidneys, ureters, and bladder. In many cases of blunt traumatic injury, a CT scan will be ordered but does not replace the need for a RUG as CT fails to evaluate the penile urethra sensitively. The use of magnetic resonance imaging is often logistically challenging, but some have advocated for its use among children with a urethral injury where advanced imaging is warranted. Lastly, the limited use of ultrasonography as a preliminary screening tool for urethral injury is another possibility. In the clinically suspicious setting of urethral injury, ultrasonography can be useful for the detection of air within the bulbocavernosus. If air is present, then more invasive radiographic studies such as a RUG or CT could be ordered.
Classification and proper description of urethral njuries are important in the development of treatment plans and inter-provider communication. Several classification systems exist. Perhaps the most common is the Unified Anatomical Mechanical Classification of Urethral Injuries and is as follows :
Once a urethral injury is suspected, an emergent consultation with urology should take place, or patients should transfer to a center with experienced urological specialists. Treatment of urethral injuries is often multifactorial and controversial. In the setting of severe multi-trauma, urethral injury is considered not immediately life-threatening. There are several main treatment principles upon which experts generally agree. The first is that if the patient cannot urinate or if they have blunt trauma to the anterior urethra, the urinary bladder should undergo decompression to prevent further extravasation of urine into the pelvic soft tissue and or abdomen. Next, all penetrating and open urethral injuries require surgical exploration and possible debridement. Finally, antibiotic administration is recommended to prevent subsequent secondary infection.
When urethral disruption is suspected, a suprapubic cystotomy tube, placed surgically, is the recommended course. This catheter will remain (with monthly exchanges) until urethral healing is complete and patency has been established- on average, between four weeks and three months.
Surgical intervention categorizes as immediate (0 to 10 days), delayed (10 to 14 days), and late (more than three months) repairs. Surgical intervention, when indicated, should either occur 1) as soon as possible in cases of penetrating trauma or open injury or 2) later in penile fracture injuries. Principles of surgical intervention involve debridement of penetrating or open urethral injuries, epithelial apposition, the establishment of bladder neck competence, and adequate blood supply to the anastomosis.
Urethral injuries are never life-threatening, but they are often closely associated with other significant blunt and penetrating traumatic injuries with significant comorbidities, which may complicate treatment. Prognosis is generally good, but many well documented long-term sequelae do exist. In cases that involve children, predicting the prognosis of a urethral injury is particularly difficult. The tissue is less developed and, therefore, less vascularized. A prognosis of sexual function and continence among children should be reserved until after puberty.
Among adults, the prognosis is marginal. Reports exist of several case series evaluating the complications associated with immediate, early, and late repair. Those that underwent immediate and early realignment experienced a 53% stricture, 5% incontinence, and 36% erectile dysfunction rates. Those that underwent suprapubic catheterization and late repair/realignment experienced a 97% stricture, 4% incontinence, and 19% erectile dysfunction rates.
Without question, urethral injury places the patient at risk for future morbidity. Complications can subdivide into early and late. Early complications center around secondary infection, including abscess formation, and in extreme cases, Fournier's gangrene. Late complications include urethral stricture and stenosis, fibrosis, obliteration of the urethral lumen, urethrocutaneous fistula formation, urinary incontinence, and erectile dysfunction. As the most common cause, iatrogenic injuries often involve partial urethral injuries and carry the best complication profile.
Management of small strictures of the anterior urethra is by dilatation, whereas more extensive strictures (greater than 2 cm) may require urethrotomy. Due to the thinner urethral wall of the bulbous urethra, posterior urethral injuries are managed conservatively if possible and then by urethroscopy if necessary.
Healthcare workers and patients that self-catheterize should receive education about the risks associated with improper catheterization techniques and have appropriate training to avoid urethral injuries. Also, community education on how to prevent motor vehicle injuries, and the proper use of seatbelts can decrease urethral injuries.
Appropriate referral/transfer should take place to centers with urological surgeons familiar with urethral reconstruction, particularly in pediatric patients. [Level 5]
Clinicians must maintain a high index of suspicion for urethral injuries, especially in blunt trauma. [Level 5]
While there are many imaging modalities described, RUG has continued to be the test of choice. [Level 3]
It is a known fact that there is a decreased incidence of urethral injury and false passage formation if healthcare practitioners perform dilation of urethral strictures with a guidewire. [Level 5]
An interprofessional team approach is the optimal management course, to include all specialties as cited above. Urology registered nursing staff is an invaluable asset in these cases, providing assistance before, during, and after all procedures, answering patient questions, and administering medications (e.g., antibiotics, analgesics, etc.) as needed. This interprofessional approach with open communication among all staff members and specialties optimizes results while minimizing adverse outcomes. [Level 5]
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