Urethral injury is the most common injury of the urinary system, accounting for 65% of urinary system injuries, the vast majority of which are seen in men, mostly in young adults, and only 1%-3% in women. Injuries can be broadly divided into three types of lacerations, transection injuries and blunt contusions. Lacerations can be caused by improper or violent use of cystoscopes, urethroscopes, metal urethral probes and other instruments caused by medical injury; transverse injuries are mostly caused by gunshot wounds, explosive injuries and cuts, which are open injuries; and blunt contusions are caused by direct or indirect violence such as high falls, car accidents, pelvic fractures and crushing and rough sexual intercourse, which are mostly closed injuries, and severe pelvic fractures can cause urethral lacerations. According to the anatomical relationship, the male urethra is divided into two major parts, the anterior urethra and the posterior urethra, with the anterior urethra including the urethral bulb and the penile part, and the posterior urethra including the prostate part and the membrane part, using the urogenital diaphragm as the boundary. The site, degree and treatment principles of urethral injury are basically determined according to the anatomical relationship between the anterior and posterior urethra. The urethra will undergo a series of pathological changes from injury to healing, which can be divided into three pathological stages according to the different histological characteristics of different stages, namely the injury stage, inflammation stage and stenosis stage. I. Posterior urethral injury Posterior urethral injury mostly combined with pelvic fractures (more than 90%), commonly in crush injuries such as car accidents and landslides. As a result of pelvic fractures causing deformation of the pelvic floor structure, the prostate pelvic floor attachment and pubic prostatic ligaments are sharply stretched or even torn, so that the prostate is suddenly displaced upward, through which the urethral membrane and prostate can occur lacerations, the prostate tip is violently displaced or the urogenital diaphragm is displaced can produce strong shear forces, causing complete rupture of the posterior urethra in severe cases. After the rupture of the posterior urethra, urine extravasation can accumulate in the retropubic space and around the bladder. Clinical symptoms and signs】 Pain in the lower abdomen and difficulty in urination are common symptoms of posterior urethral injury. After a rupture or tear of the urethra, interruption of urethral continuity or clot obstruction can cause urinary retention, resulting in extreme bladder filling and increased painful symptoms. Bleeding from the urethra is an independent and most important sign of urethral injury, suggesting that urography should be performed as soon as possible to clarify the diagnosis. In the case of pelvic fracture, a careful physical examination should be performed. Loose collapse of the pubic symphysis, hematoma and bruising in the perineum all suggest a possible combined urethral injury. If the prostate is fixed by rectal palpation, it often indicates that the pubic prostatic ligament is intact and the posterior urethra will not be completely ruptured in such cases. However, sometimes a tightly packed pelvic floor hematoma can be mistaken for fixed prostate tissue on palpation, so rectal palpation has a certain subjective error rate and cannot be relied on alone to clarify the extent of urethral injury. The pelvic plain film can clarify the site and extent of pelvic fracture. At present, retrograde urography or cystourethrography should be used as the first auxiliary examination for the diagnosis of urethral injury, applying 20-30 ml of 15%-20% contrast agent under strict aseptic conditions. If contrast spillage is found, urethral injury can be diagnosed, and the extent and location of urethral injury can be clarified according to the extent and location of contrast spillage. If the contrast agent passes through the injury site into the posterior urethra or bladder to be visualized, it suggests a partial urethral rupture; if there is a large spillage of contrast agent and the posterior urethra and bladder are not visualized, it suggests a complete urethral rupture. Retrograde urography has also been discouraged as the first choice on the grounds that stimulation of the contrast medium and access to the surrounding tissues may be one of the reasons for the formation of urethral strictures later in the injury. Excretory urography in the case of posterior urethral rupture may show an elevated bladder position with a teardrop presentation. It has been suggested that excretory urography should be the first choice for urethral injury, followed by retrograde urography when the site and extent of urethral injury cannot be determined. Catheterization and cystoscopy should not be performed without clarification of the site and extent of posterior urethral injury; invasive manipulation may aggravate hematoma, infection, and other side injuries. Inappropriate catheterization may aggravate incomplete urethral lacerations and may lead to complete urethral rupture in severe cases. In addition, it may also increase the chance of infection in the retropubic space and around the bladder. Differential diagnosis】 It is mainly distinguished from bladder rupture, which can also occur with lower abdominal pain, dyspareunia, anuria and other symptoms, but the bladder area is empty without filling on examination, and there is no displacement of the prostate gland on rectal finger examination. In case of simple bladder rupture, the catheter is inserted smoothly, but there is no urine or only a little hematuria is induced, the amount of injected experimental reflux fluid is small or absent, and cystourethrography can show the spillage of contrast agent at the bladder rupture. 【Treatment】 1, systemic treatment: prevention and treatment of shock, immediate anti-infection, blood volume supplementation and combined injury treatment, acute urinary retention occurred inoperable, temporary suprapubic cystostomy to drain urine, and then dispose of urethral injury after the condition is stabilized. 2, local treatment: posterior urethral rupture injury treatment options are more, there is still some debate, but regardless of the view, should be based on the time, location and medical conditions of the patient’s injury to perform treatment, the principle of treatment should be to avoid near and long-term complications under the premise of restoring the original anatomical and physiological structure and function of the urethra, to achieve the best therapeutic effect. The current mainstream treatment options can be broadly divided into the following: (1) closed posterior urethral blunt contusion can be treated with indwelling catheterization, after smooth placement of the balloon catheter, the catheter is left in place for 3 weeks, and a little traction is beneficial to urethral alignment. (2) Posterior urethral injuries are often combined with pelvic fractures and other organ injuries such as bladder and rectum, so bleeding shock and other important organ combined injuries caused by pelvic fractures should be prevented and treated first, and secondary infections should be prevented and treated. If the vital signs are not stable, there are serious combined injuries to important organs, and there is urinary retention and extravasation at the same time, and if the trial of catheterization fails, suprapubic cystostomy should be performed promptly, and after the condition is stabilized, second-stage urethral repair should be performed. (3) In the case of complete posterior urethral rupture, stable pelvic fracture, and without serious hemorrhagic shock and rectal injury, suprapubic cystostomy + urethral rendezvous is feasible within 72 hours after injury, i.e., during the urethral trauma stage, and traction is appropriate for 5-7 days after surgery, with traction force of 300-750g, and the traction angle with the longitudinal axis of the torso at 45 degrees to the longitudinal axis of the torso. The catheter should be left in place for 3-4 weeks and a cystourethrogram should be performed at the time of extubation, and the necessary urethral dilatation should be performed depending on the degree of stricture. (4) Some scholars advocate early emergency urethral anastomosis to restore the anatomical alignment of the severed urethra, which can effectively prevent the occurrence of traumatic urethral stricture, but emergency urethral anastomosis is difficult and demanding, and in most cases it is difficult to achieve significant results. Complications】 1.Pelvic fracture: the pelvic fracture site of combined posterior urethral injury is mostly in the pubic bone and sit bones, without displacement or displacement is not obvious, no special treatment is necessary, and the patient can get out of bed for 3-6 weeks; if the fracture displacement is obvious, the pelvis is unstable, combined with multiple fractures or comminuted fractures, joint surgery should be performed in cooperation with orthopedic surgeons. 2. Pelvic hemorrhage: Patients are often in shock at the time of consultation, and should be given blood transfusion, fluid replacement and other rescue anti-shock treatment to maintain life. If pelvic bleeding is encountered during posterior urethral repair, sutures, bone wax closure, filling hemostasis and other methods can be applied, and arterial embolization can also be applied to treat traumatic pelvic bleeding. 3, posterior urethral injury complicating rectal injury: early repair can be done immediately, and temporary sigmoid colostomy can be made to reduce the chance of fecal contamination, which is beneficial to the healing of rectal injury. After 3 months of inflammation control, urethral repair will be performed. In case of urorectal fistula, repair should be performed after 3-6 months. Prognosis] The prognosis of posterior urethral injury is very good if complications can be avoided or controlled. The more common sequelae of posterior urethral injury with a poor prognosis are mainly urinary tract infection, urethral stricture and sexual dysfunction. Urinary tract infections can be effectively controlled and treated with appropriate management. Urethral stricture is a major complication in the late stage, and treatment can be based on the degree and location of the stricture by choosing methods such as urethral dilatation or reanastomosis. Different degrees of impotence can occur within a few months or longer after pelvic fracture combined with urethral injury. If symptoms do not recover after 2 years of occurrence, the injury can be considered permanent and treatment such as prosthetic implantation is feasible to improve the quality of life. Second, the anterior urethral injury Male anterior urethral injury is mostly caused by closed perineal injury caused by riding across the injury or direct violent blow to the perineum, the spongy body fracture during sex, masturbation, self-harm of psychiatric patients is also the cause of closed anterior urethral injury. Repeated catheterization and urethral cystoscopy can also cause urethral injury. Clinical manifestations and signs] Blood spilling or dripping from the external urethral opening of the injury is the most common symptom of anterior urethral injury. In addition, the injury is accompanied by radiating pain in the perineum, scrotal and penile skin swelling, petechiae and hematoma due to urethral bleeding or urinary extravasation, and complete urethral rupture can lead to difficulty in urination and urinary retention, but the presence of difficulty in urination and urinary retention is not necessarily a diagnosis of complete urethral rupture, because the local pain, edema and external sphincter spasm caused by the injury can also lead to the above symptoms, and further examination is required to Further examination is required to determine the severity of the injury. In the case of urethral bulb injury, blood and urine first leak into the superficial perineal pouch surrounded by the superficial perineal fascia, causing scrotal swelling. If it continues to develop, it can spread along the superficial perineal fascia, causing swelling of the perineum and penis, and can spread deeper along the superficial fascia of the abdominal wall and upward to the abdominal wall, but is limited at the inguinal and deltoid ligaments. In case of rupture of the penile part of the urethra, if the penile fascia is intact and urine extravasates to the penile part, it may show swelling and bruising of the penis. If the penile fascia ruptures, urine enters the scrotum and perineum and spreads upward to the subcutaneous lower abdomen, and the extent of urinary extravasation is the same as that of ball injury. [Auxiliary examination] Diagnostic catheterization can check the integrity and continuity of the urethra. A soft catheter is appropriate, and a metal catheter is contraindicated. If the insertion is smooth and the urine is clear, the injury is slight and the catheter should be kept to drain the urine and support the urethra, if it cannot be inserted, it suggests a complete urethral rupture and should not be forcibly inserted at this time. Retrograde urethrography or cystourethrography can show the location of the urethral break, and contrast spillage suggests disruption of urethral continuity and can distinguish the site and extent of injury. This operation may cause retrograde infection and needs to be performed with strict aseptic conditions and caution. Differential diagnosis】 It is easy to diagnose anterior urethral injury with a clear history, symptoms and accurate judgment of the site of urinary extravasation. The site of anterior and posterior urethral injury must be clarified for further treatment. Treatment】 1, systemic treatment: prevention and treatment of shock, immediate anti-infection, blood volume and combined injury treatment, the occurrence of acute urinary retention can not be operated, temporary suprapubic cystostomy to drain urine, to be stable before disposal of urethral injury. 2, local treatment (1) treatment of anterior urethral contusion: minor injury to the anterior urethra, not much bleeding, smooth urination, can be treated under observation. If the pain or edema causes difficulty in urination or even urinary retention, a urethral tube can be inserted and left in place for 1 week, while strengthening bladder irrigation and giving anti-infective drugs to prevent infection. (2) Treatment of incomplete rupture of the anterior urethra: If the rupture is mild, there is no obvious urinary extravasation and hematoma around the urethra, and the catheter is inserted smoothly with clear or light red urine, the catheter can be left in place for 2 weeks and then removed, and later urethral dilatation can be performed according to the situation. At the same time, anti-infective drugs and estrogen therapy are given, and surgery is not necessary. (3) Treatment of complete anterior urethral rupture: If the catheter cannot be inserted, the liquid bright red blood is exported, and the scrotum is obviously hematoma and urinary extravasation, emergency urethral repair or end-to-end urethral anastomosis is required, along with complete removal of hemostasis and removal of hematoma, and drainage strips are left in place for continuous drainage after surgery. Tight alignment during surgery can satisfactorily restore the anatomical continuity of the urethra, and urethral dilatation is rarely required after healing. Complication management】 1. Urinary extravasation: If urinary extravasation is serious, multiple incisions should be made at the site of urinary extravasation as early as possible and a porous rubber tube should be left for drainage. If necessary, suprapubic cystostomy should be performed, and then urethral repair should be performed after 3 months. 2.Urethral stricture: When urethral stricture occurs in late stage, the corresponding treatment can be chosen according to the degree and location of urethral stricture. 3, urinary fistula: urinary extravasation is not drained in time, abscess can be formed around the urethra after infection, abscess penetration to form urinary fistula, and poor urinary flow during stricture can also cause urinary fistula. The treatment should be removed or scratched fistula when the urethral stricture is lifted.