If a patient with a suspected fracture of the pelvis has some bleeding from the urethra and is unable to pass urine -

The urethral injury is common with pelvic fracture and an inability to void and blood at the external meatus are the classical signs of urethral rupture. No attempt should be made to pass a catheter, as this could convert a partial to a complete tear of the urethra. If the urethral injury is suspected, this can be diagnosed more accurately and more safely by retrograde urethrography. If there is a complete urethral tear, primary realignment of the urethra may be achieved by performing suprapubic cystostomy, evacuating the pelvic hematoma and then threading a catheter across the injury to drain the bladder. If there is an incomplete tear, the insertion of a suprapubic catheter as a formal procedure is all that is required. Around half, all incomplete tears will heal.