type I: stretching of the posterior urethra due to disruption of puboprostatic ligaments, despite the urethra being intact.
type II: urethral injury above the urogenital diaphragm.
type III: injury to the membranous urethra, extending into the proximal bulbous urethra.
type IV: bladder base injury involving bladder neck extending into the proximal urethra.
type IVa: bladder base injury without contacting bladder neck (which cannot be separated from type IV radiologically).
type V: anterior urethral injury.