5. TRAUMATIC UROLOGICAL EMERGENCIES 89
FIGURE 5.18. This is a computed tomography (CT) scan of the same case as in Figure 5.16 (open-book fracture). The degree of displacement of bone fragments looks much worse on CT.
fractured bones will have moved a greater distance during the process of fracturing. With this in mind, it is not difficult to imagine that soft tissues might have been injured. In the case of the bladder; for example, this occurs either by shearing forces that fracture the bone and literally tear the bladder apart by virtue of its fascial attachments to the pelvis or as a consequence of a direct scissors like action of sharp edges of the fractured bone. The bladder's location immediately behind the pubic bone makes it a vulnerable target, and whenever a patient with a pelvic fracture is seen, you should assume they have a bladder and/or urethral injury until proven otherwise. Not surprisingly, thin-walled pelvic veins can be torn by these same shearing or cutting forces.
Bladder Injuries Associated with Pelvic Fractures
Approximately 10% of males with a pelvic fracture and a slightly lower percentage of females will have an associated bladder injury. Of those bladder ruptures that are due to external blunt trauma
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(as opposed to perforation during, for example, bladder tumour resection), approximately 85% are associated with a pelvic fracture, 10% with a fracture of the proximal femur, and 5% have no associated bony injury, the force applied to the abdomen in these latter cases having been sufficient to burst the bladder, but not to fracture any bones (e.g., the patient intoxicated by alcohol whose full bladder is already under tension and therefore ruptures when he falls down stairs or is hit by a car). Bladder injuries are often associated with anteroposterior pelvic compression fractures (rather than lateral compression fractures) (Zingg et al. 1990). Approximately 60% of traumatic blunt bladder ruptures are extraperitoneal, 30% are intraperitoneal, and 10% are a combination of extraperitoneal and intraperitoneal (Peters 1989).