Problems Imaging the Bladder in Patients with Urethral Rupture
Ten percent to 20% of patients with a posterior urethral rupture also have a bladder rupture (Cass et al. 1984), and 5% to 10% of patients with a pelvic fracture and bladder rupture also have a posterior urethral rupture (Cass and Luxenberg 1987). This presents a dilemma because the urethral rupture makes it difficult, radiologically, to diagnose a bladder injury. A catheter cannot be negotiated past the urethral rupture into the bladder to allow a cystogram to be done, and contrast administered during the ure-throgram may not reach the bladder in sufficient quantities to diagnose a bladder rupture, or it may extravasate around the
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bladder and obscure a perforation. A CT cystogram can be done by taking delayed films in the CT scanner, relying on the intravenously administered contrast to define the bladder. However, as discussed above, these images are not as accurate at diagnosing or excluding a bladder rupture when compared with instillation of contrast into the bladder by the retrograde route (retrograde cystography). Furthermore, these patients are usually very unwell and are often transferred rapidly to the operating room for treatment of the pelvic fracture and associated injuries. In this situation there often simply isn't time to wait for contrast administered intravenously to work its way into the bladder to allow a CT cystogram to be done.
Where a cystogram cannot be done because of a urethral rupture, the patient should be transferred to the operating theatre so that a suprapubic catheter can be inserted by a formal open approach—an open suprapubic cystostomy (if there is a urethral injury this will usually be left alone and definitive repair carried out at a later date when the patient's condition is stable). By making the incision in the bladder somewhat larger than is necessary for placement of a suprapubic catheter, the bladder may be inspected to see if there is a perforation, and if so, it can be repaired. Rarely, fragments of bone may be seen poking through the wall of the bladder, and these can be removed with bone forceps before the bladder is repaired. It is better to open the bladder and find that it has not been injured than to allow urine from a missed perforation to pour into the pelvis of a patient with a large haematoma and fractured bone, with the obvious risk of subsequent pelvic sepsis.