MRI plays an ancillary role in the initial imaging evaluation of penetrating lower urinary tract injury that is due to the difficulty of monitoring a seriously injured patient in a strong magnetic field. MRI has been described for follow-up evaluation of urethral injury as an adjunctive tool for assessing complex urethral anatomic derangements [20,21]. Radiography Intravenous Urography There is no recent relevant literature regarding the use of an IV urogram in the evaluation of penetrating trauma to the lower urinary tract. An IV urogram is typically inadequate for evaluating the bladder and urethra after penetrating trauma because the contrast material within the bladder is diluted and the resting intravesical pressure is simply too low to demonstrate a small tear [15]. Fluoroscopy Retrograde Urethrography Patients with penetrating trauma to the penis should undergo RUG as the primary diagnostic procedure because of concern for injury of the anterior urethra [22]. Because posterior urethral injuries can also result from penetrating trauma to the pelvis and perineum, and are associated with pelvic fractures, a RUG should be performed before inserting a catheter [7,10,18]. In the past, a diagnosis of acute urethral injury often was based loosely on the clinical triad of 1) blood at the urethral meatus, 2) inability of the patient to void, and 3) a palpable urinary bladder. An inability to pass the catheter into the bladder was also considered diagnostic of a posterior urethral injury. It is now well established, however, that diagnostic catheterization is to be avoided, as it may convert a partial injury into a complete disruption [2,22]. In female patients with a suprapubic catheter in place, a descending or voiding urethrography may be sufficient; a RUG may also be performed with a small-caliber catheter pressed against, or slightly beyond, the urethral meatus [9].
Penetrating Trauma Lower Abdomen and Pelvis. MRI plays an ancillary role in the initial imaging evaluation of penetrating lower urinary tract injury that is due to the difficulty of monitoring a seriously injured patient in a strong magnetic field. MRI has been described for follow-up evaluation of urethral injury as an adjunctive tool for assessing complex urethral anatomic derangements [20,21]. Radiography Intravenous Urography There is no recent relevant literature regarding the use of an IV urogram in the evaluation of penetrating trauma to the lower urinary tract. An IV urogram is typically inadequate for evaluating the bladder and urethra after penetrating trauma because the contrast material within the bladder is diluted and the resting intravesical pressure is simply too low to demonstrate a small tear [15]. Fluoroscopy Retrograde Urethrography Patients with penetrating trauma to the penis should undergo RUG as the primary diagnostic procedure because of concern for injury of the anterior urethra [22]. Because posterior urethral injuries can also result from penetrating trauma to the pelvis and perineum, and are associated with pelvic fractures, a RUG should be performed before inserting a catheter [7,10,18]. In the past, a diagnosis of acute urethral injury often was based loosely on the clinical triad of 1) blood at the urethral meatus, 2) inability of the patient to void, and 3) a palpable urinary bladder. An inability to pass the catheter into the bladder was also considered diagnostic of a posterior urethral injury. It is now well established, however, that diagnostic catheterization is to be avoided, as it may convert a partial injury into a complete disruption [2,22]. In female patients with a suprapubic catheter in place, a descending or voiding urethrography may be sufficient; a RUG may also be performed with a small-caliber catheter pressed against, or slightly beyond, the urethral meatus [9].