Since then, CT cystography has become the first-line evaluation for bladder injury in the acute trauma setting [4]. This technique refers to the retrograde instillation of a minimum of 350 cc of diluted contrast media into the bladder, followed by axial and coronal CT images of the pelvis [6,14]. Unlike conventional cystography, no postdrainage CT images are needed. In a study that included patients who sustained blunt and penetrating trauma, there was 100% sensitivity and 99% specificity for intraperitoneal bladder rupture; additionally, the specific site of bladder dome injury was found in 4 of the 18 patients and was identified only with multiplanar reconstructed images [14]. An advantage of CT cystography is the ability to diagnose injuries to other pelvic viscera, osseous structures, and vasculature. Contrast-enhanced CT with excretory phase imaging is not a reliable means to diagnose bladder rupture, even after a urethral catheter has been inserted and clamped [2,15,16]. Excretory phase imaging is defined as antegrade filling of the urinary bladder that is due to excretion of intravenous (IV) contrast material through the kidneys. Although intraperitoneal and extraperitoneal fluid can be detected during excretory phase CT, the etiology of the fluid cannot be determined because the bladder is usually inadequately distended to cause extravasation through a bladder laceration or perforation. Although the absence of pelvic fluid is strong evidence against a bladder rupture, a negative study does not exclude bladder injury [17]. The literature suggests that both conventional and CT cystography are equivalent, with physician preference and diagnostic protocols generally defining the method used [2,13,18]. Although CT is not the technique of choice for urethral injuries, it is performed so frequently that urethral injuries are inevitably identified when performed for pelvic trauma.
Penetrating Trauma Lower Abdomen and Pelvis. Since then, CT cystography has become the first-line evaluation for bladder injury in the acute trauma setting [4]. This technique refers to the retrograde instillation of a minimum of 350 cc of diluted contrast media into the bladder, followed by axial and coronal CT images of the pelvis [6,14]. Unlike conventional cystography, no postdrainage CT images are needed. In a study that included patients who sustained blunt and penetrating trauma, there was 100% sensitivity and 99% specificity for intraperitoneal bladder rupture; additionally, the specific site of bladder dome injury was found in 4 of the 18 patients and was identified only with multiplanar reconstructed images [14]. An advantage of CT cystography is the ability to diagnose injuries to other pelvic viscera, osseous structures, and vasculature. Contrast-enhanced CT with excretory phase imaging is not a reliable means to diagnose bladder rupture, even after a urethral catheter has been inserted and clamped [2,15,16]. Excretory phase imaging is defined as antegrade filling of the urinary bladder that is due to excretion of intravenous (IV) contrast material through the kidneys. Although intraperitoneal and extraperitoneal fluid can be detected during excretory phase CT, the etiology of the fluid cannot be determined because the bladder is usually inadequately distended to cause extravasation through a bladder laceration or perforation. Although the absence of pelvic fluid is strong evidence against a bladder rupture, a negative study does not exclude bladder injury [17]. The literature suggests that both conventional and CT cystography are equivalent, with physician preference and diagnostic protocols generally defining the method used [2,13,18]. Although CT is not the technique of choice for urethral injuries, it is performed so frequently that urethral injuries are inevitably identified when performed for pelvic trauma.