Multi-modality imaging of the leaking ureter: why does detection of traumatic and iatrogenic ureteral injuries remain a challenge?

Ureteral injuries are uncommon in trauma patients, accounting for fewer than 1% of all injuries to the urinary tract. These uncommon, yet problematic, injuries can often be overlooked in the standard search pattern on abdominal and pelvic multi-detector CT (MDCT) images, as radiologists focus on more immediate life-threatening injuries. However, early diagnosis and management are vital to reduce potential morbidity. If there is a high clinical index of suspicion for ureteral injuries with penetrating or blunt trauma, or if there is suspected iatrogenic ureteral injury, delayed-phase/urographic-phase MDCT images are essential for confirming the diagnosis. Moreover, making the distinction between partial and complete ureteral transection is critical, as it will guide management. The aim of this pictorial review is to overview the key imaging findings in blunt and penetrating traumatic and iatrogenic injuries of the ureter, as well as to discuss the advantages and disadvantages of different imaging modalities for accurately and rapidly establishing or excluding the diagnosis of ureteral injuries, with an emphasis on MDCT. The potential causes of missed ureteral injuries will also be discussed.