Where a patient is transferred immediately to the operating theatre without having had a CT scan and a retroperitoneal haematoma is found, a single-shot abdominal x-ray taken 10 minutes after contrast administration (2mL/kg of contrast) can be used to establish whether or not there is a renal injury (Morey et al. 1999). If the patient is hypotensive, take the image at between 20 and 30 minutes, so that there has been time for excretion of a sufficient quantity of contrast to allow opacification of the kidney. On-table IVU can also be very useful in determining the presence of a normally functioning contralateral kidney where the injury to the ipsilateral kidney is likely to necessitate a nephrectonry In the San Francisco General Hospital experience a single-shot IVU, in many cases, has provided an image
Grade I Grade II Grade III Grade IV Grade V
Figure 5^ American Association for the Surgery of Trauma Organ mjiiry Severity Scale for renal injuries
5. TRAUMATIC UROLOGICAL EMERGENCIES 59
of sufficient quality to allow accurate intraoperative decision making to be made, and in approximately 30% of cases the intraoperative IVU findings obviated the need for renal exploration.
In general terms, renal exploration is indicated for:
Persistent bleeding (persistent tachycardia and/or hypotension failing to respond to appropriate fluid and blood replacement
Expanding perirenal haematoma (again the patient will show signs of continued bleeding)
Pulsatile perirenal haematoma
The categorisation of renal injuries into blunt and penetrating types determines the likely need to explore the kidney to stop bleeding and/or repair the renal injury. Over 95% of blunt injuries can be managed conservatively and, at least in centres where a high frequency of renal injuries is seen, a substantial proportion of penetrating injuries can be managed without renal exploration. In the San Francisco General Hospital, a centre with an international reputation for the management of renal injuries, approximately 50% of renal stab injuries and 25% of renal gunshot wounds can be managed nonoperatively.