Suspect a renal injury, and arrange renal imaging, in trauma cases with:
56 J. REYNARD
FIGURE 5.1. Computed tomography urogram (CTU) of blunt trauma to the right kidney following a fall onto the flank.
■ Macroscopic haematuria
■ Penetrating chest, flank, and abdominal wounds (knives, bullets)
■ Microscopic [>5 red blood cells (RBCs) per high powered field] or dipstick haematuria in a hypotensive patient (hypotension is defined as a systolic blood pressure of <90mmHg recorded at any time since the injury) (Mee et al. 1989, Nicolaisen et al. 1985)
■ A history of a rapid acceleration or deceleration
■ Any child with microscopic or dipstick haematuria who has sustained trauma
Haematuria is not always present in cases of renal injury, nor does the degree of haematuria correlate with the degree of renal injury. In particular, haematuria may be absent in renal vascular injuries and those where the ureter or pelviureteric junction (PUJ) has been avulsed.
Adult patients with a history of blunt trauma and microscopic or dipstick haematuria need not have their kidneys imaged as long as there is no history of acceleration/deceleration and no
5. TRAUMATIC UROLOGICAL EMERGENCIES 57
shock, since the chances of a significant injury being found are <0.2% (Miller and McAninch 1995).
What Imaging Study?
The intravenous urogram (IVU) has been replaced by the contrast-enhanced CT scan as the imaging study of choice in patients with suspected renal trauma. It provides clear definition of the injury, allowing injuries to the parenchyma and collecting system to be accurately graded (staged). The IVU is not as accurate as CT. The grade of injury provides a guide to subsequent management. Spiral CT (performed either without contrast or within a few minutes of contrast administration) does not allow accurate staging, because contrast will not yet have had time to reach the parenchyma or collecting system. A repeat CT scan 10 or 15 minutes after contrast administration will demonstrate parenchymal or collecting system injuries accurately.