UROGENITAL TRAUMA

Blunt Renal Trauma: Comparison of Contrast-Enhanced CT and Angiographic Findings and the Usefulness of Transcatheter Arterial Embolization
Kitase M, Mizutani M, Tomita H, Kono T, Sugie C, Shibamoto Y
Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
Vasa. 2007; 36: 108-13

• Background: The purpose of this study was to evaluate the role of contrast-enhanced CT and the usefulness of superselective embolization therapy in the management of arterial damage in patients with severe blunt renal trauma.
• Patients and Methods: Nine cases of severe renal trauma were evaluated. In all cases, we compared contrast-enhanced CT findings with angiographic findings, and performed transcatheter arterial embolization (TAE) in six of them with microcoils and gelatin sponge particles. Morphological changes in the kidney and site of infarction after TAE were evaluated on follow-up CT Chronological changes in blood biochemistry findings after injury, degree of anemia and renal function were investigated. Adverse effects or complications such as duration of hematuria, fever, abdominal pain, renovascular hypertension and abscess formation were also evaluated.
• Results: The CT finding of extravasation was a reliable sign of active bleeding and useful for determining the indication of TAE. In all cases, bleeding was effectively controlled with superselective embolization. There was minimal procedure-related loss of renal tissue. None of the patients developed abscess, hypertension or other complications.
• Conclusions: In blunt renal injury, contrast-enhanced CT was useful for diagnosing arterial hemorrhage. Arterial bleeding may produce massive hematoma and TAE was a useful treatment for such cases. By using selective TAE for a bleeding artery, it was possible to minimize renal parenchymal damage, with complications of TAE rarely seen.
  
  
• Editorial Comment
  The use of transcatheeter arterial embolization is a useful tool when managing renal traumatic injuries. There are typically two situations where embolization is needed, in the acute setting bleed and in a delayed bleed (usually 10-14 days after initial injury). In the acute setting, on the arterial phase images of the CT there is a characteristic “blush” (as in splenic trauma), which suggests a significant arterial injury. While we speak of the retroperitoneum as a confined space that can hold up to 4 to 8 units of blood, the tamponade effect is typically applicable to significant venous bleeding and not arterial injuries. Most major trauma centers are lucky to have a skilled vascular and intervential radiologist who can perform a super selective branch of the renal artery embolization. In the delayed setting, bleeding usually occurs 7 to 14 days after the initial injury. It is at this time that the hematoma starts to lyse and thus releases the tamponade effect. It is also the time it usually takes for a pseudoaneurysm to occur. While AAST Grade V real injuries are life threatening arterial injuries that warrant exploration, all lesser degrees of renal injuries usually do not cause hemodynamic instability and can thus be managed expectantly. With lesser degree renal injuries, the cause for hypotension is typically from associated intra-abdominal injuries and not the kidney injury itself. The reasons for such hemodynamic stability is that fracture lines in the shattered kidney are typically radial in fashion and parallel to the interlobar arteries, and not through them. This is why the kidney can often seem to be broken into multiple pieces yet the parenchyma still be bright, with intravenous contrast on the nephrographic phase images. As to the infarcted parenchyma after embolization, when the segment of parenchyma is large (usually more than 25%) the patient will often have “post-infraction” spiking fevers and a white count for 2 to 3 days, which resolve spontaneously. I have had the same experience as the authors as to complications after embolization. I have not seen a single case of abscess or sustained hypertension. While episodes of transient hypertension are not uncommon, prolonged hypertension is exceedingly rare (less then 1% overall).

Dr. Steven B. Brandes
Associate Professor, Division of Urologic Surgery
Washington University in St. Louis
St. Louis, Missouri, USA