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BackTable / VI / Article
Renal Trauma: Biopsy Risks, Imaging Techniques & Treatment Options
Sai Govindu • Updated Jun 30, 2023 • 97 hits
Renal interventions, particularly renal biopsy and renal embolization, are common procedures for interventional radiology. However, Dr. Christopher Beck and Dr. Nima Kokabi urge their colleagues, and especially younger IR attendings, to exercise caution when approaching routine renal interventions, especially renal biopsy. Biopsy, particularly in the context of renal failure or certain conditions like lupus, carries substantial bleeding risks, and is a common cause of renal trauma. In the case of trauma, further treatment by IR may not always be the best option. A thorough workup of patient symptoms, and imaging methods such as two-phase arterial and venous CT scans, can help determine if a renal trauma patient is a suitable candidate for renal embolization or partial nephrectomy. Learn more about how Dr. Kokabi and Dr. Beck approach renal trauma and how they decide which treatment is most appropriate.
The BackTable Brief
• Renal traumas requiring IR intervention are often iatrogenic, arising from inadequately targeted renal biopsies. Biopsies performed in an office setting without sufficient imaging are particularly prone to causing kidney injuries.
• Renal biopsies, especially in the context of renal failure or specific conditions like lupus, carry a significant risk of bleeding and are deemed more hazardous than other solid organ biopsies. Clinicians should be cognizant of the potential risks associated with renal biopsies, ensuring meticulous evaluation of patients, including monitoring blood pressure and overall health status.
• The decision to conduct partial nephrectomy or embolization depends largely on the nature and severity of the trauma, with a lower threshold for surgery in cases of penetrating trauma. Small pseudoaneurysms in stable patients may not necessitate immediate intervention; a close monitoring strategy could be more beneficial.
• Two-phase arterial and venous CT scans are crucial for diagnosing renal bleeds and assessing the viability of embolization procedures.
Table of Contents
(1) Kidney Biopsy: A Common Cause of Renal Trauma
(2) Renal Trauma Imaging, Diagnosis & Management Options
Kidney Biopsy: A Common Cause of Renal Trauma
Errors in kidney biopsy procedures can lead to renal trauma and the need for further intervention, notably those resulting from non-targeted renal biopsies performed in outpatient settings without adequate imaging. A lack of adherence to recommended biopsy guidelines—such as targeting the lower pole and avoiding areas of high vascularity—contributes to this predicament. Contrary to common perception, renal biopsies, especially those performed in the context of renal failure or conditions like lupus, are not trivial procedures, but rather present significant bleeding risks and can, in rare instances, prove fatal. Clinical vigilance is imperative in performing kidney biopsies, considering variables such as the patient's health status and blood pressure, to mitigate associated risks and ensure patient safety.
[Chris Beck MD]
Moving out of logistics, let's dig in a little bit into kidney injury specifically. We were joking offline, like a lot of alley-oops from people who do kidney biopsies. You were joking about interventional nephrology. Let's talk about just kidney injury in general. In your practice, what was the most common setting for IR consults for kidney injury?
[Nima Kokabi MD]
I was half joking, you know that behind every joke there is a pinch or lies of truth. To be honest with you the majority of the traumas that would require intervention, at least in my experience at Emory, and I've heard from other colleagues of mine around the country that the majority of kidney traumas that require intervention by IR or are iatrogenic from non-targeted renal biopsies are done in the office setting, a lot of times without appropriate imaging. Nowadays, more and more nephrologists have access to ultrasound at least doing these renal biopsies, but even in those cases, I feel that the mantra that we follow for biopsies in terms of being in the lower pole, trying to avoid the areas of high vascularity in the kidneys, those are generally not followed unfortunately by a nephrologist. That is why a lot of these biopsies are, at least anecdotally, the number of traumatic iatrogenic cases that we get from nephrology biopsies are higher than our own.
That is not to say, we don't actually cause renal bleeds, meaning IR doesn't cause renal bleeds, suppose biopsies, of course. In my opinion, it's actually one of the more scary biopsies to do, particularly in the setting of renal failure, which is the majority of these cases, particularly, at least in my experience in the setting of lupus. Those patients in my experience have bled the most at least.
It is a very humbling procedure to do. People think it's an easy procedure, that it's a cheap shot, but I've seen people die from it, to be honest with you.
[Chris Beck MD]
I totally agree with you on that, in that when I think about solid organ biopsies, like outside of the spleen Give me a liver or lung any day, but starting a kidney sometimes after two or three o'clock, especially on in-house patients, I'm always like, "Oh, where are they coming from? What's their status? What's their blood pressure?" I think there's a lot that goes into it.
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Renal Trauma Imaging, Diagnosis & Management Options
The choice of intervention is largely determined by the nature and severity of the trauma, as well as the clinical presentation of the patient. While partial nephrectomies and embolization are common responses to blunt renal trauma, the threshold for surgery is lower in cases of penetrating trauma. Cross-sectional imaging, particularly CT scans in arterial and venous phases, plays a pivotal role in diagnosing renal bleeds and assessing the feasibility of embolization. Small pseudoaneurysms in stable patients may not warrant immediate intervention. Instead, a watchful waiting approach coupled with close monitoring can be adopted, emphasizing the delicate balance between action and restraint in renal trauma management.
[Chris Beck MD]
Not to dwell too much on solid kidney biopsies, but outside of just kidney biopsies, did you guys treat a fair amount for partial nephrectomies, or just either penetrating, or blunt trauma?
[Nima Kokabi MD]
Partial nephrectomy for sure, as well as more blunt trauma than penetrating. I feel that when it's involving the kidney, again, I don't have the data to back it up, but I feel that if there is a penetrating trauma involving the kidney, probably the threshold is much lower to go to the operating room.
[Chris Beck MD]
As far as diagnosis goes, you suspect a renal bleed. Did all of those patients move on to cross-sectional imaging in some way, or CTA is absolutely necessary, or with a high enough pretest probability, would you take some patients to the angio straightaway?
[Nima Kokabi MD]
Generally, for renal, we get a CT beforehand. In the past three years, we actually migrated from having a single-phase, PAN scan of the chest, abdomen, and pelvis in mostly the venous phase to actually having a two-phase arterial and venous phase, which actually increases the pretest probability of a renal bleed significantly. Again, not backed up by data, but at least anecdotally.
Generally, for those patients, we do a CT beforehand. The ones that we generally go to embolization without a CT are the pelvic traumas. If they're in shock, a lot of times there's just no time to chat in much words, so we go straight to angio. They know basically based on an x-ray that there is an open book pelvic fracture, and then there's no other, at least visual trauma to the abdomen, so they usually ask us to do those without doing the CT scan.
[Chris Beck MD]
Sure. Are those guys using the AAST Renal Injury Scale? Is that something that was very much built into the algorithm?
[Nima Kokabi MD]
Recently, in the past two to three years, we had an emergency radiology department at Emory that was working very closely with the trauma surgeons. Because of that, they actually made sure that on all reports for solid organ injuries, there is a grading scale that is reported.
[Chris Beck MD]
If any times like if active extravasation or pseudoaneurysm was identified, was that almost an automatic call to IR?
[Nima Kokabi MD]
Yes, it was.
[Chris Beck MD]
Were there any situations where the kidney injuries, where it just looks like an unexploded kidney, were those patients move on to nephrectomy, or?
[Nima Kokabi MD]
Yes, particularly if you do a two-phase and you don't see any enhancement. If it is a completely evolved kidney, you don't see any enhancement of the parenchymal more delayed phase, I think those are very good scenarios that you should not intervene on because there's basically nothing. Either the artery is completely transected, or maybe the artery and vein are both transected, so in the interest of not wasting time, those patients should go to the operating room directly.
[Chris Beck MD]
Was the urology service at Emory, I guess it would be urology that would take those patients there who are not trauma?
[Nima Kokabi MD]
Interestingly, it's trauma that takes care of those patients, at least at Grady.
[Chris Beck MD]
The trauma team and trauma surgeons were pretty aggressive, very reasonable, and willing to helping people out?
[Nima Kokabi MD]
They're in a good relationship with IR. Rarely did we had disagreement in terms of how to manage a patient.
[Chris Beck MD]
Can you paint any scenarios, especially for younger IR docs. I think it's sometimes easy to know when to take a patient to angio and it's easy to know when, "Hey, this is not an IR issue, it's more a surgical issue." Are there any patients that fall into like, "I think this would be more reasonable to watch and wait it out, rather than to intervene at all"?
[Nima Kokabi MD]
When there are small pseudoaneurysms, yes, a lot of times actually. I remember reading a paper, I don't know the exact number, but post renal biopsy, if you actually do a high-quality CTA or angiogram, a very large proportion of those patients have a pseudoaneurysm. We don't obviously biopsy all these patients there. We know that a lot of patients have a small perinephric hematoma that stops, and we just move on, and they don't require any further intervention.
Just seeing a tiny pseudoaneurysm that there's no significant hematoma around it, the patient is rock solid stable with the vital signs, that doesn't require an intervention right away. What you need to do at that point is to follow up with those patients very closely. Maybe do another CTA in 48 hours and if it's stable, do another CTA in two weeks. There's no real set protocol on how closely you need to monitor those patients, but the bottom line is, you need to monitor those patients, those who require further imaging. Which is still much less morbid than subjecting them to angiography. Especially, for those tiny pseudoaneurysms, a lot of times you cannot get into the sack, you may need to actually sacrifice quite a bit of kidney to embolize that pseudoaneurysm. Sometimes less is more, for sure.
[Chris Beck MD]
Especially like you said, you paint a scenario where you have a rock solid patient. It’s been my experience, especially with post-biopsy patients, that even when I go to see them in the post-procedural area, it's almost like you just know they have something going on. They're writhing in pain, the blood pressure is lower than what they were baseline and they just have a certain look of uncomfortableness to them. That's just unrelenting and not relieving your standard post-pain medications.
[Nima Kokabi MD]
That is part of the art of IR, as opposed to the science. A lot of that is really not easy to teach. It's an experience you gain through the years, and all of us have been subjected to those patients. I think the more you do, the more you realize those nuances.
Podcast Contributors
Dr. Nima Kokabi
Dr. Nima Kokabi is an interventional radiologist at Alberta Health in Chapel Hill, North Carolina.
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Cite This Podcast
BackTable, LLC (Producer). (2023, May 15). Ep. 322 – Renal Trauma Embolization [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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