Safe Needling: Avoiding the Kidneys
There are a few anatomical areas that require extra consideration and training when using invasive techniques like needling. The most obvious is when needling over the lung fields. Another area that exercises peoples' consideration is in regards to the kidneys, when conceptually needling the bladder channel or lumbar paraspinals. We discuss this safety aspect in great detail in our Level 2 Advanced Spine and Lower Quadrant Course but I would like to explore some aspects in today's blog.
A 2017 article (can be accessed via Research Gate) by Chia & Haberberger examined the anatomy of the kidneys and needling in relation to the bladder meridian, which involves needling in the sagittal plane through the paraspinal muscles from posterior to anterior. In much the same way that dry needlers would when treating iliocostalis lumborum or longissimus lumborum. However, dry needlers may also be needling quadratus lumborum in this area, which is usually needled in the frontal plane, from lateral to medial and slightly posterior to the relevant transverse lumbar process. In both cases there is the possibility of needling into a kidney.
Situated within the abdominal cavity, the kidneys have some key anatomical features and are slightly different from right to left (see box Key Kidney Anatomical Considerations). The kidneys are larger than most people think and are highly mobile in association with breathing.
Safe Needling Considerations
Based on anatomy and the findings of the above and other articles, when needling in a sagittal plane, a safe depth of insertion could be considered around 25 – 40mm, which would depend on gender (males deeper), spinal level (distal segments deeper) and morphology (endo & meso deeper than ectomorph). When needling in the frontal plane for quadratus lumborum, a longer needle would usually be required, due to the greater distance travelled to reach the tip of the appropriate transverse process.
However, this is all academic consideration. What about practical reality? To add perspective to this discussion we need to consider what other 'needling' techniques are being applied to the kidney on a routine basis.
Percutaneous Renal Biopsies
This procedure started in mid 1950s, due to the unfortunate removal of 25% kidneys suspected of having a tumor when in fact they did not. The issue at hand related to lesions that were identified using imaging techniques and less that 40mm in size. Larger lesions were removed.
The procedure involved a 16 gauge (1.651mm) bored needle, that enable the taking of either a single or multicore biopsy from the kidney in patients with lesions less than 40mm. The biopsies where then examined and if found to be a tumor appropriate management was instigated.
In a 30 year review of this procedure (1387 cases), the following points were identified;
- No death
- Serious complications in 0.36%
- Asymptomatic hematuria in 24.2%
Those that developed asymptomatic hematuria were managed by lying prone 2 hrs + bed rest 22 hrs.
In another article, it was noted that hematuria should not be considered a complication, but rather a side effect of which patients are routinely advised.
In summary, it is important that at all times we apply anatomical knowledge when needling; especially in regards to awareness of avoidable neurovascular structures, joint spaces, lung fields and organs. In the case of non-intentional needling of the kidney when using a 0.25 or 0.30mm solid needle, possible damage done to a kidney in comparison to what is routinely performed during percutaneous renal biopsy, would logically be minimal and probably inconsequential. What is not discussed and may be of importance, is that if the kidney is accidentally needled, entry through the retroperitoneal cavity into the abdominal cavity may occur, with the possibility of peritonitis.
As always, thank you for reading.