Part 3 of a 5-part series on the advantages of a freehand technique over a needle-guide system for ultrasound-guided biopsies. If you haven't read the rest of this post, please start at part 1.
In part 1 and part 2 of this series, I discussed issues related to planning, scanning, prepping and local anesthesia. In this part, I will first describe more about locating your ideal sites (not a single site). As I mentioned, I always mark the spot of insertion and find at least one point for viewing. This planning stage is usually the longest part of the procedure, other than the consent and timeout. The longer you plan, the faster the actual procedure goes.
Preferred subcostal approach
Generally, for liver lesion biopsies and some abdominal mass biopsies, if the lesion is high in the abdomen, I prefer inserting the needle subcostally, rather then intercostally, although I don’t adhere to that rigidly if it simply isn’t possible. Since you are penetrating the diaphragm/potential pleural space for an intercostal approach, you may be concerned about seeding the pleura with tumor or infection. In these cases, you want to at least attempt to plan a subcostal approach.
So, particularly with superficial lesions high in the liver, the best subcostal approach may require a very steep angle, sometimes with the needle almost parallel to the surface of the abdomen. It is often impossible to use a guide to achieve this because the footprint of the transducer plus the guide is too long, the guide does not allow such an angle and the lesion may not be visible for the position you have selected for insertion. Additionally, with a steep angle, often a fair amount of pressure is necessary and the sharp edges of the guide may be uncomfortable as they dig into the patient. Your position may also be awkward. Any of this sounding familiar to you guide-users?
More needle length available
One other issue that guide-users may not appreciate is that because of the required step-off of the needle portal to the skin, you cannot insert the needle hub all the way to the skin as you can freehand. This may require you to select a longer needle, which is more awkward to use.
Watch from anywhere
Freehand, you can position the needle optimally and then place the transducer intercostally, subxiphoid or elsewhere - wherever you can see the lesion and needle. You are no longer limited when picking your insertion point to accommodate for the fixed geometry of the guide. You can actually do biopsies that you might otherwise abandon because you can’t figure out how to do them with the needle guide. I have been invited in to help salvage these types of difficult procedures and simply have removed the guide. I have been able to acquire the tissue within a few minutes while the first radiologist had struggled for over 1/2 hour trying to use the guide with a difficult angle
See the lesion and needle better
Also, if when you start the procedure, and you are using the guide, you may find that you cannot see the lesion as well as you did when you marked the spot. There is a reason for this. If you use the guide, you likely will have a plastic sheath and gel inside the sheath. There may be a few gas bubbles trapped in the gel. The presence of the sheath and the gel actually degrades your visualization of the lesion and needle. Without the guide, sheath and gel, your visualization should be comparable to when you localized the lesion when you started.
In part 4 of this series, I will discuss the final stages of planning and actually performing the biopsy.
In this series:
- part 1 - introduction
- part 2 - planning and preparation
- part 3 - approach and visualisation
- part 4 - the biopsy
- part 5 - additional benefits & conclusion
- survey results
Lincoln L. Berland, MD is Professor Emeritus of the Abdominal Imaging Section of University of Alabama at Birmingham.
NB: Opinions expressed are those of the author alone, and are not those of his employer nor of Radiopaedia.org.