A stab in the dark

Abstract

Procedural guidance with ultrasound is challenging traditional medicine. And for good reason – precision is an ally whenever you are inserting a needle into a human body. With some imagination, I am able to conjure up a gruesome Hollywood-esque image of someone gripping a syringe in a gloved fist and thrusting it towards a body with the intention of hitting a target under the skin. In my mind, there is an element of chance as to whether the needle hits the intended anatomical target. It's a stab in the dark. In a more nuanced and stable clinical scenario, the insertion point is carefully considered and the odds of missing may be relatively low. But no matter how low, it seems intuitively sensible to use any imaging guidance available. And increasingly, that guidance is provided by ultrasound. Ultrasound has been established as a helpful addition to inserting intravenous lines, taking biopsies and draining free fluid, to name but a few.

If one assumes that the person inserting a needle has absolutely no knowledge of underlying anatomy and is simply taking a stab whilst hoping it will hit its spot then it is easy to perceive the massive benefit of ultrasound-guided procedures. But that simply isn't true. Medical students spend many hours learning about surface anatomy and how it relates to the underlying layers of tissue, muscle and bone below the skin. Doctors have a great understanding of anatomy and use their hands to palpate for certain underlying structures such as bony processes, tendons and veins, in order to piece together an image in their mind about the underlying anatomy. Anyone who has had blood taken knows that those technicians who do this are adept at feeling the anatomy on the inside of the elbow to find a vein to puncture and drain blood from no matter how deep it is. It is a well-honed skill.

But taking blood is one thing, injecting substances is quite another. Intra-articular injections for the treatment of joint osteoarthritis have been popular for some time and are safely performed using anatomical landmarks only. But increasingly, practitioners are using ultrasound to guide needle placement. In this issue of AJUM, Oo et al.¹ have performed a systematic review of ultrasound-guided injections and concluded that clinical outcomes are superior compared with landmark-guided injections. As a potential patient, I can see how this may build confidence in the procedure, but the added benefit of improved clinical outcomes makes ultrasound guidance even more compelling.

All new approaches come with a learning curve however and potentially some questions about who should do these procedures. Those with extensive landmark-guided experience may find the ultrasound hinders the process at first. And conversely, those with ultrasound experience may not have the confidence with landmark-guided procedures. Having two professionals (one an ultrasound expert) working side by side may seem attractive but it would be cost-prohibitive as the number of ultrasound-guided procedures increases. Furthermore, I have heard concerns from some practitioners that less experienced practitioners will become too reliant on ultrasound for their procedures; and that they will lose the art of the traditional landmark-guided techniques but if ultrasound is better for patients is this a problem?

Just as injecting substances into joints requires precision, so too does the removal of cells from the body. Because needle aspiration requires precise anatomical alignment, in order to ensure the correct cells are sampled, ultrasound is potentially very useful for refining this technique. In this issue of AJUM, Akahoshi et al.² present a small study where they evaluated the efficacy of ultrasound-guided fine needle biopsy of hypoechoic lesions during endoscopic examinations.

And to aid the training of practitioners in ultrasound-guided needle insertion, McKinley et al.³ provide a description of a do-it-yourself ultrasound phantom for needle guidance. It provides novices a way to practice their needle insertion and through a series of wires and LED lights gives direct and real-time feedback (in the much the same way as the ubiquitous game of ‘Operation’ but without the loud buzzer!).

I'm firmly of the opinion that ultrasound guidance is becoming standard care and the added expense (if there is any) will result in better outcomes for patients, as well as increasing the confidence of practitioners (and patients) with their procedures.