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An Electron-Microscopic Search for the Perfect Acupuncture Needle

by Electron Microscopy Department, London School of Tropical Medicine and Hygiene

Method
Unselected, disposable acupuncture needles were acquired from various sources: either bought by the authors or kindly donated by members of the British Medical Acupuncture Society (BMAS) or needle suppliers exhibiting at the BMAS Autumn Scientific Meeting held at Imperial College, London in October 1999. The collection comprised samples of most of the popular ranges of disposable needles used in the UK and Germany, many currently available internationally. Some were manufactured in China or Taiwan, some in Japan.

Three of each type of needle were removed at random from their wrappings. Each needle tip was then mounted separately on a block and placed in the electron microscope chamber. Particular care was observed to avoid handling the needle tip or contaminating the chamber with dust particles. Photomicrographs of each needle were taken at low (x 39.37) and high (x 612.5) magnification, except in the initial trials with the test needle (S.1) where magnifications are shown on the plates. All photographs taken are shown here except those that were duplicated or of poor visual quality.

Findings
To our surprise, no needle was perfect and most showed significant faults, some apparently serious. There was no correlation between the retail cost and the quality of needle tip, and several types of needle showed a wide range of quality within the three randomly chosen sample needles. Faults noted were:

Metallic surface deposit (scuff)
Scratch marks along or across the needle
Needle tip bent, hooked, stubbed or malformed
Lumps and irregularities in the needle surface
Silicone coating of the shaft and tip (S.6)

The full collection of photographs is shown here.

Clinical
There have been many reports of needles accidentally broken in the skin or muscle of a patient. These are no doubt due mainly to microscopic faults allowing a fracture to occur after manual or electrical manipulation or muscular contraction. Apart from these, the only recorded problem from a faulty needle has been a report from the United States of the silicone coating of a needle becoming separated and remaining in the skin after withdrawal of the needle.

The clinical author (SH) has occasionally noticed a fine grey dust-ring on the skin surface around needles in situ or more commonly a dark discolouration of the exit hole after needle withdrawal. We presume this is scuff that has been wiped off the needle surface during insertion. It is interesting that this has never been reported previously.

Discussion
Our first reaction, as no doubt yours will be, was one of "Shock, Horror". But, on reflection, many millions of these "faulty needles" have been used clinically without report of ill effect, so there clearly is no significant danger from using them. Indeed, the needling sensation (de qi) is thought to be caused by muscle fibres being caught and twisted on the needle tip, which would occur more surely if the needle tip were irregular. So a perfectly smooth needle might actually not be as effective clinically.

Acknowledgements
This work was supported by a grant towards the electron-microscopy from the BMAS. The authors would also like to thank Dudley Tovey for initiating the project, Dr Felix Mann for advice in selection of needles, and needle suppliers at trade stands at the 1999 BMAS Autumn Scientific Meeting for kind donation of samples.

Note
As the samples tested were too small to make meaningful comparisons, and no needle type was conspicuously free from defect, we felt it unfair to name the manufacturers of individual needles. However, suppliers may obtain details of their own needles from the first author.

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