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Abstract
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Background
Vial coring describes the occurrence of small rubber particles, which are formed by needles when perforating vial stoppers. These particles may be aspirated from the vial into the syringe along with the drug. Unconscious injection of rubber particles may increase the risks associated with intra-articular injections, in particular septic arthritis.
This study aimed to analyze the frequency of this phenomenon and possibilities to avoid its occurrence. We hypothesize that coring can be significantly reduced by using a thinner needle for injection than the one used to withdraw the liquid from the vial. We also hypothesized that the use of needles with a filter may avoid vial coring completely.
Methods
600 vials of 2mL, filled with sodium chloride, were divided into 3 groups (n=200 each). In group one, aspiration from the vials was performed with a standard 18-Gauge needle and the same needle was used to eject the aspirated fluid onto a 10 µm filter paper. In group two, an 18-Gauge needle was used for aspiration. The needle was then replaced for a 23-G needle through which the fluid was ejected onto the filter paper. In group three, aspiration was performed using 18-G needles with implemented 5 µm filters. Afterwards the needle was removed and the fluid ejected onto the filter paper directly out of the syringe. Subsequently, a microscopic analysis of the filter papers was performed.
Results
In none of the 600 specimen, a rubber particle was detected by naked eye. Microscopically, 20 (10%) rubber particles were detected in group one. In group two, 21 (10.5%) particles were found. In group three, no particles were visualized. The detected particles were mostly cylindrical with a mean length of 77 µm ranging from 29 µm to 214 m. The mean width was 36 µm with a range from 14 to 83 µm.
Conclusion
Our study shows the occurrence of rubber particles in the injection fluid in 10% of the cases when standard needles are used for aspiration and injection. Using a thinner needle for injection did not reduce the number of particles whereas this phenomenon could be completely avoided when a filter needle with a 5 µm filter was used. We recommend withdrawing drugs for intra-articular injections with such a needle if possible.
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