Dialysis Fistulas

Dialysis fistulas are also prone to infection, particularly if they include implanted prosthetic material, while native vessel arteriovenous fistulas are relatively resistant to infection. Staphylococcus aureus accounts for 60-90% of access site infections, suggesting direct contamination from skin at the time of access. As with other graft infections, clinical findings can be extremely subtle and are completely absent in approximately one-third of cases.

When an infectious process is limited to a small area away from the suture line antimicrobial therapy and debridement may be sufficient to eradicate the infection. Unfortunately, in many cases this is insufficient and the arteriovenous fistula must be completely removed.

Nuclear imaging of a dialysis fistula can be difficult to perform and challenging to interpret. Frontal and profile views of the fistula are required, but it can be difficult to control for the degree of forearm pronation. Furthermore, some camera designs are cumbersome to position for areas close to the antecubital fossa. The large amount of blood contained within the fistula can often be seen as low-grade activity, especially on early images or when significant erythrocyte cross-labeling has occurred. Occasionally, normal bone marrow can be a source of confusion and highlights the importance of mapping any uptake to the fistula itself. Clinical assessment of the patient while still under the gamma camera is an essential step. With these precautions nuclear imaging can be highly accurate in the diagnosis of an infected fistula (Fig. 16).

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