Bacterial contamination of test stimulation leads during percutaneous nerve stimulation

Objectives. To analyze the bacterial contamination of conventional percutaneous nerve stimulation (PNE) leads. Sacral neuromodulation has become an important tool for the treatment of urgency and chronic retention. Patients likely to benefit from this type of therapy are identified by PNE testing before implantation of the definitive system. Recently, a new system was introduced, using a self-blocking electrode that remains in place for both PNE testing and final implantation. PNE testing warrants an extracorporeal stimulator. Thus, using the same electrode for both external stimulation and definitive implantation may carry a significant risk of infection. Methods. Bilateral PNE testing was performed in 11 consecutive patients (8 women and 3 men, mean age 41.6 years) for either urgency (n = 7) or chronic retention (n = 4). Electrodes were placed under aseptic conditions and stimulated for 3 days. At the end of each test, the electrodes were removed and evaluated microbiologically. Results. In 5 of the 11 patients (9 of 22 leads), significant bacterial growth was detected: Staphylococcus epidermidis in 5, Escherichia coli in 3, and Enterococcus faecalis in 1. However, no patient showed signs of inflammation at the electrode insertion sites. Conclusions. Bacterial growth was found in 45.5% of the patients after conventional PNE testing under aseptic conditions. Therefore, the new electrodes may well carry an elevated risk of infection. Infection of the implant can lead to major surgical revision or even explantation. Thus, additional studies of the infection risk of this new electrode are warranted before its general use can be recommended.