April 23, 2019
Infection remains a devastating complication of penile prostheses
Penile prostheses are considered the gold standard treatment for medically refractory erectile dysfunction, and overall these devices have high success and satisfaction rates with low rates of mechanical failure. However, infection necessitates device removal and can be devastating to patients.
Despite multiple innovations in prosthetic surgery, including anti-infective device coatings, surgical techniques to limit exposing the wound to skin flora and washout protocols with copious intraoperative irrigation, infection remains a serious concern for the prosthetic urologist.
Landon W. Trost, M.D., a urologist at Mayo Clinic in Rochester, Minnesota, who is also trained in andrology, made one specific change in his prosthesis operative practice: He switched from using undiluted povidone-iodine for intraoperative irrigation to using vancomycin-gentamicin. After this change, Dr. Trost noticed a dramatic reduction in postoperative prosthesis infections.
Povidone-iodine associated with 9 times more postoperative infections
Dr. Trost and a team that included Tobias S. Kohler, M.D., M.P.H., an andrologist and expert in prosthetic surgery at Mayo Clinic in Rochester, Minnesota, set out to rigorously examine this anecdotal decrease in infection rate. Over a four-year period, they closely followed all patients after penile prosthesis surgery, with thorough investigation of medical records and periodic surveys to identify any complications managed elsewhere.
The rate of infection was compared among patients who had povidone-iodine irrigation used intraoperatively versus those who had vancomycin-gentamycin. The team found that patients in the povidone-iodine group had significantly more infections. To ensure that this finding was not due to other associated clinical factors, the comparison was repeated while controlling for multiple patient characteristics, including:
- Body mass index
- Other medical conditions
- Smoking status
- Additional surgical techniques including prior penile surgery
Even after controlling for these potential confounders, povidone-iodine irrigation continued to be associated with a ninefold increase in the likelihood of developing an infection.
Investigating irrigation solutions to improve patient outcomes
Given this impressive finding, the research team looked to prior research. There is strong evidence that povidone-iodine, especially in stronger concentrations, is toxic to tissue. It is likely that this toxicity leads to tissue damage, which then makes infection more likely. In addition, the choice of povidone-iodine as an irrigant is quite arbitrary.
Urologist John J. Mulcahy, M.D., Ph.D., who popularized the povidone-iodine washout protocol in research published in Journal of Urology, initially chose to use povidone-iodine at the recommendation of a trainee on his service who had recently seen it used on his orthopedics rotation.
Orthopedic colleagues at Mayo Clinic's campus in Rochester, Minnesota, were also interested in the findings and shared literature from their specialty showing that chlorhexidine may be a safe alternative to povidone-iodine as well as being effective in breaking down biofilm, a driving factor in prosthetic infection.
Overall, the findings have reinforced the decision to no longer use concentrated povidone-iodine as an intraoperative irrigation solution during penile prosthesis surgery. Further research is needed to determine the best alternative irrigation solution.
For more information
Brant MD et al. The prosthesis salvage operation: Immediate replacement of the infected penile prosthesis. Journal of Urology. 1996;155:155.