Biomedical Engineering Reference
In-Depth Information
Fig. 1.
The processes following stent insertion that lead to bacterial adhesion, infection, and
encrustation. Following stent insertion, urinary components deposit on the surface, forming
anchor points for both bacteria as well as ions/minerals. Subsequent bacterial colonization
and proliferation leads to the formation of a resistant biofilm that leads to subsequent
infection. In addition the interaction of ions/minerals with conditioning film components
and bacterial induced crystallization will facilitate encrustation of the device. Inhibition of
the common step of conditioning film deposition is a potential step in preventing patient
symptoms associated with indwelling ureteral stents.
2. Problems arising from stents
Stents have been associated with increased morbidity causing infection,(Riedl, Plas et al.
1999) encrustation,(Paick, Park et al. 2003) hematuria,(Damiano, Oliva et al. 2002; Joshi,
Newns et al. 2003; Joshi, Chitale et al. 2005) and discomfort (Joshi, Stainthorpe et al. 2001;
Joshi, Okeke et al. 2002). The Ureteral Stent Symptom Questionnaire (USSQ) looks at
different facets of life including sexual function which has been shown to be negatively
affected by the presence of a stent (Sighinolfi, Micali et al. 2007). In fact, ureteroscopes,
intracorporeal lithotriptors, and ureteroscopic techniques have improved to the point that
the major morbidity of ureteroscopy has become the stent left
in situ
postoperatively
.
Studies evaluating differences in postoperative complications and stone-free rates in stented
compared to non-stented patients have shown that stents are not a routine requirement
following uncomplicated ureteroscopy (Hosking, McColm et al. 1999; Borboroglu, Amling et
al. 2001; Denstedt, Wollin et al. 2001). The uncommon, but most severe problem arising from
stents is the “forgotten stent” that is left in place for several months to years. These stents
become encrusted and create difficulty for both patient and urologist, especially since their
