Assessment of bio-safety of low-cost polyurethane urologic stents used in developing countries

Abstract

Background: Ureteral stents, despite their ubiquitous use, have not been evaluated for their safety and strength after removal from the patient. While literature is available from the industry with regards to manufacturing and specifications of stents, what happens to a stent after it is inserted into the body, still needs to be explored.

Materials and methods: We conducted a methodical study of 153 consecutive patients with urological problems who were stented with inexpensive polyurethane stents. Once removed from the patients, the stents were analyzed for breakload, tensile strength, elongation, pH, decomposition temperature, residue as well as diameter change.

Results: There was no significant change in the physical and mechanical properties of the stent after clinical use and the variance was within the acceptable range of biomaterials. There was minimal leaching of material and color change in all stents.

Conclusion: The cheap polyurethane stents were found to be safe for use in patients, for the short time periods of in situ stenting. The degradation of physical and chemical properties of the stent was not significant. Thus it can be safely said that the stents currently in widespread use are cost-effective and physically safe for short spans of time.

Keywords: Cost-effective stents; polyurethane DJ stents; ureteral stents.

Figure 1

(a) Results of breakload versus stent density. (b) Results of tensile strength versus stent density

Figure 2

(a) Correlations among breakload, tensile strength, elongation. (b) Correlations among breakload, in situ days, tensile strength

Figure 3

(a) Density as a function of elongation. (b) Density as a function of pH

Figure 4

(a) Density of the used stents with regard to their decomposition temperature. (b) Density of the used stents with regard to their residue. (c) Density of the stents with regard to UV–visible spectro-photometric data