Urinary catheter structure and testing methods in relation to tissue toxicity.

Eluates from 56 latex urinary catheters from seven manufacturers were divided into three categories according to covering material (siliconized, silicone elastomer coated and teflon coated) and tested for tissue toxicity by means of cell cultures based on the inhibition of DNA synthesis. The silicone elastomer coated catheters showed the lowest toxicity. Only 4 of 13 such catheters gave unacceptable toxic values, whereas half of the siliconized catheters were abandoned as toxic. Teflon and elastomer coatings had the best protective properties against toxic substances leaching from the catheter core. The surface contour of the catheters estimated by scanning electron microscopy (SEM) did not correlate with toxicity, whereas the cracks seen on the catheters did correlate with toxicity. The simple in vivo test methods used by the manufactures turned out to be insensitive to tissue toxicity testing of urinary catheters. The method used in this study was the most reliable for assessing the safety of latex urinary catheters. Thus manufacturers using multiple and in vitro cell culture tests had products of better quality than those using only a single test or simple in vivo tests.