Comparison of two different cell culture methods in evaluation of biocompatibility of latex urinary catheters.

International biocompatibility standards for urinary catheters have not yet been set. The used in vivo animal tests earlier have been shown to be insensitive and expensive. The present study compared the sensitivity and other properties of two in vitro cell culture methods, the reference method of the British Standards Institution (BSI) and the thymidine incorporation method (DNA synthesis inhibition test. The cell culture toxicities of thirty-seven latex catheters were measured and 84.8% of the catheters tested passed the BSI reference test while 94.6% passed the thymidine incorporation test. The overall batch-to-batch correlation was poor (p greater than 0.05), but within brands the correlation was better. This is obviously to be explained by the differences the characteristics of the tests and/or the chemical composition of the catheters. The thymidine incorporation test is easier to perform, requires less manpower, and is therefore less liable to subjective interpretations than the BSI test. The biocompatibility toxicity limits for latex urinary catheters need to be tightened. Our experience in this study indicates that the thymidine incorporation test or tests similar to it, which can be highly automated can be recommended for biocompatibility screening in large series, and BSI reference test can be used additionally in unclear cases.