Factors influencing the time long-term indwelling Foley catheters can be kept in situ.

To study the factors that influence the frequency of unscheduled catheter changes, patients with long-term indwelling Foley catheters were followed up for 48 weeks. A marked interindividual difference in the need for unscheduled changes was noted. The amount and composition of the encrustations precipitated on the catheters and urine osmolality influenced the frequency of unscheduled catheter changes. There was no correlation between the time a catheter had been in situ and the amount of encrustations on catheters changed on schedule after various times in situ. This indicates that time does not govern the amount of encrustations accumulated.