Can normal saline be used to fill the balloon of a Foley catheter? The experience of a prospective randomized study in China


Chi-Fai Ng md, Division of Urology, Department of Surgery, Prince of Wales Hospital, Shatin, Hong Kong SAR, China. Email:


Background:  Despite the lack of evidence, using normal saline for inflating the balloon of a Foley urethral catheter is frequently regarded as a cause for deflation failure. We have investigated the issue by comparing the rate of deflation failure of Foley catheter balloon, using either sterile water or normal saline as the filling solution.

Methods:  Four thousand latex Foley urethral catheters (14 Fr) were randomly assigned to one of two groups: sterile water or normal saline. Each of the catheter balloons would then be inflated with 10 mL of the corresponding fluid. They were subsequently put in water baths at 37°C for 4 weeks. At the end of 4 weeks, all the balloons were deflated by people who were blind to the assignment of fluid inflated. Failure of deflation was defined as the balloon not being able to be deflated completely. The number of deflation failures was recorded and the amount of fluid aspirated from each balloon was also noted.

Results:  Of the 4000 catheters, 17 (0.43%) were found to be defective and could not be used for the study. The remaining 3983 catheters were randomly allocated into the sterile water (2011) and normal saline (1972) groups. The failure rate of deflation for the sterile water group and normal saline group were 185 (9.2%) and 157 (8.0%), respectively, which was not statistically significant (P = 0.162).

Conclusion:  There was no difference in the rate of deflation failure of latex Foley balloons by using either sterile water or normal saline as the filling solution.