Power is the probability that a study will reject the null hypothesis. difference between the null and alternative hypotheses. level of significance, and the null vs. alternative difference. a numeric example of power and sample size estimation for the one-sample case.
During the procedure the patient is unconscious and unaware of the need to urinate. After the procedure, however, it may not be safe for the patient to walk. They may be too sick to take care of their own bathroom needs or their surgeon may feel that a catheter is best for their particular recovery.
When inserting the catheter, a lubricant should be used (sometimes the catheter is lubricated already). This makes it easier to put the catheter in place and helps avoid infection. If you are using a sachet of lubricant, this should be used once and then thrown away.