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.
This can happen, even if you do not have medications. A catheter may also be used if you must stay in bed for any reason and a bedpan isn't working or appropriate for you. (Some mothers prefer a catheter to a bedpan.) It may also be used if the doctors need to collect your urine for testing for any reason.