Final answer:
The catheter drainage bag is kept lower than the bladder to prevent backflow of urine which if allowed, could introduce bacteria into the bladder and increase the risk of infection.
Step-by-step explanation:
The primary reason the catheter drainage bag should always be kept lower than the bladder is A) To prevent backflow of urine. By maintaining the drainage bag below the level of the bladder, gravity helps to ensure that urine flows continuously downward and does not return to the bladder, which could introduce bacteria and cause an infection. This is especially important as conditions like prostatitis in men or kidney stones in both men and women, along with the anatomical predispositions in women, can increase the risk of bladder infections. Additionally, the retention of urine can be more problematic in the elderly due to incomplete bladder emptying and weakened immune systems, further underscoring the necessity of appropriate catheter maintenance to minimize the risk of infection.