What Is A Normal Bladder

Since we're talking so much about bladder dysfunction, I just want to take a minute here to understand what is a normal bladder. So the normal bladder is a bladder that allows for an appropriate age-appropriate capacity, and uh we can actually calculate what a child's bladder capacity should be using a formula where we take the child's age and years plus 2. So for a 5 year old child, 5 + 2 is 7 multiplied by 3, 210 mL, and that's an expected bladder capacity for a 5-year-old child. We want the bladder to be appropriately stretchy, elastic, and that's called compliance. And so it should be able to stretch and hold urine, that 210 mL of urine in a 5 year old child at a very low pressure. It should also have a functional ureterovescul junction, so where the ureters enter into the bladder, that junction should be functioning so that there's no reflux backward flow of urine to the kidneys. Should have an intact bladder, neck, and sphincter so that when the bladder is filling, the sphincter is tight, not letting any urine leak out. When it's time to empty, that sphincter should relax completely and allow the bladder to empty to completion. And then the ureters have to be healthy, healthy so that they can propel the urine from the kidneys down to the bladder. And we can graph out the function of the bladder and look at, you know, when is the bladder staying in that healthy range. So we use a physics principle called Starling's law that helps us understand how functional and elastic is the bladder and when is the bladder going out of its safe range.