One study found that nurses who often held it in all day due to job constraints had nearly double the normal bladder capacity and turns out they were totally fine but that doesn’t mean that you should hold it in if you can help it ’cause your bladder might not be the only thing to stretch. You may also stretch your external sphincter muscles. Those are important muscles connected to the outside of your bladder that are the gatekeepers of your golden liquid.
Relax them and you release the flow, but if you overstretch them, you can actually lose control. This is rare and it usually takes decades of holding it in too long to reach that point but once you do, it can lead to some awkward and even dangerous situations.
For example, with less overall control, you risk leaking urine when your bladder is full and not emptying it all the way when you finally do go. Not only can this increase your need to urinate more often since your bladder fills up quicker, it can also lead to a serious disorder called urinary retention where you end up with too much urine in your bladder for too long and since your bladder is basically a warm, wet bag of body waste, it’s the perfect breeding ground for harmful bacteria that will cause all sorts of damage.
Even worse, if you’re really unlucky and retain too much urine, it may back up into your kidneys. This can cause kidney failure and ultimately death. The good news is you’re more likely to just lose control of your muscles and pee way before your bladder hits this point.
Why not reduce the risk altogether and just go to the bathroom? Remember, your health is more important than what is preventing your from peeing.