I'm really curious about this as well. From what I've read, the "average" capacity when you will get a strong urge is 500-650ml. "Large" is apparently greater than 650ml.

With me, it seems as if sometimes my bladder can hold about 6-8oz before I get a strong urge to go. But other times, it can hold twice that before I'm uncomfortable. Twenty ounces is impossible though. I could never hold that much. I've never had full urodynamics performed. This issue has been affecting me more frequently, as of late, so I may be closer than I think to getting a whole bunch of tests done. What irritates me about this is the seemingly wide variety of capacities that my bladder has before it sends the signal that I have to go. It's frustrating to go to the bathroom to go just a small amount, then go back in another half an hour.

Yeah, I've noticed the same thing, as regards to being able to hold different amounts at different times. For me 12 ounces is about the maximum limit I can hold (have found that out in a variety of conditions) but I sometimes get the strong urge at 6-8 oz as well.

I think it has to do with what is in your system (things like sugar and caffeine make me have to go a lot worse than normal with a lesser amount), and also with psychologically how you feel about what's going on. Being nervous or tense will make me have to go more, as will being focused on having to go or worried about being able to make it to the next available break (one of those vicious circle things, I guess). The times when I can hold the most are when I'm distracted by something (like being engaged in a task or focused on something else) and so by the time I need to go my bladder is REALLY stretched out, and at those times I am definitely "holding" more than I could ever manage under normal circumstances when I was thinking about how badly I have to go.

I'm wondering if that's part of the deal at night -- if at night because you're not doing anything else you're not able to consciously control those muscles to hold it back and so your bladder gets "full" before it's at maximum capacity? It's a good question anyway... thanks for your insight!

I was hospitalised for viral encephalitis about 20 years ago and I was in and out of consciousness. My blood pressure soared and I had overflow incontinence. I was catheterised and there was 1.6 litres of urine in the bag as i was transferred to an neurological hospital in an ambulance. The nurse was impressed by the volume!! Something had gone strangely wrong and I had gone into urinaty retention. The next day I then reverted to normal for me.

Michael,

Thanks for sharing -- it is amazing the different things that can happen to the body with different illnesses and the urinary tract is no different. Obviously I'm guessing 1.6 liters is way more than you would normally "hold" at a time!

What was "normal" for you before and after your illness? Have you been diagnosed with a "small bladder" under other circumstances or do you think your bedwetting is a result of other things? I know there are a lot of different reasons why people wet the bed, and also that a "small bladder" doesn't always mean the physical size of the bladder so much as what it can "functionally" hold at a given time before losing control.

Another question -- did you notice any long-term changes in your wetting or bladder function from before to after your illness? I had a bad case of mononucleosis when I was in college which severely exacerbated my wetting for a LONG time -- and I'm not sure if my bladder was affected, or my nerves, or what, but it took me a long time (several years in fact!) to recover from that and reduce my wetting to what it had been before I had mono.

Thanks again for sharing!

adam77,
Last November my urologist checked my bladder capacity, and told me that it is four ounces. Ten years ago I had a urinary sphinctertotmy, in which my urinary sphincters were surgically destroyed. So, I leak continually, and will continue to do so for the rest of my life. At its worst, prior to the surgery, my bladder capacity was 1.25 ozs., so four ozs. is an improvement, of sorts.

I recently had a ultrasound and found that my bladders capacity was 400 ml and not a drop more. I had to have an extremely full bladder for the test and it was extremely uncomfortable. In fact when they pushed down I started leaking. The test was to show how much was left in my bladder afterwards

Interesting. Sounds like a lot of us are in pretty close to the same ballpark here -- which is significantly lower than "normal", although the estimates for what a "normal" adult bladder can hold seem to be all over the map (probably depending on whether they're talking about first feeling the need to go, or having an intense need to go or actually physically starting to uncontrollably wet yourself).

I actually just came across an interesting paragraph when I was looking through an old children's medical guide I found in our basement the other day. It had about a 4-5 page section on bedwetting, and in one place it stated that an older child needs to develop a bladder capacity of around 10-12 ounces (which would be about 300 - 375 ml) in order to stay dry at night. It was an older book, written in the 70s maybe, but I wonder if there is something to that. As an adult, 10 to 12 ounces seems to be right around exactly where my capacity is -- and I'm kind of perpetually hovering somewhere between dry and wet at night.

Of course I'm sure there are other factors, like how well your body is able to wake up in response to a full bladder, that are probably at work too. But then, I also wonder, wouldn't it be easier for a larger bladder to be able to wait for the body's natural process of waking up to take over? Assuming it takes a certain amount of time for the bladder signal to travel to the brain and for the brain to complete the process of arousing from whatever stage of sleep you're in -- and the bladder is still filling and stretching during this whole time -- maybe a 16 ounce bladder has enough "stretch" to it to be able to wait comfortably for the brain to wake itself up, while a 10 ounce bladder is more likely to reach its limit and spill before that happens?

Anyway, I've always been really curious about how this stuff works -- maybe it's interesting to some others here too. :)