I go into these details not because I'm into "all things urinary," but because my urologist told me that "Everyone with MS eventually goes down this road," so forewarned is forearmed.
So how is the whole thing "supposed" to work, in broad strokes? Kidneys extract what they turn into urine and pass it off to the bladder. When bladder figures out it has whatever amount in it that would be good to send along to the next adventure. bladder sends neural messages to the brain saying "Time to empty!" Brain tells bladder to let it fly (as it were), bladder sends the liquid on its way, and we're all set to start the cycle again. Besides, kinda from a spiritual perspective, urine exemplifies "stuff that I don't need any more," and sending stuff you don't need any more on its way is necessary so that you're ready simply to accept the arrival of next adventure.
For me, the challenges come out of bad wiring. Bladder does what it does but messages to brain are, from the brain's point of view, confusing or even incorrect. Brain tells bladder to do stuff but the messages don't get there and so it doesn't do what brain wants. We in the Cath Club have figured out a way to work around the "there's no way to get bladder to do what you want it to," but the messages sent to brain don't get less confusing.
Apparently, and although I haven't chatted with urologist yet about this, my Basic Doctor tells me that my bladder is spastic (just like so many of my other muscles) which means that it doesn't really expand fully and freely; the other day, I did a nice voluminous cath, lay down, felt Alan screaming at me, cathed again, and again got a nice voluminous cath. Now, if the New Year's Eve champagne bottles worked that way--I'm empty! No I'm not...I'm still full! Have more!--Moët and Chandon would have a very different way of looking at the holiday.
Even as I type this, Alan is whining, ever and ever more insistently. The whole "catheterization" process goes way way WAY more easily when it's cooperative... when Alan welcomes the cath. My GP guy says that the whole plumbing system needs to relax, so that the "screaming" is only sensory not muscular, hence the "cooperative" thing.
And so to come full circle, while I was typing the above paragraph, Alan was most distinctly calling for attention, so I took an "aside" moment to visit the "necessarium" and do the Cath thing, and Alan cooperated and responded happily. Enough lube is important, if you're using coude´ catheters, angle matters too... but nothing trumps cooperation. Happy to play the game urethra, happy to play the game bladder, things go beautifully. And to find the funny in it all, after the initial "emptying," I poke around a bit with the catheter to find the fluid level, and I do, but that level keeps changing. Interior of the bladder isn't like a real balloon, its inner wall has bumpy bits (hold up your hand, flat, palm facing you, and looking at your fingers you get the idea of the "bumpy" of the inner bladder wall, which becomes more "interesting" to work with when the basic musculature is spazzy and thus creates places for fluid to collect and avoid the outlet provided by the catheter. The more things change, the more things change.
And a final note: My doc, who's both in the MS and the Cath Club, says that if you're using catheters like we do, you're going to get infected ("UTI" means "urinary tract infection"), so don't be surprised when it happens. But he also recommends, and because of what this is I can freely share it with you, barley tea. Or, as the Japanese call it, mugi (moo-gee (hard G)) cha.
Has nothing to do with camellia sinensis, the plant from which what we call "tea" comes, and therefore has no caffeine, and for folks like us this is a big plus, it is not at all diuretic. But my doc says it just cleans out the system, which is after all what the whole "elimination" system is all about. If you brew it from scratch yourself from only barley seeds, or if you use a tea bag (very easily found in Japanese markets), the flavor will be different... but it's not bad at all either way (I prefer the "from seeds" version), just be your own tea master and brew it as long as you think you should; the worst you toss it and try again, what with the cost of barley, isn't a big deal. Considering whatever else you may have to struggle with, this ain't bad, brewing barley.
And as they said on Babylon 5 in the episode "Learning Curve"... So ends the lesson.