normal anatomy vs. prolapse

Body: 

Hey ladies,
I don't really know where to post this question, so I'll just post it here! In normal anatomy(whatever that means) are there any changes in the vagina when the bladder or rectum are full? The reason I ask is that I have a lump in my abdomen that shows up with gas. It isn't a hernia. Apparently, because I am very thin, it is easy to see activity in my digestion. So, if you can see gas in your belly, it seems logical that when there is gas in your rectum it may cause a little distention on the back wall of vagina. Is that possible?

Hi Lyricmama

Oh yes, I think gas can do a lot of things. For a start it takes up space, which is why we feel bloated when we are producing a lot of gas. Gas really shoves things around if we are constipated at the same time.

If you remember your high school physics lessons, at a constant temperature pressure and volume are inversely related, ie when gas is under pressure it expands to occupy a greater volume, so that the pressure inside the bowel becomes equal to the pressure outside the bowel. In turn the pressure outside the bowel equalises itself to air pressure outside the body. When we fart forcefully it is a sign that the inside of the bowel is under pressure it cannot dissipate by increasing in volume, so the whole bowel will be pressing on something where the pressure is greater. Constipation may mean that the gas bubble cannot get past hardened stool, so the pressure becomes localised, and I figure that means it could press quite hard and blow out a rectocele if we cannot pass the gas, because the fascia surrounding bowel cannot contain its volume. It is our old friend intraabdominal pressure exerting itself in the wrong direction again.

Louise

so, in a normal vagina, would there be movement on the back wall if there is a lot of gas trapped in the rectum? How immobile is the rectovaginal fascia?

In the normal vagina you can sometimes feel stools as they move dow, just not as much as with a rectocele, so I'd imagine you could feel a good lot of gas.

any one correct me if i'm wrong, but it's not that thick a wall, so makes sense (remember reading this in a thing on vaginal self exams as well, of what you might feel...)