# Why don't we pass air when we pee? **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2005, 3:17pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248 "2005-05-17T15:17:30Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [May 18, 2005, 11:50am UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/21 "2005-05-18T11:50:50Z")
> [@Nunavut Boy](#): > > **KarlGauss** I, for one, am interested in these urinary fistulae. Please continue. Any sort of horrible personal anecdotes would be appreciated. I second this request. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [May 18, 2005, 1:15pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/22 "2005-05-18T13:15:28Z")
Although the urinary system is normally distinct and separate from the intestines, connections between the two can be formed. In diseases such as Crohn’s Disease (an inflammatory condition of the entire digestive tract), diverticulitis (inflammation of the large intestine at the site of abnormal, but common, outpouchings), and with cancer or trauma in or around the bowel, a connection can develop between the urinary tract and the intestine. The most common of these abnormal connections (i.e. _fistulae_) is between the bladder and the large intestine. Symptoms include pneumaturia (farting through the pee tube), feculant urine (!), and recurrent urinary infections. Surprisingly, perhaps, such fistulae are NOT an emergency and are often chronic. This is primarily a surgical condition, and is thus not something I have much professional experience with. But, how’s the above for a start? ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [May 18, 2005, 2:49pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/23 "2005-05-18T14:49:56Z")
Terrific! ---
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [May 18, 2005, 2:55pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/24 "2005-05-18T14:55:07Z")
For some reason I burst out laughing when I read “feculant urine”, I think I have a new insult. “Get outta my face you streak of feculant urine!!” ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [May 18, 2005, 3:29pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/25 "2005-05-18T15:29:38Z")
> [@](#): > > Bacterial decomposition produces methane. Hence nasty smelling gaseous products… nitpick – methane is odorless. It’s the aromatic byproducts of other processes that produce the distinctive odor. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [May 18, 2005, 5:54pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/26 "2005-05-18T17:54:57Z")
I don’t think it’s too difficult to pick out the problem demonstrated in [this X-ray](http://www.surgical-tutor.org.uk/pictures/images/lower_gi/pneumaturia.jpg). Before looking at it, note that air, or gas, looks dark, almost black, on an x-ray, whereas water (fluid) is more greyish. Bones are the brightest. On the x-ray, you can see a large amount of air forming almost a dome over the urine in the bladder. You can also see small patches of _normal_ “air”, i.e. bowel gas, arched over the top of the bladder (they are the dark spots located here and there in a horseshoe shape). That is from gas in the large intestine. The relatively large dark area towards the upper right is due to air in the stomach. ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [May 18, 2005, 6:10pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/27 "2005-05-18T18:10:23Z")
My gosh, **Karl** , that amazing. Appropriately, it looks like a giant mushroom cloud. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [May 18, 2005, 6:19pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/28 "2005-05-18T18:19:37Z")
> [@Little Bird](#): > > There is no way for air to get in there. The urine is extracted from your blood, and if you have air in your blood you will have more things to worry about than farting when you pee! I know what you are getting at but this sounds odd. We had better have air in our blood. ---
**Author:** ![Hombre](https://avatars.discourse-cdn.com/v4/letter/h/ecb155/32.png) [@Hombre](https://boards.straightdope.com/u/Hombre)\ **Post date:** [May 19, 2005, 7:29am UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/29 "2005-05-19T07:29:24Z")
[spit take] pee fart [/spit take] [http://www.strindbergandhelium.com/absinthe.html](http://www.strindbergandhelium.com/absinthe.html) ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [May 19, 2005, 7:58am UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/30 "2005-05-19T07:58:07Z")
> [@KarlGauss](#): > > [this X-ray](http://www.surgical-tutor.org.uk/pictures/images/lower_gi/pneumaturia.jpg). Woohoo! Titties! ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [May 19, 2005, 11:35am UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/31 "2005-05-19T11:35:19Z")
> [@spingears](#): > > Physiology 101. > Carbon dioxide is the product of oxidation or combustion. Also by photosynthesis. > Bacterial decomposition produces methane. Hence nasty smelling gaseous products… Physiology 102. Carbon dioxide is the product of combustion or aerobic respiration. It is an _input_ to photosynthesis, not a product thereof; carbon dioxide plus water equals sugar plus oxygen. Methane is one possible product of anaerobic respiration, though I am not biologist or chemist enough to reiterate the reaction that is going on or explain where the energy is being released. It’s similar though not identical to fermentation, which turns sugar into alcohol and carbon dioxide in the absence of oxygen, or the process in your muscles that turns glucose into lactic acid when you’re exercising too fast for your oxygen intake to keep up. (You then have to slow down and metabolise the lactic acid to carbon dioxide and water.) ---
**Author:** ![St.Urho](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@St.Urho](https://boards.straightdope.com/u/St.Urho)\ **Post date:** [May 19, 2005, 10:48pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/32 "2005-05-19T22:48:28Z")
> [@David Simmons](#): > > I know what you are getting at but this sounds odd. We had better have air in our blood. I believe that **Little Bird** was referring to an [air embolus](http://www.rashaduniversity.com/mrashad/venairem.html), which is a potentially deadly condition. You don’t actually have air in your blood- oxygen and carbon dioxide diffuse across membranes in the alveoli and the oxygen binds to hemoglobin and is transported from there. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [May 19, 2005, 10:56pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/33 "2005-05-19T22:56:45Z")
> [@St. Urho](#): > > I believe that **Little Bird** was referring to an [air embolus](http://www.rashaduniversity.com/mrashad/venairem.html), which is a potentially deadly condition. > > You don’t actually have air in your blood- oxygen and carbon dioxide diffuse across membranes in the alveoli and the oxygen binds to hemoglobin and is transported from there. Yeah, I knew what she was getting at - air bubbles - but it struck me sort of funny. But I disagree about no air. I’m pretty sure oxygen and nitrogen are both dissolved in the arterial blood and nitrogen in venous blood. It’s the nitrogen coming out of solution when the pressure is lowered that causes bends. I suppose it is possible that at normal atmospheric pressures not much nitrogen diffuses into the blood but it sure does so at the pressures divers encounter. ---
**Author:** ![Quasimodem](https://avatars.discourse-cdn.com/v4/letter/q/e274bd/32.png) [@Quasimodem](https://boards.straightdope.com/u/Quasimodem)\ **Post date:** [May 19, 2005, 11:23pm UTC](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248/34 "2005-05-19T23:23:46Z")
And I have been wondering (and as a respiratory therapist have written for a grant) if we have vocal chords in our rectum? I know the obvious answer is Boyle’s law of changes in volume and pressure (or is it Gay-Lussac’s? 🙂 ) But so many of us have developed the talent for talking “out of our asses” lately, that I just have to wonder. 😉 Please excuse this innocent little bit of a joke. I don’t usually do that and I mean no disrespect to the OP. Thanks Q [Previous page](https://boards.straightdope.com/t/why-dont-we-pass-air-when-we-pee/304248.md?page=1)