Those who are sexually active know that there are LOTS of ways to “ruin the mood”. Giggling at inopportune moments (like when undressing, when you add giggling and pointing this is a real mood killer), burping, vomit, exclamations about size that are not complimentary, and of course the expression on the guy’s face when he realizes she’s wearing a waterbra. But for most of us, these are relatively rare occurrences, worthy only to bring up when you’re REALLY drunk and telling hilarious tales.
But there’s one major incident that can ruin the mood, and it can happen when you least expect it: gas.
With the advent of high fiber diets, Sci can only imagine that the gas has become a bigger problem in recent years. Whether as burps or farts, gas is…embarrassing. And for those women who have it often, it could be more than just embarrassing, it could prevent sex all together. But it could be more than just fiber. If you’re a woman who’s had a problem with “flaturia” consistently and for a long time, there could be a medical problem involved.

ResearchBlogging.org Shafik et al. “Flaturia: passage of flatus at coitus. Incidence and pathogenesis.” Arch Gynecol Obstet, 2007.
Ok ok. I admit I love this article because I get to use the word “flaturia” a lot.


So what is flaturia? Basically, it’s when your body has an uncontrollable urge to ruin the mood. You’re goin’ at it, everything is going fine, and then…oops. Apparently this can be a particular problem in women who are multiparous (have had more than one child), and so this study set out to examine what the underlying cause was.
They took 18 women, whose average number of children was 8.2 (yeah, I know, the study was done in Cairo), and compared them to women with the same number of children, who had no flaturia. The patients ONLY had a problem during sex, and not at any other time. They then took patients and controls and stuck stuff up their rectums (sounds like fun, I really hope they paid the controls…) to measure pressure and the degree of contraction of the anal sphincters.
To give you a better idea of what they found and why, I present to you: the gastrointestinal tract:

And in this larger view you can see the sphincters that divide the rectum from the anus. There are two sphincters involved, the internal and external. The internal anal sphincter is not under conscious control. The external one obviously IS under conscious control. So how does this work? Let’s do a quick overview of pooping.
1) Food waste in the large intestine accumulates, and a mass movement occurs. These mass movements occurs generally around four times a day, and often after large meals (especially after Tex-Mex). These large smooth muscle contractions of the large intestine push the fecal matter into the rectum, activating a defecation reflex. The defecation reflex relaxes the internal anal sphincter. The relaxation of the internal anal sphincter and the buildup of fecal matter in the rectum is the signal that you have to go. But luckily for most, nothing will happen until you get to a private place, in which you can voluntarily relax your external anal sphincter.
This doesn’t just occur with fecal matter, it can also occur with gas. Gas from food digestion can build up and get pushed into the rectum, where the pressure triggers a defecation reflex. Luckily, you still have control over your external anal sphincter, usually allowing you to control whether or not you’re about to fart at an inopportune moment. But we all know that the control of the external anal sphincter is…subject to the whims of fate. If you happen to, say, move a lot (like during sex), when you need to let something out…it’ll come out, presumably causing both you and your partner some embarrassment.
Of course, most people have pretty good control over when gas comes out, and though it might be uncomfortable, can hold it until a more opportune time. It’s when farting becomes involuntary that we have a problem.
So how do you measure this sort of thing? You put pressure sensors in the rectum and anus, of course. By recording the pressure normally and during contraction and distension in the patients and controls, the researchers could look at the differences. They found that normal pressure and normal squeezing were equal between patients and controls (which is good, otherwise the patients would probably have trouble controlling farting and fecal discharge more times than just during sex).
What differed was a measure known as the recto-anal inhibitory reflex (RAIR). The RAIR is a reflex that makes the internal anal sphincter relax when under pressure. In women who had problems with farting during sex, the RAIS was a lot more sensitive to pressure than in controls. There was one other major difference. Though the rectum is usually thought to be empty unless you really need to go, in some cases there is some fecal matter left. And there was fecal matter present in the rectums of ALL the patients, while it was only present in two of the controls.
The authors concluded that the more sensitive RAIR and the presence of stool in the rectum were probably the things responsible for farting during sex. But why? Well, because they’re being…buffeted.
As you’re probably aware, in women the vagina and rectum are not separated by a lot. The authors hypothesized that, during sex, the penis was whamming up against the barrier between the vagina and rectum, increasing the pressure on the rectum, which caused relaxation of the anal sphincter and the release of gas.
No one is sure why some women have this problem and others don’t. It’s possible that, during pregnancy or delivery, the muscles of the rectum become stretched and weakened, and might not recover fully in some women, causing this problem. The authors didn’t really speculate. Unfortunately, they also didn’t give these poor embarrassed women any advice on how to avoid “rectal buffeting”. It’s also possible that some methods could be found to help strengthen the muscles around that area, to help with a little more control. If I were them, I’d try to see what happens if the women in and their partners change the angle, and have the penis “buffet’ somewhere else. Though perhaps, being in Cairo, the doctors didn’t feel comfortable discussing the possible merits of a woman on top.
Shafik, A., Shafik, I., El Sibai, O., & Shafik, A. (2006). Flaturia: passage of flatus at coitus. Incidence and pathogenesis Archives of Gynecology and Obstetrics, 275 (1), 33-37 DOI: 10.1007/s00404-006-0218-z