Heather Corinna replies:

Delilah: what you're describing is most likely a completely normal physiological response to being sexually aroused.

Part of female sexual arousal, much like erection for men, is swelling of the genital tissues due to blood pooling in the pelvis: the clitoris (both externally as well as internally), the outer and inner labia, even the mons will often get larger and "puffy" when a woman is very sexually excited. How much or how often that happens really depends on a given woman. Some women get that aroused and have that response all the time, others less frequently, and some have yet to ever have it happen. You may not be noticing or feeling it as much when it's going on, because you are (understandably) distracted while sex is going on.

But it's not really something a woman can prevent, save doing whatever we can to keep ourselves from becoming highly aroused, which doesn't sound like such a good deal to me, particularly if you're going to be having any kind of sex. Even though I hear that you're not feeling comfortable with this aspect of your sexual response, sex isn't going to feel as good when we're less aroused: the more excited we are, the better it feels. If, however, your partner is being particularly aggressive with her hands or fingers, that might cause additional swelling, so if you like, you can try a few times where she's a little more gentle to find out if that helps and feels better for you during and afterwards.

That should subside, however, within a few hours of sexual activity or arousal, if not in a shorter period of time. If and when it doesn't, it might be because orgasm wasn't reached, so that vasocongestion (what men call "blue balls," but it happens to women, too) sticks around and can start to feel painful. If and when that happens, rather than washing your genitals -- particularly if you're using fragranced or antibacterial washes, or washing inside your vagina, neither of which are healthy for your vagina -- your better bet is a cold compress, and/or a basic analgesic, like an aspirin, Tylenol or Ibuprofen.

In the off-chance that this isn't about arousal, and is ONLY happening after sex is over, the only other possibility would be that it's an allergic reaction to something: maybe a hand creme your partner uses, the soap she's washing with, the kind of lube you're using, et cetera. If you want to check and see if it's that. Next time have her use latex or nitrile gloves for the manual sex and a hypoallergenic lube (Pink lube or Emerita lube are both good in that department), and see if you have the same response. If you do not, then it may be an allergy or sensitivity we're talking about, so what you'll want to do is either keep to gloves (they usually feel better with manual sex anyway), or start narrowing down what the allergy is through trial and error, by her one day not using a given hand creme, the next using a different soap to wash up with, what have you.

But if it turns out not to be an allergy, and instead your normal sexual response, what I'd encourage you to do is to just try to get a bit more comfortable with it. If it's a psychological discomfort, know it's a normal sexual response, just like reaching orgasm is normal, feeling your heart rate elevate is normal, just like self-lubricating is normal. If it's physical, then set a cool compress or ice pack near the bed before sex begins that you can use right afterwards if you like. If it's continuing long after sex is done and you're not reaching orgasm during sex, then you two might try some new things to see about getting you to orgasm.

To sum up your plan of action?
1. May as well check for a possible allergy first to rule that out, or discover that's an issue. If so, figure out what the allergy is to and get rid of that agent. If you two can't figure it out yourselves, you could see your gynecologist and get some professional help in finding the culprit.
2. If it's not an allergic response, try having your partner adapt what she's doing to see if some or all of the swelling just isn't a bit much.
3. If it's none of those things, accept that this is part of your normal sexual response simply because you're getting very aroused and enjoying yourself, which is obviously a good thing. If you find it uncomfortable afterwards, treat the issue with a cool compress and/or an analgesic.

Here are some links for you with a little more information: