"Where did the condom go?"
"Uh...I dunno. I think we lost the condom inside my vagina."
Has this ever happened to you?
This happened to a friend of mine just last week.
She dug around inside her vagina. He dug around inside her vagina. She jumped up and down. She did pilates. She ended up going to Planned Parenthood to have the condom removed.
Where did it go? Well, you can't actually "lose" anything inside your vagina, because it is only a few inches long and the cervix is at the far end, blocking entrance into the uterus. However, the cervix is at the top and to the side of the vaginal canal, and things can get tucked next to the cervix. If a condom is compacted and warmed to body temperature, it can feel a lot like the folds of the vagina when digging around. But I think just knowing that a condom can't actually get lost inside the vagina is helpful.
What to do if this happens to you?
Put one or two fingers inside your vagina as far as possible and gently feel around for the rim of the condom. Be patient and not frantic. Or, sit on the toilet or squat down and bear down like you're going to the bathroom. If nothing works to remove it, then do go see a medical professional to have it removed.
How to avoid?
Condoms do come in different shapes and sizes, so you can ensure a snug but comfortable fit. Make sure it it rolled all the way to the bottom of the penis. If you are using lube inside the tip for added pleasure, make sure it's only about a dime-sized amount. Hold onto the condom when pulling out. And if the penis is getting softer at any time, be aware that the condom could slip off!
What are the potential consequences?
If there was an exchange of fluids, which is likely in this situation (i.e., precum, semen, vaginal secretions, blood) then the risk for transmitting STDs/STIs is present. The skin-to-skin contact also allows for transmission of certain STDs/STIs such as herpes or HPV. As well, if you are using condoms for birth control, having precum or semen in your vagina is risky.
There is emergency contraception that can reduce the risk of pregnancy for up to 120 hours after intercourse. This is basically a very high dose of birth control pills, so potentially expect some side effects for a couple days. As far as STDs/STIs, pay attention for anything different in odor, discharge, or appearance around your genitals. However, many STIs do not have visible symptoms, so get yourself checked out!