Luna is right, you should not use a catheter THROUGH the "os" with unwashed fresh sperm. The os is the small opening of the cervix... basically the hole of the doughnut.
The reason being is that the centrifugation and swim-up washing techniques done on fresh sperm prior to IUI remove the postglandins. If you put the semen in the uterus without the washing and centrifugation, then the postglandins will cause cramping as well as decrease your chances of conception. The cramping can be intense and pretty painful, and they will definately screw with your odds of conception.
The "infection" and "possible death" and "embolism" you hear people frequently warn of are a little extreme, though. I say that because for at least a decade clinic IUI's were done with fresh unwashed sperm. There are lots of folks in the older generation who got pregnant with a fresh, unwashed sperm IUI.... but that is *not* done anymore. Eventually fertility dr's discovered the importance of a process called capication that sperm go through as they pass through the cervix... the cervix isn't just a gateway, it plays a huge role in preparation of sperm for successful fertilization. Sperm have a coating over them that nature provides to outsmart stuff like spermicides, etc. As the sperm pass through the cervix, there are enzymes and grooved channels the sperm go through that act to "wash" the coatings off the sperm as well as remove postglandins. This process is still mainly a mystery even to experts in this area, but they have tried to approximate the washing technique in the lab. Right now, IUI is not that much more statistically successful than plain old sex - even though they are getting the sperm straight up to the egg when the egg is released. I believe that IUI will someday be much more successful as the finer details are perfected... but till then, IVF is getting all the attention.
Anyway, blah blah blah.....
So what you can do is a fresh sperm ICI.... intervcervical insemination is simply depositing the sperm at the "os" or the entrance of the cervix. You would want to use a speculum and a catheter to do this, and only go into the cervix 1/4 of an inch. You are just dropping the swimmers off at the entrance of the cervix, because we know they need to go through the entire cervix route in order to be ready to do the job.
One more thing, some people use a tomcat cath for IVI... intervaginal insemination. As anyone who has stuck a syringe into their who-ha can tell you, size does matter! LOL! It just doesn't go the distance (even on me, who had never had penetrative sex and I am definately a "small" person). You can use the cath to deposit the sperm in the vagina, just more toward the back. The can be reassuring if run-out is a problem or if you just feel like the syringe is going into a black hole.
Warning: using a speculum creates leakage issues all its own, because the vagina spams as it is removed. You can practice all this with a syringe/cath/speculum with just water. Put a paper towel under your butt to see how leaky your technique will be. It is a good test run.
) so my method is probably ok success wise really. Just when I heard my friend had used a catheter I thought maybe it would be more successful. But it sounds complicated and I think I'll just stick to what I know 
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