They have them in the US, I think they might be called IUC. They probably are more popular in the UK because if you had to pay for them (like you do in the US), you have to pay out about $500 up front. Which probably seems like a lot to people even though it lasts 5 years. In the UK, all contraception is free, so its more of an appealing choice. I have an American friend who was over here studying for a year and the first thing she did was get one fitted when she got here because that way she could get one for free.