My girlfriend lives in accra Ghana and wants $500 to visit a hospital so she can have tests done and get some medication I think it is an excessive amount for a hospital visit

This screams SCAM. The U.S. embassy even mentions this sort of thing (need for money) on their web site -- Romance Scams | Embassy of the United States Accra, Ghana

Do not send money!

Yes, it is excessive. Most likely she won't use it for the hospital as there is nothing wrong with "her." You are being scammed.

Have you ever met her? No? She is scamming you. She will want money for a passport...a visa...a plane ticket....she will want money for her sick mother....she will keep wanting money until you have no more to give. Oh and...she is probably not even a she except for the times you talk on the phone.

The women who do these scams are married or have boyfriends or male relatives who set up the connections with men all over the world, as many hundreds as they can talk to in one day. Actually it's MEN you are dealing with - she's just the pawn to reel you in.