Is it posible for your string on ur IUD marina to brake off?

I went to the restroom and notice when I wiped a spot of blood and a string. I don't have periods anymore since I got the IUD but spot alittle everyonce in awhile but never ever had a string come out. I wounder if its the string to the IUD or what. Plan on calling the doc in the morn but till then does anyone know what it could be????