VERY WORRIED

Hi all I had an operation 4 weeks ago to remove my right tube as i had an ectopic pregnancy. I was told by a doctor to do a test in 4 weeks so I done one and it has come back positive!! me and my partner have had sex however we used protection. I do not want to be pregnant as i am so scared it will happen again. and I don't know how I would get a positive 4 weeks after? has this happened to anyone. I will be calling consultant tomorrow but he isn't there today