Blood test results - help please!

I am 5w 4d pregnant and saw the doctor last thurs (4w6d) and was told to get a blood test and also gave me the form for an early dating scan to have at 8 weeks and then go back to her when she gets the results. 
​She said that she would call me if there was something to know about the blood test but otherwise I wouldn't hear from her til after the scan.
​I did the blood test at 5w1d and just got a call from the doctor saying I have to make an appointment to see her to discuss the results. 
​Can anyone tell me what this means? What can they tell from those bloods? Is it likely to be bad news?