Have an NT result of 4.6 mm. Need help deciding if I should opt for CVS instead of waiting for blood test result.

I'm 37 years old and am 11 wks and 2 days pregnant.  I just got the Nuchal Translucency test and it was 4.6 mm!  My blood test result won't come in until next week, and by that time, it may be too late to get CVS.  I'm wondering if I should wait until the blood test or go straight for CVS.  I've read some posts that said their doc recommended that they go straight to CVS at 5.0mm.  I wonder if 4.6 mm is still the same emergency.  Thanks!