I'm having a CD21 blood test today and I'm a bit nervous about it. Anyone else had it, or can tell me what they're looking to find, or how long results normally take? I know I should have asked the doctor, but I didn't think of the questions until I'd left the surgery, and the nurse taking the blood is the phlebotomy nurse, not a fertility expert.
CD21 bloods are looking primarily for progesterone levels which indicate whether you've ovulated that month. My GP told me that they should be done 7 days before af starts but, in reality, they can't predict the start of af unless you're regimental in your cycle at a set length. If your cycle is much longer than 28 days you should time your d21 bloods for later in your cycle (so if your cycle is usually 42 days, then bloods should be done on d35)
Results, if the tests are done at your GP surgery, should be available within 5 working days - though much of at depends on when the surgery review them and sign them off for you to be told.