Accuracy of allergy testing using blood work

[SaraFR]

I'm nursing DS3 now so I'll have to keep this short and add more later.

We got my little nursling (11 1/2 months old) tested for the main food allergies using blood work as ordered by the ped.

He came back negative for all the ones tested. We know that as of April/May this same child seemed "rashier" (his skin in general tends to get easily rashy) and was doing this gag like action with vomit like stuff coming out (sorry if that made zero sense or was gross for those who understood it) after I ate dairy and he nursed some hours later. He had this reaction through me, he didn't even eat it directly. I'm hesitant to trust the results. How accurate is this type of testing?

[lil_miss_understood]

There are a few different types of blood tests, I believe, many done by different laboratories. Each one is unique in it's accuracy level. Your doctor should have told you what the "rate of error" was for your particular test and lab.
However, my allergist has always told me that reactions trump results- meaning that if your child reacts to it but doesn't have a test result that says he's allergic, treat it as an allergy regardless. So, if you notice that your child is reacting to dairy through your bm, you should take it out of your diet and not expose him to it directly.