If you can plan ahead, get an emla patch from your chemist, turn up 45 minutes before he is due for the test, and ask them where to put it.
When the test is being done, you might find it easiest to sit him in your lap, facing outwards. Put one arm, around his body like you are giving him a cuddle (which will keep his arms down, or whichever arm they aren't using, anyway) and the other around his upper body or forehead, depending on how much he will struggle. Sing to him, talk to him quietly. Try hard not to cry, and I sympathise - I do this for a living and I had tears in my eyes when we had to get Molly tested. One nurse will probably hold the arm out straight while the other one takes the blood.
Oh, and the heel ***** thing - the reason they don't do it after the baby is a few months old is that the results don't come out right for some of the tests.
Mine had a blood test earlier this year, got all the coaching on what they were going to do, what she should do etc etc.
Unfortunately she decided several seconds *after* the needle went in and the doc was halfway through getting blood that the needle going in hurt, so she did an overdramatic jump complete with exaggerated facial expression, needle comes out, blood goes everywhere, doc goes into panic mode.
Started again on the other arm with me holding her down, worked this time.
Reminded me a bit of the time she got her nose cauterised - screamed the house down when the cauterising thingy was an inch from her nose but didn't even blink once it was actually in use. Needed two of us to hold her still and she hadn't even been touched. The doc looked like she was going to wring DD's neck.
So watch out for kids doing stuff you don't expect ...
He had it done this afternoon and he was a little star.
We got the emla patch and it worked a treat - he didn't flinch when it went in and he barely moved while they were doing it. The nurses doing it tried to distract him but he was way too interested in seeing his blood being bottled for the distraction to work.
Bookmarks