I've had 7 BMBs - each one was a different experience. The first was done by Dr. Siddhartha Mukherjee - the author of the Pulizer Prize-winning book "The Emperor of all Maladies: an autobiorgraphy of cancer." I had NO sedation or anti-anxierty drug. He talked me through it, and my husband held my hand. The lidocaine was ALMOST the worst part - except for when he withdrew the aspirate, but that pain stopped immediately when he stopped and was very quick. This was was done with me in prone. They asked me to lie flat for 1/2 hour afterwards, but after that I had no pain - only some discomfort when sitting in certain positions for about a week or so afterward.
The second was done when I went into Columbia Presbyterian for my first induction (I have AML), and they had me in side-lying. What I didn't know at first, was that my MD let his Fellow start the procedure, (I was lying on my side holding my husband's hand with my eyes screwed shut), and I was in AGONY. I told him he had to stop - and at that point my MD took over and it was bearable.
For the THIRD one (after induction) I asked for a good whallop of pain meds, and they gave me morphine (I was in-patient still), and I had forbidden the Fellow (who was a nice guy) to be in the room. I had a couple of seconds of pain, but that was it. The morphine kept me quite happy.
The FOURTH one was done out-patient and will a drill (it sounds horrible - like they are drilling to screw something into a wall), but it's faster. That time I had an oral morphine tablet and a Valium in advance. There was one moment when I had a horrible burning sensation in my groin (shouldn't have happened, the nerve responsibe is supposed to run anterior (in front of) the iliac crest - which is where they are digging for "gold". As soon as I said "stop", the MD did and the sensation went away never to return;
The FIFTH was similar to number 4.
The SIXTH was done at Memorial Sloan Kettering by a final year Fellow. I did take a hydrocodone and a valium in advance, but I swear I never felt anything after the lidocaine shots. (BTW, I've come to the conclusion that is't less painful when they do with with the patient prone.) I never had any pain or discomfort afterwards either.
The SEVENTH happened yesterday by the next "final year Fellow". This time I only took a Valim, because I'm feeling nuts enough on the antifungal, antiviral and antibiotic cocktail they have me on. Again, only the lidocain hurt. I do have some discomfort now if I sit in certain positions (which put pressure on the site). I was told to keep the bandage dry for 48 hours. (I have Aquaguard patches for my PICC in any case.)
I generally chat with the staff while they do the procedure. It helps my nerves. Good luck.