A bone marrow biopsy is much more painful than an aspiration, which is what our physicians do. There is variability, but my own experience was a fleeting cramp (3 out of 10), that lasted about 15 seconds. I have been many of our collections, and that's typical. A local anesthetic is used, and mostly what you feel is pressure. You don't see anything, because the draw is on your lower back. Our physicians often prescribe an oral pain killer, and sometimes something to relax you. However, a surprising number of our clients decline both, typically because they want to drive home. The procedure takes about 15 minutes from laying down on your side, to standing up again. You are usually in and out within 1 hour.
I found it to be quite painful for about 10 minutes (the length of the aspiration procedure). Once the procedure is over, I would describe the sensation as "annoying, not particularly painful" for about 48 hours.
I've had an aspiration done. It was mostly just uncomfortable 3/10, with a few moments of pretty sharp pain more like a 6/10. However, those moments were brief and it was totally fine afterwards.
I also turned down some more potent painkillers beforehand, so if I had taken those instead of just the local anesthetic, it likely would have been less unpleasant.
Mild discomfort followed for a few days and within a week or so I had forgotten about it.
The speed of extraction helps determine the intensity. If it's very slow it's a mild sharp pain - difficult to describe otherwise. If it's extracted too quickly that mild sharpness becomes super intense. It's an interesting experience.
The discomfort is difficult to describe. I best describe it as a cramp. We believe that the negative pressure is in part to blame, and we have filed IP on a possible solution.
I believe that the negative pressure/vacuum is known to be the cause. One obvious solution would be to replace that pressure with a solution, probably your own plasma or similar - and then you'd just need to determine the best technology to apply for the system to allow for equilibrium..