STP - standardní punkce (normally written in English as the "standard puncture and aspiration" method)
"Bone marrow was collected from the iliac crest as described previously (Brennan et al., 2014), by standard puncture and aspiration into heparinized syringes"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7137087/

This abbreviation may appear on request notes for bone marrow cytology examinations along with TREP (= trephine biopsy)
https://www.fnhk.cz/fs3412/zadankakostni-dren.pdf

"For the bone marrow aspiration, a thin needle is used to remove a sample of fluid (aspirate) from the bone marrow – usually from the pelvic bone, but sometimes from the chest. A trephine biopsy, sometimes done with a second needle, removes a small piece of bone with the marrow inside."
https://www.cancercouncil.com.au/myeloma/diagnosis/tests/bon...