When will Trump bring back leeching?
They're already back. They're used in limb reattachment surgery post-operative treatment.
When limbs are reattached the arteries work well right away but the veins not so much. So they have poor circulation and inadequate oxygenation, especially at the finger and toe tips. This can lead to further cell death, infection, and transplant failure.
Leeches applied to the extremities of the limbs can pull out enough blood and bring in fresh to keep more cells alive and bring more infection-fighting white cells to the area. And leeches do little damage other than draining blood, and provide their own surgical tools and anaesthetic. (It's in their evolutionary interest to not bother the victim into pulling them off while they're feeding, and not leaving wounds that would make him tend to avoid the location later.) So raised-sterile leeches are used, with substantial improvement in reattachment success rates.