For example, a stent consisting of polytetrafluoroethylene, which is placed on top of the vein so that it is not constricted. Performing an open abdominal surgery.
Because Internal stenting (common angioplasty and stenting) is subject to risks:
of compression of the stent - because the stent cannot be very durable due to the limitations of wire thickness.
and migration of the stent, in which case it is necessary to take anticoagulants for life
In opposite, External stent doesn't require to take anticoagulants at all, and can be very durable (high radial stability).
Any references to scientific papers are welcome.