An assembly of a retrieving element and a retrievable device of which one is a helical spring having an outer part of a winding which extends away from a main portion of the spring and thus is able to engage a thread of the other of the retrieving element and a retrievable device. The other of the retrieving element and a retrievable device may have an outer or an inner thread. The assembly may be used for retrieving devices temporarily positioned in a blood vessel of a person.
