Rectal hydration! Interesting! ;)
Far more common than proctoclysis -and than subcutaneous infusion as well- IV fluids are used from wound cleansing [1] to intraosseous infusion [2]. But you are right; as a general reference to the infusion "bags or bottles" those sueros y fluidoterápicos might be better named
infusion fluids / infusion fluids and solutions; se trata de productos preparados para uso endovenoso pero ciertamente no son de administración
exclusiva por esta vía. Nevertheless, the general denomination of IV fluids (and solutions) is not only common but understandable, in spite of them not being necessarily IV-infused.
Thanks for thinking it over, Helena!
[1] Wound cleansing is conducted with at least 100ml of sterile normal saline (NS) or sterile water container"
https://www.google.es/url?sa=t&source=web&rct=j&url=https://...[2] Any intravenous fluid, blood products or routine resuscitation drugs can be administered through the IO route.
https://www.sciencedirect.com/science/article/pii/S2211419X1...