Methods and devices for forming magnetic anastomoses between hollow bodies. End-to-side, side-to-side and end-to-end anastomoses can be created with or without a mechanical connection between the components. The anastomotic components may have various constructions and may be secured to a vessel in various manners, for example, magnetically, mechanically or adhesively. Also provided are alternative delivery devices, as well as devices for checking the position of a component on a loaded delivery device, and for checking the seal between a vessel and an anastomotic component secured thereto.