Patent attributes
An extracorporeal circuit, which makes it possible to efficiently collect priming solution by displacing the priming solution with blood after the priming solution is fed to the extracorporeal circuit to prime the extracorporeal circuit, includes a circuit body including first and second tubes, a feed bag that feeds the priming solution, a blood reservoir in which a liquid is temporarily stored, a third tube that branches out from the middle of the first tube, and a collection bag which communicates with the third tube and into which the priming solution is collected through the third tube. After the priming solution is fed from the feed bag to prime at least a housing, when the priming solution in the housing is displaced by blood, the priming solution in the housing is transferred and collected in the collection bag due to a height difference between the liquid level and the collection bag.