The invention relates to a connection assembly for directing a medical liquid that includes a connector through which a medical liquid can be delivered, an attachment part that can be connected to connector and is attachable to a delivery device for delivery of a medical liquid through the connector, and has an opening in which the connector engages with the attachment part, and a sealing element for sealing the transition between the connector and the attachment part. The sealing element can be inserted into the opening of the attachment part in an insertion direction in such a manner that the sealing element is held between the attachment part and the connector with the attachment part attached to the connector.
