Connector for a dialysis port

A dialyzer in combination with a connecting device comprising:

• a dialyzer having a dialysate port;
• and
• a connector configured to connect said dialysate port of said dialyzer to a dialysate-carrying line, said connector having a first lumen and a second lumen passing therethrough, a first end of the connector surrounding the first lumen and configured to accommodate the dialysate port in the first lumen, a second end of the connector surrounding the second lumen and configured for being connected to the dialysate-carrying line, said connector first end having two opposite recesses with a shift element accommodated in said recesses such that the shift element is displaceable between a first position and a second position perpendicular to the direction of the first lumen in the connector first end, said shift element having a first opening which does not constrict the first lumen in the first position and a second opening which is connected to the first opening in the direction of shifting and which constricts the first lumen in the direction of the opposite recesses in the second position, the first opening having a round shape and the second opening having an elongated border so that an overall shape of said first and second openings together is that of a keyhole, said shift element in the second position narrowing the first lumen so that the connector with the shift element is placed on the dialysate port in the first position and, when the shift element is moved into the second position, the connector is locked on the dialysate port through engagement of the shift element behind an undercut on said port, said undercut having a slope inclined toward a connection end of said port, the elongated border of the second opening having a wall thickness that tapers with a corresponding slope toward the opening to have a form-fitting engagement with the slope on the undercut of said dialyzer port when the connector is secured to the port.