A medical system, comprising: an implantable access port configured to be implanted into a subject, the access port including an implantable access port body and at least one implantable access port needle; wherein the at least one needle comprises a needle shaft with a needle lumen, and a first needle tip which is connectable to and removable from the needle shaft; wherein the needle lumen is closed by the first needle tip when the first needle tip is connected to the needle shaft; wherein the at least one needle is concealable inside the access port body in a concealed position and is exposable outside the access port body in an exposed position; wherein the at least one needle is arranged within the access port body to penetrate outwardly through skin of the subject from within the subject when the access port is implanted in the subject; a transfer device comprising a fluid infusion and/or extraction apparatus couplable to the at least one needle of the access port, the fluid infusion and/or extraction apparatus configured to transfer a fluid to and/or from the subject through the access port when coupled with the at least one needle of the access port; and wherein the fluid infusion and/or extraction apparatus is configured to form a closed treatment system with the access port, wherein the fluid infusion and/or extraction apparatus includes a fluid flow passage configured to transfer the fluid to and/or from the subject through the access port; and wherein the fluid infusion and/or extraction apparatus is configured to receive the at least one needle with the first needle tip connected to the needle shaft, such that the first needle tip and the needle shaft are within the fluid flow passage; characterized in that the fluid infusion and/or extraction apparatus is configured to remove the first needle tip from the needle shaft while the first needle tip and the needle shaft are within the fluid flow passage by rotating the first needle tip or by applying a pulling force to the first needle tip. an implantable access port configured to be implanted into a subject, the access port including an implantable access port body and at least one implantable access port needle; wherein the at least one needle comprises a needle shaft with a needle lumen, and a first needle tip which is connectable to and removable from the needle shaft; wherein the needle lumen is closed by the first needle tip when the first needle tip is connected to the needle shaft; wherein the at least one needle is concealable inside the access port body in a concealed position and is exposable outside the access port body in an exposed position; wherein the at least one needle is arranged within the access port body to penetrate outwardly through skin of the subject from within the subject when the access port is implanted in the subject; wherein the at least one needle comprises a needle shaft with a needle lumen, and a first needle tip which is connectable to and removable from the needle shaft; wherein the needle lumen is closed by the first needle tip when the first needle tip is connected to the needle shaft; wherein the at least one needle is concealable inside the access port body in a concealed position and is exposable outside the access port body in an exposed position; wherein the at least one needle is arranged within the access port body to penetrate outwardly through skin of the subject from within the subject when the access port is implanted in the subject; a transfer device comprising a fluid infusion and/or extraction apparatus couplable to the at least one needle of the access port, the fluid infusion and/or extraction apparatus configured to transfer a fluid to and/or from the subject through the access port when coupled with the at least one needle of the access port; and wherein the fluid infusion and/or extraction apparatus is configured to form a closed treatment system with the access port, wherein the fluid infusion and/or extraction apparatus includes a fluid flow passage configured to transfer the fluid to and/or from the subject through the access port; and wherein the fluid infusion and/or extraction apparatus is configured to receive the at least one needle with the first needle tip connected to the needle shaft, such that the first needle tip and the needle shaft are within the fluid flow passage; characterized in that the fluid infusion and/or extraction apparatus is configured to remove the first needle tip from the needle shaft while the first needle tip and the needle shaft are within the fluid flow passage by rotating the first needle tip or by applying a pulling force to the first needle tip. wherein the fluid infusion and/or extraction apparatus is configured to form a closed treatment system with the access port, wherein the fluid infusion and/or extraction apparatus includes a fluid flow passage configured to transfer the fluid to and/or from the subject through the access port; and wherein the fluid infusion and/or extraction apparatus is configured to receive the at least one needle with the first needle tip connected to the needle shaft, such that the first needle tip and the needle shaft are within the fluid flow passage; characterized in that the fluid infusion and/or extraction apparatus is configured to remove the first needle tip from the needle shaft while the first needle tip and the needle shaft are within the fluid flow passage by rotating the first needle tip or by applying a pulling force to the first needle tip.