A system for use in conjunction with an ultrasound device (10; 110; 310; 410) comprising: a guide cartridge (130; 530; 630; 730; 830; 930) configured for slidable conformation with a guide rail (43, 45; 182, 183; 443, 445; 453, 455; 463; 473), the guide rail (43, 45; 182, 183; 443, 445; 453, 455; 463; 473) defining a guide track (140; 540; 640; 740; 840; 940) for the guide cartridge (130; 530; 630; 730; 830; 930), wherein the guide cartridge is associated with a hub (132; 532); and a subdermal device (39; 139; 239; 439; 839; 939) configured to be retained by the hub (132; 532), such that upon assembly of the system, the guide cartridge (130; 530; 630; 730; 830; 930), the hub (132; 532), and the retained subdermal device (39; 139; 239; 439; 839; 939) slide together as a single unit along the guide track (140; 540; 640; 740; 840; 940); characterized by a target (48; 248; 448; 458; 468; 478; 488) for a detection system, the target being detectable by a detector of the detection system, the detection system being configured for locating a tip of the subdermal device (39; 139; 239; 439; 839; 939), wherein the target (48; 248; 448; 458; 468; 478; 488) is associated with the hub (132; 532), with the subdermal device (39; 139; 239; 439; 839; 939) or with the guide cartridge (130; 530; 630; 730; 830; 930); and by a sterilizable shield (20; 120; 220; 520) that is removably attachable to an ultrasound transducer (10; 110), wherein the guide rail (43, 45; 182, 183) is defined on a surface of said sterilizable shield (20; 120; 220; 520), or by a shell (350; 450) that is removably attachable to an ultrasound transducer (10; 110), wherein the guide rail (443, 445; 453, 455; 463; 473) is defined on a surface of said shell (350; 450). a guide cartridge (130; 530; 630; 730; 830; 930) configured for slidable conformation with a guide rail (43, 45; 182, 183; 443, 445; 453, 455; 463; 473), the guide rail (43, 45; 182, 183; 443, 445; 453, 455; 463; 473) defining a guide track (140; 540; 640; 740; 840; 940) for the guide cartridge (130; 530; 630; 730; 830; 930), wherein the guide cartridge is associated with a hub (132; 532); and a subdermal device (39; 139; 239; 439; 839; 939) configured to be retained by the hub (132; 532), such that upon assembly of the system, the guide cartridge (130; 530; 630; 730; 830; 930), the hub (132; 532), and the retained subdermal device (39; 139; 239; 439; 839; 939) slide together as a single unit along the guide track (140; 540; 640; 740; 840; 940); characterized by a target (48; 248; 448; 458; 468; 478; 488) for a detection system, the target being detectable by a detector of the detection system, the detection system being configured for locating a tip of the subdermal device (39; 139; 239; 439; 839; 939), wherein the target (48; 248; 448; 458; 468; 478; 488) is associated with the hub (132; 532), with the subdermal device (39; 139; 239; 439; 839; 939) or with the guide cartridge (130; 530; 630; 730; 830; 930); and by a sterilizable shield (20; 120; 220; 520) that is removably attachable to an ultrasound transducer (10; 110), wherein the guide rail (43, 45; 182, 183) is defined on a surface of said sterilizable shield (20; 120; 220; 520), or by a shell (350; 450) that is removably attachable to an ultrasound transducer (10; 110), wherein the guide rail (443, 445; 453, 455; 463; 473) is defined on a surface of said shell (350; 450). <EOS>