Surgical needle device comprising: a surgical needle (106, 174, 212, 252, 292) having a lumen (126, 224, 264, 306), wherein the lumen (126, 224, 264, 306) has an inner wall (136, 222, 262, 304), a removable mandrel (108, 170, 214, 258, 296) suitable for being located within said surgical needle (110, 172, 216, 254, 294), said removable mandrel (108, 170, 214, 258, 296) to be moved in and moved out of said surgical needle (106, 174, 212, 252, 292); and a medical positioning system sensor (110, 172, 216, 254, 294) located at the tip of said removable mandrel (108, 170, 214, 258, 296), said MPS sensor (110, 172, 216, 254, 294) to be coupled with an MPS (102, 162), said MPS (102, 162) to be coupled with an electromagnetic field generator (104, 166), said electromagnetic field generator (104, 166) generating an electromagnetic field, said MPS sensor (110, 172, 216, 254, 294) producing an output according to said electromagnetic field, said MPS (102, 162) determining the position of said tip of said removable mandrel (108, 170, 214, 258, 296) in a coordinate system respective of said MPS (102, 162), according to said output of said MPS sensor (110, 172, 216, 254, 294), said MPS (102, 162) producing an indication respective of said position, to enable navigation of said surgical needle (106, 174, 212, 252, 292) toward a target organ, characterized in that said MPS sensor (110, 172, 216, 254, 294) is firmly coupled with the tip of said removable mandrel (108, 170, 214, 258, 296) such that said MPS sensor (110, 172, 216, 254, 294) seals against said inner wall (136, 222, 262, 304) of said lumen (126, 224, 264, 306), whereby the entrance of undesired bodily substances into the surgical needle (106, 174, 212, 252, 292) is blocked, while said surgical needle (106, 174, 212, 252, 292) is being advanced toward said target organ. a surgical needle (106, 174, 212, 252, 292) having a lumen (126, 224, 264, 306), wherein the lumen (126, 224, 264, 306) has an inner wall (136, 222, 262, 304), a removable mandrel (108, 170, 214, 258, 296) suitable for being located within said surgical needle (110, 172, 216, 254, 294), said removable mandrel (108, 170, 214, 258, 296) to be moved in and moved out of said surgical needle (106, 174, 212, 252, 292); and a medical positioning system sensor (110, 172, 216, 254, 294) located at the tip of said removable mandrel (108, 170, 214, 258, 296), said MPS sensor (110, 172, 216, 254, 294) to be coupled with an MPS (102, 162), said MPS (102, 162) to be coupled with an electromagnetic field generator (104, 166), said electromagnetic field generator (104, 166) generating an electromagnetic field, said MPS sensor (110, 172, 216, 254, 294) producing an output according to said electromagnetic field, said MPS (102, 162) determining the position of said tip of said removable mandrel (108, 170, 214, 258, 296) in a coordinate system respective of said MPS (102, 162), according to said output of said MPS sensor (110, 172, 216, 254, 294), said MPS (102, 162) producing an indication respective of said position, to enable navigation of said surgical needle (106, 174, 212, 252, 292) toward a target organ, characterized in that said MPS sensor (110, 172, 216, 254, 294) is firmly coupled with the tip of said removable mandrel (108, 170, 214, 258, 296) such that said MPS sensor (110, 172, 216, 254, 294) seals against said inner wall (136, 222, 262, 304) of said lumen (126, 224, 264, 306), whereby the entrance of undesired bodily substances into the surgical needle (106, 174, 212, 252, 292) is blocked, while said surgical needle (106, 174, 212, 252, 292) is being advanced toward said target organ.