An ultrasound system for tracking movement of an object received in a body, comprising: an ultrasound transducer unit having an imaging field of view, FOV; a motion detector adapted to detect movement of the ultrasound transducer unit relative to the body; and a controller, operatively coupled with the ultrasound transducer unit and the motion detector, and configured to: detect and track movement of said field of view over time relative to the body using data from the motion detector, detect and track positions over time of the tracked object within the field of view, and generate an estimation of a direction of motion of the object through the body over time, based on a history of the detected object positions within the FOV over time, and based on the detected and tracked movement of said FOV relative to the body over time; communicate with i) an ultrasound sensor incorporated in the object to be tracked, the ultrasound sensor for detecting ultrasound signals transmitted by the ultrasound transducer unit into the body or ii) an ultrasound emitter incorporated in the object to be tracked, the ultrasound emitter for emitting ultrasound signals within the body for detection by the ultrasound transducer unit, for use in tracking the object position; track the position of a designated point on the object, for example a tip of the object; and to determine a range or a span of possible current positions of said designated point of the object within the field of view, based on a known distance between said designated point and the respective i) ultrasound sensor, or ii) ultrasound emitter, incorporated in the object, and based on the tracked positions of the object. an ultrasound transducer unit having an imaging field of view, FOV; a motion detector adapted to detect movement of the ultrasound transducer unit relative to the body; and a controller, operatively coupled with the ultrasound transducer unit and the motion detector, and configured to: detect and track movement of said field of view over time relative to the body using data from the motion detector, detect and track positions over time of the tracked object within the field of view, and generate an estimation of a direction of motion of the object through the body over time, based on a history of the detected object positions within the FOV over time, and based on the detected and tracked movement of said FOV relative to the body over time; communicate with i) an ultrasound sensor incorporated in the object to be tracked, the ultrasound sensor for detecting ultrasound signals transmitted by the ultrasound transducer unit into the body or ii) an ultrasound emitter incorporated in the object to be tracked, the ultrasound emitter for emitting ultrasound signals within the body for detection by the ultrasound transducer unit, for use in tracking the object position; track the position of a designated point on the object, for example a tip of the object; and to determine a range or a span of possible current positions of said designated point of the object within the field of view, based on a known distance between said designated point and the respective i) ultrasound sensor, or ii) ultrasound emitter, incorporated in the object, and based on the tracked positions of the object. detect and track movement of said field of view over time relative to the body using data from the motion detector, detect and track positions over time of the tracked object within the field of view, and generate an estimation of a direction of motion of the object through the body over time, based on a history of the detected object positions within the FOV over time, and based on the detected and tracked movement of said FOV relative to the body over time; communicate with i) an ultrasound sensor incorporated in the object to be tracked, the ultrasound sensor for detecting ultrasound signals transmitted by the ultrasound transducer unit into the body or ii) an ultrasound emitter incorporated in the object to be tracked, the ultrasound emitter for emitting ultrasound signals within the body for detection by the ultrasound transducer unit, for use in tracking the object position; track the position of a designated point on the object, for example a tip of the object; and to determine a range or a span of possible current positions of said designated point of the object within the field of view, based on a known distance between said designated point and the respective i) ultrasound sensor, or ii) ultrasound emitter, incorporated in the object, and based on the tracked positions of the object.