A device for positioning a needle in an ultrasound-guided treatment or examination is disclosed. The device may include a main body portion attached to an ultrasound probe, an adjustable arm member attached to the main body member, and a needle mount attached to the arm member. The probe casts an ultrasound beam to identify a target portion of a material. The arm member is adjustable to position a needle attached to the needle mount in a desired position relative to a desired point of entry into the material. The needle mount is adjustable to position the needle at a desired insertion angle into the material. The needle may be inserted into the material to deliver medication in a vicinity of the target portion of the material, or extract fluid or a material sample from the target portion of the material. A system and method employing the device are also disclosed.