in a method and apparatus for the three - dimensional presentation of an examination region of a patient in the form of a 3d reconstruction image , a preoperatively acquired 3d image dataset of the examination region is employed in a medical procedure , datasets representing a number of 2d ultrasound images of the examination region are acquired , the preoperative 3d image dataset is updated using the datasets representing 2d ultrasound images , and the 3d reconstruction image is generated on the basis of the updated 3d image dataset .