A centering device for use with an ultrasound probe and the combination of that device and the probe is disclosed. The probe has a distal portion in which an ultrasound emitter is located. The emitter is arranged to be rotated about the central longitudinal axis of the probe without rotating the probe itself to provide ultrasound images of a patient extending 360 degrees about that axis. The centering device includes an inner sheath and an outer sheath surrounding the inner sheath to form a space therebetween. The space is inflatable by a liquid to expand to form a cylindrical annularly shaped chamber surrounding the distal portion of the probe, thereby centering the distal portion of the probe within the patient.
