The present invention relates to a particularly convenient medium for providing contrast enhancement and/or distension of the subject body or organ cavity during imaging, radiographic, visualization, or other similar medical examinations, including ultrasound, endoscopic examinations, MRI, x-ray, hystero-salpingograms, CT scans, and similar procedures. The present invention provides the contrast enhancement and/or distends the body or organ cavity without constant leakage of the medium or the resulting need to constantly or repeatedly infuse additional medium. The medium is designed to have sufficient viscosity or consistence initially to remain in the body or organ cavity for a time generally sufficient to complete the procedure, and then to facilitate easy removal or expulsion from the cavity, preferably by liquefying or losing viscosity. The phase or viscosity change may be triggered by a variety of factors that liquefy or otherwise facilitate easy removal or expulsion of the composition from the cavity.