Allergy and Other Risks of Ultrasound Gel: Recognition and Alternative Coupling Agents

Abstract

We recently encountered a patient who required urgent leg venous ultrasound. The patient warned us of a previous severe allergic reaction to ultrasound gel, an uncommon problem without a defined prevalence (according to our searches for literature on PubMed, Google Scholar, and uptodate.com). The reaction was so severe that he permitted ultrasound only if an alternative agent could be used. We recalled both that allergy to gel is possible and that mineral oil could be used as a coupling agent in such cases and purchased a bottle on the spot while the patient waited. The clinical flexibility of switching to an alternative coupling agent turned out to be potentially life-saving because the patient was found to have an extensive deep venous thrombosis of the common femoral, femoral, deep femoral, popliteal, and gastrocnemius veins. This case report details this patient's course; reviews the potential adverse effects of ultrasound gel, proven and theoretical; demonstrates the excellent imaging characteristics of a large number of alternative coupling agents that we tested on our patient as well as another subject; and describes strategies for prevention and management of adverse effects. Although isolated case reports were found by literature search regarding use of alternative ultrasound coupling agents, we have found no review article or study evaluating as many agents as we have.