Focused ultrasound can be used to close blood vessels, with the potential to provide a non-invasive treatment of internal bleeding or a means of cutting off the blood supply to specific structures, such as tumors.
The heat generated by focused ultrasound can be used for hemostasis (e.g. to control internal bleeding) by thermally closing wounded blood vessels1,2. One preclinical study found that focused ultrasound was able to achieve hemostasis in a punctured femoral artery in all of their test animals with durable, long-term results3. Examination of the treated region has shown that the soft tissue surrounding the blood vessel hardens due to adventitia coagulation, creating a seal4. This mechanism has many clinical applications including stopping liver hemorrhage, which can be difficult to treat and is a leading cause of death in patients who have had liver trauma5.
Alternatively, it has been proposed that the mechanical effects of ultrasound can cause damage to vessel walls which exposes tissue factors. These tissue factors cause a cascade of biological reactions that result in the formation of a blood clot and eventual occlusion of the blood vessel1,6. Furthermore, blood vessel occlusion with focused ultrasound has potential for the treatment of esophageal and gastric varices, arteriovenous malformations, and varicose veins without the risk of distant clot formation or the use of a catheter1,7,8. It can also provide a noninvasive method to cut off the blood supply to benign or malignant tumors, effectively starving them of vital nutrients and making them more vulnerable to other treatments2,9.
 C.-P. Jiang, M.-C. Wu, and Y.-S. Wu, “Inducing occlusion effect in Y-shaped vessels using high-intensity focused ultrasound: finite element analysis and phantom validation.,” Comput. methods Biomech. Biomed. Eng., vol. 15, no. 4, pp. 323–332, May 2012.
 Zderic V, Keshavarzi A, Noble ML, Paun M, Sharar SR, Crum LA, et al. Hemorrhage control in arteries using high-intensity focused ultrasound: A survival study. Ultrasonics. 2006;44:46–53.
 Vaezy S, Martin R, Yaziji H, Kaczkowski P, Keilman G, Carter S, et al. Hemostasis of punctured blood vessels using high-intensity focused ultrasound. Ultrasound Med. Biol. 1998;24:903–10.
 Vaezy S, Martin R, Schmiedl U, Caps M, Taylor S, Beach K, et al. Liver hemostasis using high-intensity focused ultrasound. Ultrasound Med. Biol. 1997;23:1413–20.
 Poliachik SL, Chandler WL, Mourad PD, Ollos RJ, Crum LA. Activation, aggregation and adhesion of platelets exposed to high-intensity focused ultrasound. Ultrasound Med. Biol. 2001;27:1567–76.
 Hynynen K, Colucci V, Chung A, Jolesz F. Noninvasive arterial occlusion using MRI-guided focused ultrasound. Ultrasound Med. Biol. 1996;22:1071–7.
 Zhou Y, Zia J, Warren C, Starr FL, Brayman AA, Crum LA, et al. Targeted Long-Term Venous Occlusion Using Pulsed High-Intensity Focused Ultrasound Combined with a Pro-Inflammatory Agent. Ultrasound Med. Biol. 2011;37:1653–8.
 Goertz DE. An overview of the influence of therapeutic ultrasound exposures on the vasculature: High intensity ultrasound and microbubble-mediated bioeffects. Int. J. Hyperthermia. 2015;31:134–44.
Read more about blood vessel coagulation on PubMed.