Hi! Thank you for your query and welcome to HCM! If you were on your belly during that time, with your abdomen pressed against the massage table, you may have felt your abdominal aorta. Your prone position on the massage table along with the possible downward pressure from your masseuse who was working on your hip pain, may have somewhat compressed the abdominal aorta a bit, allowing you to feel the pulsations. The abdominal aorta is the major artery that brings oxygenated blood from your heart to the lower half of your body. Just like any artery, the abdominal aorta regularly pulsates in time with your heartbeat due to the immense pressure that the heart generates to allow for adequate blood circulation. There are disease conditions that can also affect this aorta. The weakening of the aortic wall due to atherosclerosis and hypertension can cause the abdominal aorta to balloon. This condition, called abdominal aortic aneurysm, can present with severe and persistent abdominal or lower back pain that can spread down to the hips and to the legs , a hard pulsating lump in the abdomen, nausea and vomiting. A simple visit to a physician who will examine you and may request for an abdominal ultrasound can be done to check for this condition if you experience any of the symptoms above. I hope I was able to address your concerns. If you have any further questions, please do not hesitate to contact me. Take care! Dr. Galera