Auscultation of the abdomen in a consecutive series of 500 patients demonstrated that 18% of normal people had vascular murmurs. In the age group under 25, 44% had murmurs. These physiologic murmurs arise from the abdominal aorta at the epigastrium and from the interior vena cava. Aortic murmurs may be heard over the lower precordium and be confused with cardiac murmurs. The caval murmur is a high-pitched continuous hum heard best to the right of the umbilicus. Murmurs heard far laterally into the upper abdomen, in the flank, or in the lower quadrants are probably pathologic and represent vascular abnormalities. Radiation of cardiac valvular murmurs into the abdomen is most common with those arising from the aortic valve area.
Rivin AU. Abdominal Vascular Sounds. JAMA. 1972;221(7):688-690. doi:10.1001/jama.1972.03200200036008