Auscultation is the least important of the methods of examining the abdomen. It can furnish, however, in certain cases, information that may be confirmatory, suggestive or definite. The sounds that can be heard are of greater variety than those audible in the thorax, but are, as a rule, more vague and unsatisfactory. The sounds may be either intrinsic, produced in the abdominal cavity, or extrinsic, heard over the abdominal cavity but produced in some other part of the body, always the thorax. The auscultation can be divided into (1) direct, produced with the ear alone; (2) indirect, with some form of stethoscope, and (3) modified, in which some additional procedure, such as percussion, stroking, the bubbling of air through a tube, or the vibration of a tuning fork, is used.
It is rather difficult to classify satisfactorily the sounds heard in the abdomen. Perhaps as good a classification as any
SAILER J. AUSCULTATION IN THE PHYSICAL EXAMINATION OF THE ABDOMEN. JAMA. 1923;81(9):728-730. doi:10.1001/jama.1923.02650090026007