Auscultation of Bowel Sounds and Ultrasound of Peristalsis Are Neither Compartmentalized Nor Correlated

Objective  Auscultation of bowel sounds has been taught as a component of the physical examination since the beginning of the 20th century. However, there has been little research or consensus on the significance of listening in different quadrants. Some textbooks indicate that bowel sounds are the result of peristalsis in that region, while others state that bowel sounds can be generalized over the entire abdominal wall. With ultrasonography, peristalsis can be visualized in a dynamic and non-invasive manner. The purpose of this study was to determine the relationship between auscultation of bowel sounds and visualization of peristalsis with ultrasound, to understand whether or not bowel sounds and peristalsis are compartmentalized. Methods  Study participants quietly lay supine, while one investigator positioned an ultrasound probe on the abdomen visualizing the small intestine, and a second investigator placed an EKO Digital Stethoscope (Eko Devices, Inc., Oakland, CA) directly adjacent to the probe auscultate for bowel sounds. During a two-minute interval, a third investigator noted every time a bowel sound was heard (A+), peristalsis was seen (U+), or a combined event (C+) occurred, recording the total number of events. Measurements were recorded from four quadrants (right upper quadrant {RUQ}, left upper quadrant {LUQ}, right lower quadrant {RLQ}, left lower quadrant {LLQ}) and the periumbilical region (PUR). Fisher Exact test was used to determine whether there were significant differences between the number of bowel sounds heard but not seen (A+) and those seen but not heard (U+) with sounds that were both seen and heard (C+). Significance was determined with p < 0.05. Results  A total of 16 participants were included, with a combined 973 discrete bowel events, both auscultated and visualized. No quadrant showed a significant correlation between an isolated sound (A+) or peristalsis (U+) and a combined event (C+), indicating there were many events where an auscultated sound failed to correlate with observed peristalsis, and vice versa. The average p-value was 0.544, with a range of 0.052-1.00. Conclusion  This study showed that there is no significant correlation between auscultated bowel sounds and peristalsis within a given region. This study calls into question whether auscultation of all four quadrants provides more meaningful information than auscultation of one central point of the abdomen.