Universally, trauma professionals are taught how to listen for bowel sounds during their training. And most healthcare professionals these days still listen for them during routine examinations. But remember, if you find yourself saying “that’s the way we always do it,” be careful!
Yes, we’ve been taught to perform this examination literally for centuries. But is it valuable? No one seems to ask that question anymore. A nurse from Brighton in the UK published a review about 25 years ago that most readers are not familiar with. She performed a 10-year review of the literature, searching on the keyword “bowel sounds.” It turns out there were very few hits. The search was widened to include another 20 years, and the terms “abdominal examination” and “abdominal physical assessment.” Based on these search difficulties, you can see how much we take this skill for granted and how little has been written about it.
All told, only five papers were identified. Typical exam parameters described included the normal frequency of bowel sounds, how long to listen if no sounds are heard, the locations to auscultate, and whether to palpate first and then listen, or listen then palpate.
Frequency of normal bowel sounds. Most papers agreed that normal bowel sounds are heard between every 5-15 seconds to every 5-35 seconds. Unfortunately, the frequency can vary, making it nearly impossible to distinguish hypoactive from hyperactive bowel sounds.
How long to listen. The literature varied from 2 minutes in the right lower quadrant only (?) to 7 minutes in all four quadrants. Some suggested that if no sounds were heard, the examiner should palpate the abdomen to stimulate peristalsis.
No palpation before auscultation. This was stated in all the papers. The fear was that it would increase the frequency of bowel sounds and confuse the examiner.
Bottom line: As in much of medicine, there is little literature to truly guide us here. There is substantial variability in reported results, and considerable clinician variability even in describing whether a patient’s bowel sounds were loud or soft, hypoactive or hyperactive. Most of what we take for granted with this exam tool is based on tradition, personal preference, and anecdotal teaching.
In trauma care, I don’t believe there is any value in spending time (which we don’t have much of during a trauma resuscitation anyway) listening for bowel sounds in a noisy room. We have all taken care of patients with a gunshot to the abdomen who have bowel sounds, and a minimally injured patients who have none. The best practice is to perform a good physical inspection and palpation of the abdomen, followed by appropriate x-rays or scans. Save your stethoscope for the chest exam.
Reference: A critical review of auscultating bowel sounds. Br J Nurs. 2009 Oct 8-21;18(18):1125-9. doi: 10.12968/bjon.2009.18.18.44555. PMID: 19966732.