Slide 1: Gut Check: Bowel Auscultation

Slide 2: Borborygmi (AKA bowel sounds): what trainees are taught.
– Auscultation (in all four quadrants!) before palpation
– High-pitched? Think SBO
– Hyperactive? Think gastroenteritis, IBD, laxative use, GI bleeding
– Absent? Think bowel obstruction, ileus, or ischemia

Slide 3:
Multiple studies report low sensitivities of auscultated bowel sounds.
– In one study, the presence of bowel sounds in normal, SBO, and POI (post-operative ileus) diagnoses held sensitivities of 32%, 22%, and 22%, respectively.
– PPVs are similarly low.

Slide 4:
The evidence – findings ≠ underlying physiology
Location, location? Bowel findings in one quadrant may not localize to that quadrant, as sounds frequently travel along the entire abdominal wall
Length of your listen: Cycles of borborygmi can last as long as 50 minutes, and a healthy patient can have up to 4 minutes of absent bowel sounds – thus, even severeal minutes of auscultation may not tell you much.

Slide 5:
What the evidence says: you and your colleague will likely disagree
Because bowel sounds are highly variable – changing on the order of seconds to minutes – they can shift from one auscultator to the next.
As such, it is unsurprising that studies consistently demonstrate low levels of inter-observer agreement among those listening for bowel sounds.

Slide 6:
SBO: when to consider reaching for your stethoscope
Patients with bowel obstruction frequently have abnormal bowel sounds – 40% have hyperactive, and 25% have diminished/absent sounds.
As such, the finding of normal bowel sounds can decrease the probability of bowel obstruction (LR = 0.4)

References

  • Breum BM et al. Accuracy of abdominal auscultation for bowel obstruction. World J Gastroenterol. 2015 Sep 14; 21(34): 10018–10024. PMID 26379407.
  • McGee S. Evidence-Based Physical Diagnosis. 4th Ed. Elsevier 2017: 459-460. ISBN 9780323392761.
  • Felder S et al. Usefulness of bowel sound auscultation: a prospective evaluation. J Surg Educ. 2014 Sep-Oct;71(5):768-73. PMID 24776861 .
  • Bree SHW et al. Auscultation for bowel sounds in patients with ileus: an outdated practice in the ICU? Netherlands Journal of Critical Care. 2018 26(4): 142-146. Link.
  • Baid H. A critical review of auscultating bowel sounds. Br J Nurs. 2009 Oct 8-21;18(18):1125-9.PMID 19966732.