Brief Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Sep 7, 2012; 18(33): 4585-4592
Published online Sep 7, 2012. doi: 10.3748/wjg.v18.i33.4585
Spectral analysis of bowel sounds in intestinal obstruction using an electronic stethoscope
Siok Siong Ching, Yih Kai Tan
Siok Siong Ching, Yih Kai Tan, Department of Surgery, Changi General Hospital, Singapore 529889, Singapore
Author contributions: Ching SS conceived and designed the study, provided supporting material, acquired the data, performed the statistical analysis, interpreted the data and wrote the manuscript; Tan YK supervised the study and critically revised the manuscript.
Correspondence to: Siok Siong Ching, MRCS, MD, Department of Surgery, Changi General Hospital, 2 Simei Street 3, Singapore 529889, Singapore. ching_ss@hotmail.com
Telephone: +65-97729648    Fax: +65-62601709
Received: October 16, 2011
Revised: February 10, 2012
Accepted: March 10, 2012
Published online: September 7, 2012
Abstract

AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction.

METHODS: Subjects were patients who presented with a diagnosis of possible intestinal obstruction based on symptoms, signs, and radiological findings. A 3M™ Littmann® Model 4100 electronic stethoscope was used in this study. With the patients lying supine, six 8-second recordings of bowel sounds were taken from each patient from the lower abdomen. The recordings were analysed for sound duration, sound-to-sound interval, dominant frequency, and peak frequency. Clinical and radiological data were reviewed and the patients were classified as having either acute, subacute, or no bowel obstruction. Comparison of bowel sound characteristics was made between these subgroups of patients. In the presence of an obstruction, the site of obstruction was identified and bowel calibre was also measured to correlate with bowel sounds.

RESULTS: A total of 71 patients were studied during the period July 2009 to January 2011. Forty patients had acute bowel obstruction (27 small bowel obstruction and 13 large bowel obstruction), 11 had subacute bowel obstruction (eight in the small bowel and three in large bowel) and 20 had no bowel obstruction (diagnoses of other conditions were made). Twenty-five patients received surgical intervention (35.2%) during the same admission for acute abdominal conditions. A total of 426 recordings were made and 420 recordings were used for analysis. There was no significant difference in sound-to-sound interval, dominant frequency, and peak frequency among patients with acute bowel obstruction, subacute bowel obstruction, and no bowel obstruction. In acute large bowel obstruction, the sound duration was significantly longer (median 0.81 s vs 0.55 s, P = 0.021) and the dominant frequency was significantly higher (median 440 Hz vs 288 Hz, P = 0.003) when compared to acute small bowel obstruction. No significant difference was seen between acute large bowel obstruction and large bowel pseudo-obstruction. For patients with small bowel obstruction, the sound-to-sound interval was significantly longer in those who subsequently underwent surgery compared with those treated non-operatively (median 1.29 s vs 0.63 s, P < 0.001). There was no correlation between bowel calibre and bowel sound characteristics in both acute small bowel obstruction and acute large bowel obstruction.

CONCLUSION: Auscultation of bowel sounds is non-specific for diagnosing bowel obstruction. Differences in sound characteristics between large bowel and small bowel obstruction may help determine the likely site of obstruction.

Keywords: Bowel sounds; Intestinal obstruction; Spectral analysis; Electronic stethoscope