Automated Bowel Sound Analysis: An Overview

Abstract

Despite technological progress, we lack a consensus on the method of conducting automated bowel sound (BS) analysis and, consequently, BS tools have not become available to doctors. We aimed to briefly review the literature on BS recording and analysis, with an emphasis on the broad range of analytical approaches. Scientific journals and conference materials were researched with a specific set of terms (Scopus, MEDLINE, IEEE) to find reports on BS. The research articles identified were analyzed in the context of main research directions at a number of centers globally. Automated BS analysis methods were already well developed by the early 2000s. Accuracy of 90% and higher had been achieved with various analytical approaches, including wavelet transformations, multi-layer perceptrons, independent component analysis and autoregressive-moving-average models. Clinical research on BS has exposed their important potential in the non-invasive diagnosis of irritable bowel syndrome, in surgery, and for the investigation of gastrointestinal motility. The most recent advances are linked to the application of artificial intelligence and the development of dedicated BS devices. BS research is technologically mature, but lacks uniform methodology, an international forum for discussion and an open platform for data exchange. A common ground is needed as a starting point. The next key development will be the release of freely available benchmark datasets with labels confirmed by human experts.

Keywords: automated analysis; bowel sound; intestine; motility; recording.

Figure 1

Spectrograms depicting bowel sounds recorded using a contact microphone in the right lower quadrant of the abdomen. (A) An individual short bowel sound is clearly discernible in the middle (~425 ms; indicated by the arrow at the top). The signal below 250 Hz is composed of venous hum and heart beats. (B) A series of over 50 bowel sounds (arrows) occurring in less than 1.5 s.