The Value of Bowel Sounds in Evaluating Postoperative Intestinal Function Recovery in Colorectal Cancer Patients (BRIEF)

The Value of Bowel Sounds in Evaluating Postoperative Intestinal Function Recovery in Colorectal Cancer Patients: A Prospective Cohort Study

This study enrolls patients scheduled to undergo curative surgery for colorectal cancer. Bowel sounds will be assessed preoperatively and postoperatively. By comparing intraoperative variables, the incidence of perioperative complications, reoperation rates, and postoperative outcomes-including time to first flatus, resumption of oral intake, and occurrence of intestinal obstruction-this study aims to investigate the association between perioperative bowel sounds and postoperative recovery, and provide evidence-based support for the clinical application of bowel sound monitoring.

Supplementary Definitions

Study Overview

• Status: Recruiting
• Conditions: Colorectal Cancer; Colorectal Surgery; Intestinal Obstruction; Postoperative Ileus; Bowel Sounds
• Intervention / Treatment: Procedure: colorectal surgery

Detailed Description

Colorectal cancer (CRC) is the third most common malignancy worldwide and the second leading cause of cancer-related mortality. In recent years, both the incidence and mortality of colorectal cancer in China have shown a significant upward trend. With population aging and lifestyle changes, the disease is increasingly affecting younger individuals, with the proportion of patients under 40 years of age steadily rising. Treatment strategies vary according to disease stage; however, for most cases amenable to primary resection, surgical intervention remains the cornerstone of therapy.

With the widespread implementation of Enhanced Recovery After Surgery (ERAS) protocols, postoperative rehabilitation has been substantially improved through optimization of preoperative, intraoperative, and postoperative management strategies, such as shortened preoperative fasting, the use of laparoscopic techniques, and early postoperative oral intake, thereby facilitating accelerated recovery and earlier discharge. Following curative surgery for colorectal cancer, patients commonly experience reduced or transiently absent intestinal motility due to surgical manipulation and the effects of anesthesia, with gradual return to normal function over several days. Early postoperative feeding has been shown to promote gastrointestinal functional recovery.

However, a subset of patients may exhibit delayed recovery of bowel function, characterized by diminished bowel sound activity, prolonged time to first flatus, and often accompanied by abdominal distension. Postoperative ileus (POI) is one of the most common causes of delayed postoperative gastrointestinal recovery and typically presents as transient suppression of gastrointestinal motility. When the duration exceeds the expected physiological range, potential pathological conditions, such as early postoperative small bowel obstruction (EPSBO), should be considered. In such circumstances, oral intake may exacerbate the ileus and even precipitate intestinal obstruction. Therefore, timely differentiation and accurate diagnosis of the patient's postoperative gastrointestinal status are of critical importance.

Abdominal auscultation, as a noninvasive diagnostic technique, has a history spanning several centuries. In 1905, Cannon was the first to report systematic investigations of abdominal auscultation, proposing that regular bowel sounds are generated by intestinal peristaltic activity. Subsequent studies have demonstrated that bowel sounds vary by anatomical location: sounds originating from the small intestine are typically high-pitched, high-amplitude, and frequent, whereas colonic sounds are lower in frequency, weaker in amplitude, and less frequent. Postoperatively, the recovery of gastrointestinal motility differs among intestinal segments, with the small intestine recovering first, followed by the stomach and the colon.

Abdominal auscultation has been widely used as an adjunctive tool in the evaluation of conditions such as intestinal obstruction and ileus owing to its immediacy and convenience and is commonly applied in patients with delayed postoperative gastrointestinal recovery. However, the reliability of auscultation-based assessment remains controversial because of the inherent subjectivity in clinicians' descriptions of bowel sounds. A prospective study by Felder et al. demonstrated a low sensitivity of 22%-32% for manual auscultation in distinguishing healthy from diseased individuals, along with low positive predictive values of 23%-44%. Similarly, Thomas et al. conducted a prospective study examining the relationship between auscultated bowel sounds and postoperative oral tolerance and flatus, finding no significant correlation between bowel sounds and postoperative abdominal distension, flatus, defecation, or tolerance of oral intake.

Therefore, digital bowel sound monitoring devices, which objectively detect and analyze bowel sounds, have emerged as important adjunctive tools for postoperative bowel sound assessment. These systems enable precise quantification of acoustic features such as frequency, amplitude, and energy. Currently, both domestic and international researchers have begun to explore the use of bowel sound monitoring systems in the diagnosis and management of gastrointestinal disorders. Preliminary small-sample studies suggest that such systems hold substantial clinical potential in the precision management of intestinal obstruction, the diagnosis of functional gastrointestinal disorders, and the prediction of acute gastrointestinal injury in critically ill patients.

Nevertheless, progress in bowel sound monitoring technology has been relatively slow, primarily because of several challenges: (1) the weak and highly stochastic nature of bowel sound signals; (2) substantial interference from environmental and internal physiological noise; and (3) dynamic fluctuations in bowel sounds related to individual physiological states, with marked interindividual variability. To address these challenges, our center has independently developed a highly intelligent digital bowel sound monitoring system based on a distributed, multichannel, real-time acquisition framework. This system enables simultaneous collection of bowel sound signals from different abdominal regions while concurrently recording **cardiac sounds** and ambient noise as reference signals for noise suppression, followed by centralized classification and recognition of bowel sounds. Through this approach, bowel sound signals can be accurately extracted in complex acoustic environments, significantly improving the accuracy of feature detection, parameter computation, and classification algorithms while also assisting clinicians with synchronized auscultation.

At present, our center has conducted multiple iterations of the bowel sound monitoring device, completing optimized denoising and detection algorithms that enable accurate extraction of bowel sound signals in complex environments. Furthermore, we have implemented a bowel sound recognition algorithm that integrates an attention-based Broadcasting Residual Neural Network (Broadcasting ResNet) with a Dual-Path Recurrent Neural Network (Dual-Path RNN). This algorithm is capable of extracting time-frequency features of bowel sounds, thereby supporting the auxiliary diagnosis of various intestinal disorders.

In summary, there is an urgent need for a high-quality, prospective clinical trial to investigate the predictive value of digital bowel sound monitoring for postoperative gastrointestinal functional recovery. Such a study would facilitate the clinical translation of this technology and assist clinicians in the diagnosis and early intervention of postoperative intestinal dysfunction.

• Study Type: Observational
• Enrollment (Estimated): 172

Contacts and Locations

• Study Contact: Name: siyuan yin, master; Phone Number: +86 18771708286; Email: 2023283030136@whu.edu.cn

Study Locations

• China
  • Hubei
    • Wuhan, Hubei, China
      • Recruiting
      • Zhongnan Hospital of Wuhan University
      • Contact: siyuan Yin, Master; Phone Number: +8618771708286; Email: 2023283030136@whu.edu.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This study enrolls patients scheduled to undergo curative surgery for colorectal cancer.

Description

Inclusion Criteria:

• Aged 18-80 years.
• Histopathologically confirmed colorectal adenocarcinoma according to the WHO 2022 classification.
• No restriction on prior neoadjuvant or other antitumor therapies, including chemotherapy, radiotherapy, targeted therapy, or immunotherapy.
• Able to understand the study requirements and voluntarily provide written informed consent (patient and/or legally authorized representative).
• Able to communicate effectively with the investigators and willing to comply with all study procedures, including postoperative management and follow-up.

Exclusion Criteria:

• Significant organ dysfunction indicating inability to tolerate surgery or an unacceptably high perioperative risk, including:
• Severe cardiac dysfunction (NYHA Class III or IV).
• Severe hepatic dysfunction (MELD score >12).
• Severe renal dysfunction (eGFR <30 mL/min/1.73 m² [CKD stage 4-5] or end-stage renal disease requiring dialysis).
• Severe pulmonary dysfunction (resting PaO₂ <60 mmHg on room air or respiratory failure requiring long-term oxygen therapy or mechanical ventilation).
• Participation in another clinical study within 4 weeks before enrollment or concurrent participation in another interventional clinical study.
• Emergency surgery required because of intestinal obstruction, perforation, or other acute abdominal conditions.
• Severe psychiatric disorders that would interfere with compliance with perioperative management or follow-up.
• Pregnant or breastfeeding women.
• Any other clinical or laboratory abnormality that, in the opinion of the investigator, would make the participant unsuitable for the study.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
normal group; No intestinal obstruction occurred during the perioperative period.	Procedure: colorectal surgery; Based on the preoperative multidisciplinary team (MDT) discussion, the appropriate surgical procedure was selected, including right hemicolectomy, left hemicolectomy, or radical resection for rectal cancer, as clinically indicated.
POI group; Intestinal obstruction occurred during the perioperative period.	Procedure: colorectal surgery; Based on the preoperative multidisciplinary team (MDT) discussion, the appropriate surgical procedure was selected, including right hemicolectomy, left hemicolectomy, or radical resection for rectal cancer, as clinically indicated.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Occurrence of postoperative ileus ( POI) after surgery.	From surgery through postoperative day 30

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Complications within 30 Days	Incidence of complications such as anastomotic leak/dehiscence, anastomotic bleeding, ischemic bowel necrosis, intra-abdominal infection, intra-abdominal hemorrhage, early postoperative intestinal obstruction, postoperative ileus, pulmonary infection, and other complications, as well as reoperations resulting from these events. The severity of complications will be graded using the Classification of Surgical Complications.	From surgery through postoperative day 30
Length of postoperative hospital stay	Length of postoperative hospital stay, defined as the number of days from the date of surgery to the date of hospital discharge. A longer hospital stay indicates delayed postoperative recovery or the occurrence of postoperative complications.	From surgery through postoperative day 30
Time to first flatus	Time to first flatus, defined as the time (in hours) from the completion of surgery to the patient's first reported passage of flatus.	From surgery through postoperative day 30
Time to first defecation	Time to first defecation, defined as the time (in hours) from the completion of surgery to the patient's first bowel movement	From surgery through postoperative day 30
Total hospitalization cost (before reimbursement)	Total hospitalization cost before reimbursement, defined as the total medical expenses incurred during the index hospitalization prior to any insurance reimbursement or financial assistance, as recorded in the hospital billing system.	From surgery through postoperative day 30
Bowel Sound Characteristics	Five-minute bowel sound recordings obtained at 2 h, 6 h, 12 h, 24 h, 36 h, 48 h, 60 h, 72 h, 84 h, and 96 h postoperatively, with corresponding acoustic feature analyses.	From surgery through postoperative day 30

Collaborators and Investigators

• Sponsor: Zhongnan Hospital
• Collaborators: Wuhan University
• Investigators: Study Chair: Congqing Jiang, professor, Shanghai Zhongshan Hospital

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2026
• Primary Completion (Actual): May 15, 2026
• Study Completion (Estimated): July 28, 2026

Study Registration Dates

• First Submitted: June 3, 2026
• First Submitted That Met QC Criteria: July 9, 2026
• First Posted (Actual): July 15, 2026

Study Record Updates

• Last Update Posted (Actual): July 15, 2026
• Last Update Submitted That Met QC Criteria: July 9, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Colorectal Cancer; Postoperative Ileus; Colorectal Surgery; bowel sounds; Intestinal Obstruction
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Intestinal Diseases; Gastrointestinal Neoplasms; Digestive System Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Intestinal Neoplasms; Rectal Diseases; Colonic Diseases; Colorectal Neoplasms; Intestinal Obstruction
• Other Study ID Numbers: ZNH-2025-BA-02

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No