An observational study in Bowel Sounds, Colorectal Cancer and Intestinal Obstruction, sponsored by Zhongnan Hospital. Recruiting at 1 site in China. Open to participants aged 18 Years to 90 Years. Per ClinicalTrials.gov, last updated 2026-07-15.
Sponsored by Zhongnan Hospital · Observational
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
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.
6,541 studies on the registry are indexed under Colorectal Neoplasms; 1,667 are open to participants now.
This study's planned enrollment of 172 is below the median of 250 across 1,440 observational studies indexed under Colorectal Neoplasms.
Browse Colorectal Neoplasms studies →Zhongnan Hospital is the lead sponsor of 106 studies on the registry; 49 are open to participants now.
Counted across the registry records on this site, refreshed daily.
This study enrolls patients scheduled to undergo curative surgery for colorectal cancer.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
No intestinal obstruction occurred during the perioperative period.
Procedure: colorectal surgery
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.
Occurrence of postoperative ileus ( POI) after surgery.
Time frame: From surgery through postoperative day 30
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.
Time frame: 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.
Time frame: 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.
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: From surgery through postoperative day 30
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Ran from Feb 2026 to primary completion in May 2026, 3 months.
Of 528 non-industry observational studies under Colorectal Neoplasms, half reached primary completion within 56 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 132. This study's 3 months is below that.
Counting every sponsor, half of 645 studies reached it within 51 months; a quarter within 27 and three quarters within 104.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.