Small and Large Bowel

Introduction Choosing drug therapy for irritable bowel syndrome (IBS) requires balancing symptom benefit against treatment-related adverse effects. While clinicians often use the number needed to treat (NNT) to compare efficacy, the number needed to harm (NNH) offers an equally important perspective by estimating how many patients need to be treated before one stops therapy because of an adverse event. This systematic review and meta-analysis evaluated the safety of commonly used IBS medications by focusing on discontinuation due to adverse events, a pragmatic marker of tolerability. Summary This meta-analysis included 54 placebo-controlled clinical trials involving 33,538 patients and assessed IBS-C, IBS-D, and global symptom therapies. The primary outcome was NNH, derived from treatment discontinuation due to adverse events. Among IBS-C therapies, the NNH was 35 for linaclotide, 53 for lubiprostone, 59 for plecanatide, 58 for tegaserod, and 16 for tenapanor. For IBS-D therapies, the NNH was 14 for alosetron and 32 for eluxadoline, while rifaximin and ramosetron had negative, nonsignificant NNH values, meaning placebo groups had numerically higher discontinuation rates than active treatment groups. For global IBS symptom therapy, tricyclic antidepressants had an NNH of 24. Overall, tenapanor, alosetron, and tricyclics had the greatest risk of treatment discontinuation due to adverse events, whereas rifaximin appeared to be the safest pharmacotherapy studied. The most common adverse effects reflected mechanism of action: diarrhea and nausea for IBS-C drugs, constipation for IBS-D drugs, and anticholinergic or sedative effects for tricyclics. Importantly, many adverse events were transient and nonserious. This study emphasizes that IBS treatment decisions should not rely on efficacy alone. Safety, tolerability, and patient preference should be central when selecting among multiple reasonable drug options.

The role of habitual diet in the global epidemiology of irritable bowel syndrome (IBS) remains incompletely understood. In this large international analysis from the Rome Foundation Global Epidemiology Study, investigators evaluated whether regional dietary patterns are associated with variations in IBS prevalence and symptom severity. A total of 54,127 participants from 26 countries completed questionnaires assessing Rome IV IBS criteria and frequency of intake of 10 food groups. Using latent class analysis, researchers identified four distinct dietary pattern clusters. These clusters demonstrated significant differences in both IBS prevalence and symptom severity. Clusters A (5.6%) and B (4.5%) had the highest IBS prevalence and symptom severity, and were largely represented by countries such as Egypt, Brazil, Colombia, Argentina, Germany, Poland, and the United States. In contrast, clusters C (3.4%) and D (2.6%), predominantly from Europe and Asian countries, showed lower IBS prevalence and milder symptoms. These findings suggest that regional dietary habits may contribute to global variations in IBS burden. Understanding population-specific dietary patterns may help design culturally appropriate dietary interventions for IBS management worldwide.

Introduction Upper small intestinal bacterial overgrowth (USIBO) is characterised by excessive bacterial colonisation in the duodenum or proximal jejunum, often leading to symptoms such as bloating, abdominal distension, and dyspepsia. Diagnosing USIBO remains challenging. Current methods include breath tests (glucose or lactulose hydrogen testing) and duodenal fluid aspiration, but both have important limitations. Breath tests have variable sensitivity and specificity, while aspirate cultures can be difficult to obtain and are prone to contamination and dilution, resulting in false-positive rates of up to 20%. These challenges have prompted exploration of alternative diagnostic techniques. Summary This study revisits the duodenal mucus brushing technique, an older but largely overlooked method for detecting bacterial overgrowth. During endoscopy, a cytology brush is used to collect mucus directly from the duodenal or proximal jejunal mucosa, targeting bacteria adherent to the mucosal surface rather than bacteria suspended in luminal fluid. In a cohort of 92 patients with suspected USIBO, bacterial growth was detected in 24% of cases using this technique. Streptococcus species were the most commonly identified organisms, followed by coliform bacteria. Importantly, contamination testing demonstrated a false-positive rate of only 8%, significantly lower than that reported with traditional duodenal aspiration. The authors propose that bacteria involved in USIBO preferentially adhere to the mucosal mucus layer, making mucus sampling a more accurate diagnostic source. The brushing technique is simple, reproducible, and can be performed during routine endoscopy, potentially improving the detection of small intestinal bacterial overgrowth in patients lacking duodenal fluid samples.

Introduction Chronic constipation is frequently evaluated using physiologic testing such as fluoroscopic defecography and high-resolution anorectal manometry to identify pelvic floor dysfunction and evacuation disorders. A recent study combined these techniques to define a synchronous “proctomanometric” signature of constipation. However, concerns have been raised about the methodological assumptions used to classify evacuation patterns. Accurate definitions and patient phenotyping are crucial because diagnostic thresholds and analytic models can strongly influence the interpretation of anorectal physiology and the clinical diagnosis of pelvic floor dyssynergia. Summary The correspondence highlights three methodological issues. First, the study defined “successful evacuation” as expelling ≥25% of rectal barium within three attempts lasting ≤17 seconds, a threshold that may be overly restrictive and physiologically unrealistic. Prior studies demonstrate that even healthy individuals may take >30 seconds to evacuate similar volumes, suggesting that strict time limits could generate false-positive diagnoses of impaired evacuation. Second, the study combined functional constipation (FC) and constipation-predominant IBS (IBS-C) using older Rome III criteria, despite Rome IV guidelines recognizing important pathophysiologic differences between these conditions. Pooling them may confound interpretation of anorectal pressure patterns. Third, the study applied machine-learning models with many predictors but limited sample size, raising concerns about overfitting and lack of reproducibility. The author proposes more physiologic evacuation metrics, Rome IV–based patient stratification, and more robust statistical validation to improve translation of these findings into clinical practice.

Introduction Colonoscopy has become the dominant colorectal cancer (CRC) screening test in the United States, credited with major reductions in CRC incidence and mortality through detection and polypectomy. Yet CRC screening uptake targets remain unmet, alternative tests (especially FIT) have strong evidence, and health systems are increasingly shifting from opportunistic to programmatic screening—raising an uncomfortable but necessary question: should colonoscopy still be promoted as “the best” screening choice? Summary This commentary argues that while colonoscopy is the most comprehensive colorectal examination and the “final common pathway” for all screening strategies, it cannot be automatically crowned the best population-wide screening test. The authors highlight that real-world effectiveness is not only about test efficacy, but also about participation, feasibility, adherence over time, and colonoscopy quality (which is operator dependent). In many countries, organised screening programs favour FIT because it is inexpensive, noninvasive, scalable, and can achieve high participation, with colonoscopy reserved for positive tests. The authors emphasise that programmatic stool-based screening—when repeated and paired with reliable follow-up colonoscopy—can deliver prevention benefits comparable to colonoscopy-based strategies. They point to recent randomised evidence, including COLONPREV, showing that invitations to FIT can achieve CRC incidence and mortality outcomes comparable to invitations to colonoscopy, while requiring fewer colonoscopies due to higher participation and triage. The piece also addresses the financial realities in US gastroenterology and the potential conflict of interest when colonoscopy is preferentially promoted. The conclusion is clear: gastroenterologists should champion CRC screening broadly, simplify choices where needed (often to colonoscopy vs stool-based testing), and align messaging with population-level effectiveness rather than defending colonoscopy as universally “best.”