Inconsistent Diagnostic Criteria for IBS-C and Functional Constipation Identified in Global Guidelines
A scoping review published in BMC Gastroenterology revealed significant inconsistencies and regional variations in clinical practice guidelines (CPGs) for diagnosing constipation-predominant irritable bowel syndrome (IBS-C) and functional constipation (FC), two prevalent gastrointestinal disorders. The study highlights divergent diagnostic criteria across global guidelines, underscoring challenges in clinical decision-making.
Intestinal motility disorders such as IBS-C and FC are common in clinical practice but often overlap in symptom presentation. This review assessed diagnostic recommendations from 27 CPGs published between 2012 and 2024, drawing from major gastroenterology organizations and national guideline repositories.
Study Findings
The scoping review identified 14 guidelines for IBS-C, 9 for FC, and 4 covering both conditions. The Rome IV criteria were the predominant diagnostic framework (59.3%), followed by Rome III (22.2%). However, criterion usage varied markedly. For IBS-C, abdominal pain was a core criterion in 71.4% of CPGs, whereas spontaneous bowel movement frequency was central to FC diagnosis in 88.9% of FC guidelines but absent in IBS-C recommendations.
Only 40.7% of guidelines acknowledged symptom overlap between IBS-C and FC. A lone guideline incorporated abdominal pain intensity on a Likert scale (>4/9) to distinguish painful constipation subtypes. Moreover, geographic differences emerged: Asian guidelines more frequently included Bristol Stool Form Scale type 3 and bloating as diagnostic indicators.
Colonoscopy was recommended by 81.5% of CPGs based on age or alarm features. Variability also extended to laboratory, imaging, and functional testing recommendations, reflecting inconsistency in the extent of objective assessment versus symptom-based diagnosis.
Clinical Implications
These findings have practical consequences for clinicians managing adult patients with chronic constipation symptoms. The inconsistency in symptom emphasis—pain versus bowel movement frequency—can lead to misclassification of patients and potentially inappropriate treatment strategies. Accurate differentiation between IBS-C and FC is crucial, as management priorities differ: pain-focused therapies may benefit IBS-C, while laxative-based or motility-enhancing regimens may be prioritized for FC.
The observed regional guideline differences further complicate diagnostic uniformity, highlighting the need for clinicians to integrate guideline recommendations with local practice patterns and patient characteristics. Until objective biomarkers or validated diagnostic tools are established, clinicians should apply a comprehensive assessment incorporating both symptom profiles and selective testing to enhance diagnostic precision.
Furthermore, the overlap in presentations emphasizes the importance of engaging patients in detailed symptom reporting and considering individual symptom severity—not just presence or frequency—when making diagnostic decisions and planning treatment.
Reference: Luo J, To WLW, Xu Q, et al. Clinical practice guidelines for the diagnosis of constipation-predominant irritable bowel syndrome and functional constipation in adults: a scoping review. BMC Gastroenterology. 2025;25:234. doi:10.1186/s12876-025-03774-6.
