Distinguishing Functional Constipation From IBS-C and Embracing a Positive Diagnosis

Learn how Rome V criteria, predominant symptom drivers, and a positive diagnostic framework help clinicians distinguish functional constipation from pediatric IBS-C and move away from a diagnosis-of-exclusion mindset.

Pediatric functional constipation and irritable bowel syndrome with constipation (IBS-C) frequently present with overlapping symptoms, posing a diagnostic challenge for clinicians. In this discussion, pediatric gastroenterologist Julie Khlevner, MD, emphasizes that both conditions fall under the umbrella of disorders of gut–brain interaction and are best approached using symptom-based tools such as the Rome V criteria. She notes that Rome V provides a practical framework for parsing patterns of stooling, pain, and associated features, allowing clinicians to reach a confident, positive diagnosis rather than defaulting to an exclusionary label.

Khlevner explains that functional constipation is typically characterized by infrequent and/or painful defecation, fecal incontinence, passage of large-diameter stools, and fecal impaction. In contrast, IBS is driven primarily by abdominal pain that is often temporally related to defecation and associated with changes in stool form and frequency. Diagnostic uncertainty arises when children with significant constipation also report abdominal pain, bloating, and discomfort; fecal retention itself can generate visceral hypersensitivity that mimics IBS. She advises that IBS should be diagnosed when pain clearly remains the predominant, persistent symptom, even in the presence of constipation-related signs.

Historically, families often experienced IBS as a diagnosis of exclusion, conferred only after extensive testing failed to identify an “organic” cause, a process that could heighten anxiety and undermine confidence in the diagnosis. Khlevner describes how the Rome framework and a growing understanding of disorders of gut–brain interaction have enabled her to present IBS and functional constipation as legitimate biopsychosocial conditions diagnosed clinically when characteristic symptom patterns are present and alarm features are absent. She stresses that a positive diagnosis does not negate the need for careful history, physical examination, growth assessment, and selective testing, but it does shift the emphasis from “ruling everything out” to recognizing a well-described condition with known mechanisms and evidence-based management strategies.