← Issue №8/ week of Aug 23, 2026/Motility

Magnetic Resonance Defecography Criteria for the Diagnosis of Dyssynergic Defecation.

From GI Signals issue №8: what this paper found, what it changes, and where it sits against the current standard of care, reviewed by Simon Mathews, MD.

Motility retrospective · n=109 · Aug 19, 2026 · J Neurogastro Motil · IF 3.4

Magnetic Resonance Defecography Criteria for the Diagnosis of Dyssynergic Defecation.

Diagnosticchronic constipationanorectal manometrybiomarker
Clinical takeawayIn chronic constipation patients suspected of dyssynergic defecation who cannot or decline HR-ARM, MRD may provide a non-invasive diagnostic alternative with moderate-to-good diagnostic odds ratios (8.25-14.25). Requires prospective external validation and clarification of specific diagnostic thresholds and their directional criteria before adoption as primary diagnostic criteria.
What it foundSpecific quantitative MRD parameters, M-line measurement, anorectal angle (ARA), and anal canal width (ACW), with emphasis on puborectalis muscle prominence or abnormal evacuation assessment, demonstrated discriminatory ability for dyssynergic defecation. Numeric cutoff thresholds (M-line 2.0 cm, ARA 114°, ACW 10 mm) achieved specificities of 82.1-92.3%, positive likelihood ratios of 3.66-7.06, and diagnostic odds ratios of 8.25-14.25; ARA and ACW at defecation were identified as independent predictors. Direction of cutoff relationship to dyssynergic diagnosis specified in source.
ContextDyssynergic defecation is currently diagnosed via high-resolution anorectal manometry combined with functional testing (balloon expulsion). MR defecography is non-invasive dynamic imaging of pelvic floor mechanics during defecation. Prior evidence for MRD diagnostic criteria in dyssynergic defecation is limited. This retrospective study establishes specific MRD measurement thresholds that discriminate dyssynergic defecation from normal, potentially providing an imaging-based diagnostic alternative for patients who cannot or refuse manometry.
Emergingsuggested applicable standard· American Gastroenterological Association & American College of Gastroenterology, "American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation" (Chang L, Chey WD, Imdad A, et al.), 2023

Decision at stakehow to diagnose dyssynergic defecation in patients presenting with constipation, to determine appropriate management pathway

No single passage of this standard matched the paper closely enough to quote, so none is shown. The standard is cited above.

Our full summary of this standard

In adults with chronic idiopathic constipation, the AGA-ACG panel makes 10 GRADE-based pharmacological recommendations, and the strength tier is part of the recommendation. Unqualified as to prior therapy: STRONG recommendation (moderate certainty) for polyethylene glycol; STRONG recommendation (moderate certainty) for bisacodyl or sodium picosulfate, but explicitly qualified as short-term or rescue therapy; CONDITIONAL suggestion for fiber supplementation (low certainty), magnesium oxide (very low certainty), and senna (low certainty). Reserved for patients who do not respond to, fail, or are intolerant of over-the-counter agents: STRONG recommendation (moderate certainty) for linaclotide, plecanatide, and prucalopride; CONDITIONAL suggestion for lubiprostone (low certainty) and lactulose (very low certainty). The guideline states no specific doses, no mandatory ordering algorithm, and no fixed trial duration; it notes only that nonpharmacological therapies 'often represent the initial steps in management' and directs clinicians to shared decision making incorporating patient preference, cost, and availability. The guideline explicitly does not cover anorectal evacuation disorders, referring those to the ACG 2021 benign anorectal guideline.

American Gastroenterological Association & American College of Gastroenterology, "American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation" (Chang L, Chey WD, Imdad A, et al.), 2023 · reviewed 2026-07-19 ↗
Keeratichananont S … Netinatsunton N · Journal of Neurogastroenterology and Motility · IF 3.4 · PubMed ↗Permalink
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