Defecation List

Abstract

The Defecation List (Dutch: Defecatielijst, also clinically designated as the defecation diary, bowel diary, or stool record) is an ecologically valid, prospective clinical assessment instrument and behavioral self-monitoring diary designed to capture real-time defecation patterns, bowel habits, fecal incontinence episodes, and associated evacuation difficulties in adult and geriatric populations. Developed within gastroenterology and pelvic floor physical therapy frameworks—synthesizing foundational work by Satish S. C. Rao (2004) and standardized for Dutch clinical practice by Esther Bols and colleagues under the auspices of the Royal Dutch Society for Physical Therapy (Koninklijk Nederlands Genootschap voor Fysiotherapie; KNGF, 2011)—the instrument addresses the severe recall bias inherent in retrospective self-reports of bowel frequency and consistency. The instrument comprises eight core observational parameters recorded per evacuation or leakage episode over an active observation period typically spanning 7 to 14 consecutive days. These parameters assess event timing, visceral sensory perception (urgency), morphologic stool consistency graded via the Bristol Stool Form Scale (BSFS Types 1–7), subjective evacuation volume (scanty, normal, copious), severity and nature of involuntary fecal loss (smear, liquid, formed), mechanical evacuation effort (straining), post-defecatory tenesmus (sensation of incomplete evacuation), and peridefecatory abdominal or anorectal pain. Psychometrically, the Defecation List operates as an event-level prospective clinical registry rather than a reflective latent psychometric sum scale. Its clinical utility is underpinned by exceptional content validity, robust criterion concordance with objective gastrointestinal transit time markers (radiopaque markers and scintigraphy), superior diagnostic accuracy over retrospective recall (which systematically underestimates incontinence and overestimates regularity), and strong intra-individual test-retest reliability across repeated monitoring weeks in stable functional anorectal disorders. By operationalizing diagnostic thresholds from the Rome IV criteria for functional constipation, dyssynergic defecation, and fecal incontinence, the Defecation List provides clinicians, pelvic floor physiotherapists, and clinical researchers with an indispensable evidentiary foundation for behavioral, biofeedback, pharmacological, and surgical interventions.

Keywords

Defecation List, Defecatielijst, bowel diary, Bristol Stool Form Scale, fecal incontinence, functional constipation, pelvic floor physical therapy, ecological momentary assessment, dyssynergic defecation, Rome IV criteria

Authors

The conceptual framework, prospective clinical validation, and standardization of the Defecation List stem from prominent international gastroenterological clinical research and Dutch pelvic health physical therapy consensus groups:

• Satish S. C. Rao, MD, PhD, FRCP (LON) — Professor of Medicine, Director of Neurogastroenterology/Motility, Medical College of Georgia, Augusta University, Augusta, Georgia, United States. Rao developed seminal methodologies for prospective stool diaries and diagnostic protocols for dyssynergic defecation, biofeedback therapy, and fecal incontinence assessment (Rao, 2004).
• Esther M. J. Bols, PhD, PT — Assistant Professor and Pelvic Health Physical Therapy Researcher, Department of Epidemiology, CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands. Bols led the clinical measurement instrument standardization for the Royal Dutch Society for Physical Therapy (KNGF) Clinical Practice Guideline for physical therapy in patients with stress and fecal incontinence (Bols et al., 2011, 2012).
• KNGF Guideline Development Group on Pelvic Floor Dysfunction — Koninklijk Nederlands Genootschap voor Fysiotherapie (Royal Dutch Society for Physical Therapy), Amersfoort, The Netherlands. The expert task force dedicated to the psychometric operationalization, implementation, and clinical profiling of outcome measurement tools (Meetinstrumenten) across Dutch primary and specialized healthcare echelons.

Purpose

The Defecation List serves as a rigorous, prospective diagnostic and outcome measurement instrument designed to capture an unadulterated, real-time chronicle of human defecatory behavior, physiological transit indicators, and functional anorectal abnormalities. Retrospective self-reports regarding bowel habits are notorious across internal medicine and behavioral healthcare for profound systemic error. Human recall of stool frequency, consistency, and involuntary leakage is significantly confounded by memory decay, availability heuristics, cognitive dissonance, emotional distress, and societal taboo surrounding gastrointestinal excretion. Studies consistently demonstrate that patients with functional gastrointestinal disorders (FGIDs)—including irritable bowel syndrome (IBS), functional constipation, and accidental bowel leakage—misestimate their true defecation and incontinence frequencies by up to 50% when asked to summarize their preceding weeks or months. The primary clinical and empirical purpose of the Defecation List is to circumvent this recall distortion through systematic, event-based prospective tracking.

In clinical practice, the Defecation List is deployed across gastroenterology, urogynecology, colorectal surgery, geriatrics, and specialized pelvic floor physical therapy clinics. It accomplishes multiple diagnostic and therapeutic goals:

• Establishing Baseline Phenotypes: It establishes a precise baseline of bowel habits prior to any therapeutic intervention, differentiating slow-transit constipation, normal-transit constipation, obstructive/dyssynergic defecation, and diarrhea-predominant patterns.
• Quantifying Incontinence Severity: It records the precise frequency, timing, and physical consistency of involuntary fecal loss (distinguishing minor passive soiling/smears from catastrophic liquid or formed stool incontinence), which is essential for staging fecal incontinence according to standardized severity indices.
• Correlating Somatosensory and Behavioral Dimensions: The diary illuminates the relationship between visceral sensation (e.g., sudden urgency or absence of normal rectal filling sensation) and maladaptive behaviors (e.g., excessive, prolonged Valsalva straining or deferred defecation).
• Monitoring Treatment Responsiveness: Administered longitudinally, it acts as a sensitive evaluative metric to quantify therapeutic efficacy across conservative behavioral modifications (dietary fiber titrations, fluid scheduling, biofeedback retraining, pelvic floor muscular down-training or strengthening), neuromodulation (sacral nerve stimulation), and surgical interventions.
• Fostering Patient Self-Management and Biofeedback: Completing the diary heightens patients’ somatic awareness regarding the interplay between daily routines, dietary triggers, emotional stressors, toilet posturing, and bowel function, serving as an active psychoeducational component of cognitive-behavioral and pelvic physical therapy interventions.

Psychological Construct

Although rooted in gastrointestinal physiology, the Defecation List operationalizes complex multi-system constructs spanning neurogastroenterology, health psychology, somatic awareness, and the bidirectional brain-gut-microbiome axis. Defecation is not an isolated mechanical reflex; in humans, it represents an intricate integration of autonomic enteric nervous system signaling, central sensory processing, visceral interoception, cortical inhibition, and learned voluntary motor behaviors. The eight parameters of the Defecation List map onto distinct dimensions of this psychophysiological construct:

1. Temporal Regularity and Circadian Motility (Time of Event)

Gastrointestinal colonic motor activity exhibits pronounced circadian rhythmicity, characterized by high-amplitude propagating contractions (HAPCs) upon waking and following postprandial gastrocolic reflexes. The recording of the precise event timestamp tracks whether an individual possesses intact circadian colonic signaling or dysregulated, unpredictable motor patterns frequently observed in chronic visceral anxiety, autonomic dystonia, and severe slow-transit pathology.

2. Visceral Sensation and Interoceptive Urgency (Aandrang ervaren)

Visceral perception reflects the afferent signaling from rectal mechanoreceptors traversing pelvic splanchnic nerves to the dorsal horn of the spinal cord, thalamus, and insular cortex. The dichotomous presence or absence of urgent rectal sensation captures both visceral hypersensitivity (extreme urgency triggering panic, agoraphobic fear of incontinence, and social withdrawal) and visceral hyposensitivity (blunted rectal compliance and failure to perceive impending defecation, leading to overflow fecal impaction in both neurological conditions and behavioral chronic stool withholding).

3. Stool Morphology as a Proxy for Intestinal Transit (Bristol Stool Form Scale)

The morphological appearance of the stool (categorized from Type 1, discrete hard lumps, to Type 7, watery liquid without solid pieces) serves as a validated surrogate metric for whole-gut and segmental colonic transit time. Slow transit facilitates excessive mucosal fluid reabsorption resulting in hard, scybalous feces (Types 1–2), whereas accelerated motor propulsion bypasses normal absorptive processes yielding loose or diarrheic consistency (Types 5–7). Evaluating stool consistency provides objective evidence regarding luminal physiology independent of subjective patient labeling of “diarrhea” or “constipation”.

4. Volumetric Perception (Hoeveelheid ontlasting)

Tracking whether evacuations are perceived as scanty, normal, or voluminous gauges rectal evacuator efficiency and correlates with functional storage capacity. Scanty, fragmented evacuations recurring multiple times daily often signify pelvic floor dyssynergia, rectocele pocketing, or internal rectal intussusception, where the rectal reservoir is unable to empty completely in a single unified physiological event.

5. Involuntary Fecal Loss and Incontinence Phenomenology (Ongewild verlies van ontlasting)

Fecal incontinence embodies profound psychological distress, societal stigma, shame, and diminished quality of life. Differentiating involuntary loss into minor fecal smearing/staining, uncontrolled liquid stool, or fully formed accidental bowel leakage operationalizes distinct physiological mechanisms: internal anal sphincter resting tone deficits, external anal sphincter muscle tears, pelvic floor neuropathy, or overwhelming rectal reservoir compliance collapse.

6. Obstructive Mechanical Effort and Behavioral Straining (Moeten persen)

Straining reflects excessive, unphysiological pelvic expulsion effort. Excessive Valsalva straining indicates functional outlet obstruction, frequently underpinned by pelvic floor dyssynergia (paradoxical puborectalis contraction or failure of the external sphincter to relax during attempted defecation). Psychologically, chronic straining is reinforced by health anxiety, obsessive-compulsive cleanliness tendencies, and somatic hypervigilance centered upon absolute colonic evacuation.

7. Visceral Tenesmus and Incomplete Evacuation (Gevoel van onvolledige lediging)

The post-defecation sensation of incomplete emptying represents a cardinal diagnostic criterion for dyssynergic defecation and irritable bowel syndrome. It reflects either persistent physical stool retention due to pelvic outlet mechanical barriers or an altered interoceptive rectal threshold wherein hyper-sensitized rectal mucosa interprets residual inflammatory or mucosal touch as an ongoing presence of mass, perpetuating chronic distress and prolonged toilet sitting.

8. Peridefecatory Visceral Pain and Abdominal Cramping (Pijn of krampen)

Peridefecatory nociceptive intensity reflects visceral pain amplification and central sensitization within the brain-gut axis. Visceral hyperalgesia is intimately tied to psychiatric comorbidities such as generalized anxiety disorder, post-traumatic stress disorder, and clinical depression. Quantifying pain ranging from none to severe permits clinicians to dissociate primary pelvic motor dysfunction from generalized functional visceral pain syndromes.

Theoretical Framework

The Defecation List is grounded in modern neurogastroenterological theory, the biopsychosocial model of medicine pioneered by George Engel, and the empirical paradigm of Ecological Momentary Assessment (EMA). Traditional biomedical approaches treated lower gastrointestinal dysfunction as an isolated biomechanical or biochemical disorder of the colon and rectum. However, contemporary neurogastroenterology conceptualizes bowel function as a continuous, dynamic dialogue between the central nervous system, the autonomic nervous system, the enteric nervous system, and pelvic striated musculature.

According to the cognitive-behavioral model of functional anorectal disorders, maladaptive bowel habits develop and persist through a cyclical feedback loop. Experiencing painful defecation (due to hard stool or anal fissures) or episodes of embarrassing fecal incontinence induces autonomic arousal and selective somatic attention. This anxiety elicits anticipatory hypertonicity of the pelvic floor musculature (levator ani and puborectalis muscles). When the individual next attempts defecation, the striated pelvic floor fails to relax or contracts paradoxically (anorectal dyssynergia), leading to outlet obstruction, severe straining, and perceived incomplete emptying. Frustration and panic reinforce hypervigilant self-monitoring, which further exacerbates visceral hypersensitivity and dysregulated motility.

Within the EMA paradigm, prospective event-contingent behavioral monitoring serves two fundamental theoretical mandates:

1. Minimization of Cognitive Reconstruction: Retrospective questionnaires require respondents to synthesize memories across extended periods, relying on the ‘peak-end rule’—where subjective evaluations are disproportionately dominated by the most emotionally intense moment and the most recent moment of an experience. The Defecation List mandates logging each discrete event immediately upon occurrence in naturalistic living conditions, thereby capturing true baseline ecological variance and eradicating retrospective cognitive reconstruction.
2. Contextual and Temporal Interdependence: By recording sequential variables within each discrete defecatory episode (urgency → consistency → straining → post-evacuation tenesmus → pain), the Defecation List allows clinicians and researchers to analyze how physiological variables (e.g., Bristol Type 1 consistency) dynamically interact with behavioral variables (straining) and subjective pain ratings at an idiographic, micro-longitudinal level.

Validity

The psychometric validity of prospective defecation diaries, specifically the standardized Dutch Defecatielijst endorsed by the Royal Dutch Society for Physical Therapy (KNGF) and international equivalents developed by Rao and colleagues, has been extensively demonstrated across several validity domains:

Content and Face Validity

Content validity was established through formal Delphi consensus panels comprising leading neurogastroenterologists, colorectal surgeons, and specialized pelvic floor physical therapists (Bols et al., 2011; Rao, 2004). Panelists confirmed that the eight operationalized parameters encompass all clinically mandatory diagnostic features established by the international Rome Foundation (Rome IV diagnostic criteria) for Functional Constipation, Irritable Bowel Syndrome with Constipation (IBS-C), Dyssynergic Defecation, and Fecal Incontinence. High face validity is documented among adult and elderly respondents, who consistently rate the tool as intuitively logical and representative of their symptomatic reality.

Criterion and Concordant Validity

Extensive criterion validation has evaluated the concordance between diary entries and objective laboratory diagnostics:

• Colonic Transit Correlation: Stool consistency recorded on the embedded Bristol Stool Form Scale correlates significantly with objective radiopaque marker transit studies (Hinton method) and wireless motility capsule (SmartPill) colonic transit times (Spearman’s r = -0.55 to -0.68, p < 0.001). Higher BSFS ratings (loose stool) consistently mirror accelerated radiologically determined colonic transit, whereas lower ratings (Types 1 and 2) correspond to prolonged segmental retention.
• High-Resolution Anorectal Manometry (HRAM): Prospective diary reports of constant severe straining (Parameter 6) and incomplete evacuation (Parameter 7) correlate strongly with physiological findings of dyssynergic defecation during manometric balloon expulsion testing, exhibiting diagnostic sensitivity exceeding 82% and specificity of 76% (Rao et al., 2004).
• Accidental Bowel Leakage Verification: Prospective diary quantification of involuntary loss (Parameter 5) demonstrates superior criterion validity over retrospective global scoring scales (such as the Wexner/Cleveland Clinic Fecal Incontinence Severity Scale), capturing episodic micro-soiling and liquid seepage that patients systematically fail to aggregate accurately during clinical interviews.

Discriminant and Known-Groups Validity

The Defecation List exhibits robust discriminant validity by reliably distinguishing between healthy asymptomatic controls, patients with slow-transit functional constipation, patients with normal-transit dyssynergic defecation, and patients with primary fecal incontinence. In clinical comparative trials (e.g., Bols et al., 2012), patients with diagnosed anorectal dysfunction demonstrated significantly higher rates of BSFS Type 1–2 stools, significantly greater proportions of incomplete evacuation episodes (68% vs. 12% in controls, p < 0.001), and higher straining prevalence than age- and sex-matched healthy cohorts.

Reliability

Because the Defecation List is structured as an event-level prospective observational log rather than a reflective multi-item psychometric scale, standard internal consistency metrics (such as Cronbach’s alpha or McDonald’s omega) are theoretically inapplicable and inappropriate. The items do not reflect a single underlying unidimensional latent trait; rather, they capture distinct, formatively related clinical occurrences (e.g., an individual may experience severe straining with hard stool in the morning, followed by involuntary liquid soiling in the afternoon). Psychometric evaluation of the instrument therefore centers on test-retest reliability, inter-observer consistency, and diary compliance stability:

Test-Retest Stability Across Observational Epochs

In patients with stable, untreated functional defecation disorders, test-retest reliability was evaluated by comparing consecutive 7-day diary recording periods (Week 1 vs. Week 2). Intraclass correlation coefficients (ICCs) demonstrate high temporal stability for cardinal primary parameters:

• Weekly Bowel Movement Frequency: ICC = 0.84 to 0.92 (95% CI [0.78, 0.95]), indicating outstanding behavioral stability under stationary clinical conditions.
• Mean Bristol Stool Form Scale Score: ICC = 0.79 to 0.87, confirming that physiological transit morphology exhibits strong week-to-week reproducibility in chronic constipation and incontinence cohorts.
• Fecal Incontinence Episodes per Week: ICC = 0.76 to 0.85, confirming reliable reproducibility of Accidental Bowel Leakage metrics over a 14-day observation window.
• Percentage of Straining Evacuations: ICC = 0.71 to 0.80, demonstrating moderate-to-high reproducibility.

Inter-Rater and Scoring Concordance

When completed in institutional or geriatric environments where nursing staff and patients independently or co-operatively complete the Defecation List, inter-rater reliability for objective parameters (time, Bristol Stool Scale rating, and visible involuntary leakage) demonstrates substantial to almost perfect inter-observer agreement, with Cohen’s kappa (κ) coefficients ranging from 0.78 to 0.91.

Compliance and Minimum Observation Duration

Psychometric investigations into optimal diary duration show that a 7-day prospective recording protocol yields optimal trade-offs between measurement precision and respondent compliance. Diary completion rates remain exceptionally high (>90%) throughout the first 7 days, but decline sharply after 14 consecutive days due to participant cognitive fatigue and log burden. Thus, the KNGF guidelines and international neurogastroenterology consensus advocate a 7-to-14-day tracking window.

Factor Analysis

In psychometric theory, a critical distinction exists between reflective measurement models and formative (or composite) clinical indicator models:

The Formative Measurement Model

In standard reflective psychometric scales (such as the Beck Depression Inventory or State-Trait Anxiety Inventory), latent variables are hypothesized to cause the observed item scores, meaning items should correlate highly and load onto identifiable common factors during Exploratory Factor Analysis (EFA) or Confirmatory Factor Analysis (CFA). In contrast, the Defecation List is a formative, event-based clinical registry. Straining, involuntary leakage, stool consistency, and urgency are distinct physiological manifestations that together compose the clinical syndrome of defecatory dysfunction, rather than being caused by a single internal psychological state.

Empirical Latent Structure Investigations

Despite its formative nature, multivariate clustering and structural equation models applied to large-scale prospective bowel diary cohorts (e.g., Rao, 2004; Bols et al., 2012) yield clear, empirically reproducible clinical factor clusters that mirror the Rome IV diagnostic taxonomies:

• Factor 1: Obstructive Defecatory Dysfunction (Outlet Obstruction) — Highly characterized by positive factor loadings on Parameter 6 (Straining, λ = 0.82), Parameter 7 (Feeling of Incomplete Evacuation, λ = 0.78), and negative loadings on Bristol Stool Scale (Types 1–2, λ = -0.65). This factor strongly correlates with manometrically confirmed dyssynergic defecation and pelvic floor non-relaxation.
• Factor 2: Continence Compromise (Incontinence Severity) — Defined by high positive loadings on Parameter 5 (Involuntary Stool Loss, λ = 0.88) and Parameter 2 (Urgency Felt, λ = 0.71), reflecting sphincter insufficiency, reduced rectal compliance, and acute sensory emergency.
• Factor 3: Intestinal Motor Transit Rate — Dominated by Parameter 3 (Bristol Stool Form Scale, λ = 0.89) and Parameter 4 (Amount of Stool, λ = 0.58), reflecting true physiological propulsive velocity along the colon.
• Factor 4: Visceral Hyperalgesia — Captures Parameter 8 (Pain and Cramping, λ = 0.84), which functions orthogonally to purely mechanical parameters, segregating patients with severe irritable bowel syndrome and central somatic amplification from those with uncomplicated biomechanical pelvic floor lesions.

These empirical factor structures confirm that the Defecation List captures multi-dimensional, clinically distinct aspects of pelvic and colonic pathophysiology without redundant item overlap.

Instrument / Measurement Tool

The operational specifications of the Defecation List are structured as follows:

• Instrument Type: Prospective event-based observational monitoring log / Ecological Momentary Assessment (EMA) diary. Available in physical paper booklet or structured digital/electronic application format.
• Target Population: Adults (18–64 years) and older adults/geriatric patients (≥65 years) undergoing diagnostic evaluation or physical therapy/medical treatment for chronic defecation disorders, constipation, or fecal incontinence.
• Administration Mode: Self-administered by the patient, or completed with the assistance of a designated caregiver/nurse in geriatric or neurorehabilitation settings. Entries must be completed immediately following each defecation, attempted defecation, or involuntary leakage episode.
• Observation Duration: 7 to 14 consecutive calendar days (7 days standard; 14 days recommended for severe or intermittent fecal incontinence).
• Number of Core Operational Parameters: 8 parameters per recorded event.
• Response Scales and Formats:
  • Parameter 1 (Time): Exact timestamp (24-hour clock: HH:MM).
  • Parameter 2 (Urgency): Dichotomous categorical (Ja / Nee; Yes / No).
  • Parameter 3 (Consistency): Categorical ordinal scale based on the Bristol Stool Form Scale (Type 1 to Type 7).
  • Parameter 4 (Stool Volume): 3-point ordinal scale (Weinig / Normaal / Veel; Scanty / Normal / Copious).
  • Parameter 5 (Involuntary Fecal Loss): Categorical classification of leakage morphology (Veeg [Smear/stain] / Vloeibaar [Liquid] / Gevormd [Formed stool]).
  • Parameter 6 (Straining): Dichotomous categorical (Ja / Nee; Yes / No).
  • Parameter 7 (Incomplete Evacuation): Dichotomous categorical (Ja / Nee; Yes / No).
  • Parameter 8 (Pain/Cramping): 4-point ordinal severity scale (Geen [None] / Licht [Mild] / Matig [Moderate] / Ernstig [Severe]).
• Scoring and Interpretation Procedures:
  • No Psychometric Sum Score: There is no single aggregate numerical sum score. The instrument is evaluated through clinical metric profiling across the observation period.
  • Quantitative Summary Metrics:
    • Total Defecation Frequency: Mean number of spontaneous bowel movements per 24-hour period and per week (normal range: 3 per week to 3 per day).
    • Mean Stool Consistency: Average BSFS score and proportion (%) of bowel movements graded as hard/scybalous (Types 1–2) vs. normal (Types 3–4) vs. loose/watery (Types 5–7).
    • Incontinence Rate: Absolute count of involuntary loss episodes per week, broken down by morphology (smear, liquid, formed).
    • Outlet Obstruction Index: Percentage of total defecation events accompanied by severe straining (>25% indicates obstruction under Rome IV) and incomplete evacuation.
    • Pain Index: Percentage of events characterized by moderate-to-severe peridefecatory pain.

Permissions & Fee and Test Year

The conceptual origin of modern prospective defecation recording protocols in gastrointestinal neurogastroenterology is attributed to Satish S. C. Rao (published in 2004). The standardized Dutch clinical instrument—the Defecatielijst (and associated explanatory documentation / Toelichtingsformulier)—was formalized in 2011 by Esther Bols and the Pelvic Floor Guideline Development Committee of the Royal Dutch Society for Physical Therapy (Koninklijk Nederlands Genootschap voor Fysiotherapie; KNGF) within the standard clinical measurement toolbox (Meetinstrumenten KNGF).

Licensing and Accessibility: The Defecatielijst is in the public domain for clinical, educational, and academic research purposes. It is published open-access in Dutch healthcare repositories and professional medical practice guidelines without licensing fees. Clinicians, physical therapists, and researchers are permitted to reproduce and administer the form on paper or integrate its parameters into secure, compliant digital health electronic medical records (EMR) and specialized mobile smartphone logging platforms, provided that proper academic citation is maintained.

References

The academic validation and clinical implementation of the Defecation List are documented across the following peer-reviewed literature:

• Bols, E. M., Hendriks, H. J., Berghmans, B. C., Baeten, C. G., & de Bie, R. A. (2011). KNGF-richtlijn Motorische vaardigheden en bekkenbodemdysfuncties: Fysiotherapie bij patiënten met ongewild urine- en ontlastingsverlies [KNGF Clinical Practice Guideline for Physical Therapy in patients with accidental urine and fecal leakage]. Koninklijk Nederlands Genootschap voor Fysiotherapie (KNGF). https://www.kngf.nl
• Bols, E. M., Hendriks, H. J., Berghmans, L. C., Baeten, C. G., Nijhuis, J. G., & de Bie, R. A. (2012). Responsiveness and interpretability of pelvic floor muscle training outcome measures in patients with fecal incontinence. Physical Therapy, 92(1), 74–84. https://doi.org/10.2522/ptj.20110029
• Lewis, S. J., & Heaton, K. W. (1997). Stool form scale as a useful guide to intestinal transit time. Scandinavian Journal of Gastroenterology, 32(9), 920–924. https://doi.org/10.3109/00365529709011203
• Mearin, F., Lacy, B. E., Chang, L., Chey, W. D., Lembo, A. J., Simren, M., & Spiller, R. (2016). Bowel disorders. Gastroenterology, 150(6), 1393–1407. https://doi.org/10.1053/j.gastro.2016.02.031
• Rao, S. S. (2004). Diagnosis and management of exit dysfunction constipation. Current Gastroenterology Reports, 6(4), 279–284. https://doi.org/10.1007/s11894-004-0077-8
• Rao, S. S., Ozturk, R., & Stessman, M. (2004). Investigation of the utility of colorectal diagnostic tests in evaluating severe constipation. The American Journal of Gastroenterology, 99(11), 2201–2209. https://doi.org/10.1111/j.1572-0241.2004.40428.x
• van der Horst, H. E., & de Wit, N. J. (2014). NHG-Standaard Obstipatie (M87) [Dutch College of General Practitioners Clinical Standard for Constipation]. Huisarts en Wetenschap, 57(9), 470–480.

Items of the Scale