Constipation ICD-10 coding is a standardized medical classification system used to document, diagnose, bill, and analyze constipation-related healthcare encounters in the United States. ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification) is maintained by the Centers for Disease Control and Prevention (CDC) and is mandatory for all HIPAA-covered entities.
Constipation is not a single disease entity. It is a clinical condition with multiple causes, presentations, and severities. Accurate ICD-10 coding ensures proper reimbursement, clinical clarity, epidemiological tracking, and continuity of care.
What Is Constipation in Clinical Terms?
Medical Definition
Constipation is clinically defined as infrequent bowel movements, difficult stool passage, or a sensation of incomplete evacuation. In adults, fewer than three bowel movements per week is commonly used as a diagnostic threshold, though patient experience is central to diagnosis.
Common Clinical Features
- Hard or lumpy stools
- Excessive straining
- Sensation of anorectal blockage
- Manual maneuvers to facilitate defecation
- Reduced stool frequency
Constipation may be acute, chronic, functional, medication-induced, or secondary to systemic disease.
ICD-10 Overview for Constipation
Primary ICD-10 Code for Constipation
K59.00 – Constipation, unspecified
This is the most frequently used ICD-10 code when documentation does not specify the type or cause of constipation.
Detailed Constipation ICD-10 Code List
Primary Constipation Codes (K59 Category)
K59.00 – Constipation, unspecified
Used when constipation is documented without further detail.
K59.01 – Slow transit constipation
Applies when delayed colonic transit is confirmed or strongly suspected.
K59.02 – Outlet dysfunction constipation
Used for defecatory disorders involving pelvic floor dyssynergia.
K59.09 – Other constipation
Used when constipation is specified but does not fit other subtypes.
Secondary and Related ICD-10 Codes
Drug-Induced and Functional Associations
- K59.03 – Drug-induced constipation
Commonly associated with opioids, anticholinergics, iron, and calcium supplements. - K59.04 – Chronic idiopathic constipation
Used when constipation persists without identifiable structural or metabolic cause.
Chronic vs Acute Constipation Coding
Chronic Constipation
Chronic constipation is generally defined as symptoms lasting longer than three months. ICD-10 coding requires documentation of duration and persistence.
Common codes:
- K59.04 – Chronic idiopathic constipation
- K59.01 – Slow transit constipation
Acute Constipation
Acute constipation is usually transient and secondary to diet, dehydration, or medications. Often coded as:
- K59.00 – Constipation, unspecified
Pediatric Constipation ICD-10 Coding
Common Pediatric Codes
- K59.00 – Used when no further detail is provided
- R15.9 – Fecal incontinence, unspecified (when present)
Pediatric constipation often involves functional withholding behavior and requires careful documentation to avoid undercoding.
Constipation ICD-10 Coding in Medical Billing
Importance for Reimbursement
Accurate constipation ICD-10 coding affects:
- Claim approval rates
- Risk adjustment scoring
- Medical necessity validation
Underspecified coding (e.g., overuse of K59.00) may trigger payer audits.
Coding Best Practices
- Document chronicity clearly
- Identify medication causes when applicable
- Link constipation to underlying conditions when relevant
Diagnostic Evaluation Supporting ICD-10 Coding
Clinical Evaluation
- History and physical examination
- Digital rectal exam
- Medication review
Diagnostic Testing (When Indicated)
- Colon transit studies
- Anorectal manometry
- Colonoscopy (alarm features only)
Unique Clinical Takeaways
1. Patient-Reported Experience Drives Accurate Coding
Constipation severity does not correlate reliably with stool frequency alone. Patients with daily bowel movements may still meet criteria for outlet dysfunction constipation due to incomplete evacuation. Coding should reflect documented patient experience, not numerical frequency alone.
2. Misclassification Leads to Treatment Failure
Slow transit constipation (K59.01) and outlet dysfunction constipation (K59.02) require different management strategies. Incorrect ICD-10 selection may result in ineffective treatment, repeat visits, and unnecessary laxative escalation.
3. Drug-Induced Constipation Is Underreported
Drug-induced constipation (K59.03) is frequently miscoded as unspecified constipation. Failure to document medication causality can obscure adverse drug effects and impact pharmacovigilance reporting.
4. Chronic Idiopathic Constipation Is a Diagnosis of Exclusion
K59.04 should only be used after metabolic, neurologic, and structural causes are reasonably excluded. Premature use of this code can delay identification of serious underlying conditions.
Constipation ICD-10 and Differential Diagnosis
Conditions that must be considered before final coding:
- Irritable bowel syndrome with constipation (K58.1)
- Intestinal obstruction (K56.x)
- Hypothyroidism (E03.x)
- Parkinson disease (G20)
- Colorectal malignancy (C18–C20)
Documentation Tips for Clinicians
- Specify duration (acute vs chronic)
- Identify causative medications
- Note alarm symptoms (weight loss, anemia, bleeding)
- Record functional impact on daily life
Common ICD-10 Coding Errors
- Defaulting to K59.00 without clarification
- Coding IBS-C as constipation
- Ignoring medication-induced etiology
- Using chronic codes for short-term symptoms
ICD-10 Constipation Coding in Value-Based Care
Constipation coding influences:
- Quality metrics
- Risk stratification
- Care coordination in elderly and chronic disease populations
Accurate coding improves population health analytics and patient outcomes.
Medical Disclaimer
This content is intended for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Clinical decisions should be made by licensed healthcare professionals based on individual patient evaluation and current clinical guidelines.