Chronic constipation isn’t just a patient discomfort—it’s a billing and coding challenge for many practices. Whether you’re a gastroenterologist, primary care physician, or urgent care provider, accurate Chronic Constipation ICD-10 coding for constipation can make the difference between getting paid on time and getting buried under denials.

In this guide, we’ll break down the ICD-10 codes for chronic constipation, how to document them correctly, and the billing rules you need to follow. We’ll also cover common coding mistakes, payer-specific requirements, and compliance tips to keep your revenue flowing.

Understanding Chronic Constipation in ICD-10

ICD-10 codes help translate a patient’s diagnosis into a standardized billing language for insurers.

Chronic constipation falls under Chapter XI: Diseases of the Digestive System (K00–K95), specifically in Category K59 – Other functional intestinal disorders.

Here are the most common ICD-10 codes:

ICD-10 Code	Description
K59.00	Constipation, unspecified
K59.01	Slow transit constipation
K59.02	Outlet dysfunction constipation
K59.09	Other constipation
K59.1	Functional diarrhea (for differential diagnosis cases)
K59.2	Neurogenic bowel, not elsewhere classified

If you know the cause or type of constipation (like slow transit or outlet dysfunction), use the more specific code instead of K59.00. Payers prefer specificity—it often prevents claim delays.

When to Use Chronic vs. Acute Constipation Codes

One common point of confusion in constipation coding is whether ICD-10 distinguishes between acute and chronic cases.

Here’s the reality: ICD-10 does not have a specific “acute constipation” code. All constipation codes fall under K59.x in the “Other Functional Intestinal Disorders” category. That means the same family of codes is used for both short-term and long-term cases.

So how do you signal chronicity to payers?

·   Use the most specific K59.x code available (e.g., K59.01 for slow transit constipation, K59.02 for outlet dysfunction).

· Document symptom duration in your encounter notes — typically, “chronic” means 3 months or longer according to most GI and payer guidelines.

·  Include any failed conservative management in your documentation (diet changes, hydration, fiber supplements, OTC laxatives).

Why does this matter?

·  For short-term cases (e.g., post-surgery, travel-related), payers rarely require proof of chronicity.

·  For long-standing cases (3+ months), some insurers may require documentation of persistent symptoms before approving advanced tests, procedures, or prescription drugs like lubiprostone or linaclotide.

·   Chronic cases are often linked to comorbidities (Parkinson’s, hypothyroidism, opioid use), so pairing codes appropriately supports medical necessity.

Example:

·  Acute scenario: “Patient reports no bowel movement for 5 days after travel.” → Likely K59.00 with short symptom history documented.

·   Chronic scenario: “Patient reports 2 bowel movements per week for 6 months, with straining and incomplete evacuation despite fiber supplementation.” → K59.01 or other specific code, plus clear chronicity in the note.

Documentation Requirements for Chronic Constipation

To support medical necessity, your documentation should include:

·  Onset & Duration: When symptoms started and how long they’ve persisted.

·  Frequency: How often the patient has bowel movements.

·    Severity & Impact: Pain, bloating, straining, incomplete evacuation.

·   Underlying Cause: Medications, neurological issues, diet, IBS, etc.

·   Failed Treatments: Laxatives, fiber supplements, hydration, diet changes.

·   Associated Conditions: Diabetes, Parkinson’s, hypothyroidism, opioid-induced constipation.

Example: “Patient reports 2 bowel movements per week for the past 4 months, with straining and hard stools. Symptoms not relieved by OTC laxatives. Likely slow transit constipation due to Parkinson’s disease.”

Billing Guidelines for Chronic Constipation ICD-10 Codes

When billing for chronic constipation:

Use the Most Specific ICD-10 Code

Chronic constipation doesn’t have a single “catch-all” ICD-10 code. You need to select the code that best describes the patient’s documented condition.

·   K59.09 – Other constipation → Often used for chronic constipation when not otherwise specified.

·   K59.04 – Chronic idiopathic constipation → When the cause is unknown and meets chronic criteria (≥ 3 months).

·   K59.01 – Slow transit constipation → If motility studies confirm slow colonic transit.

·    K59.02 – Outlet dysfunction constipation → When pelvic floor or anorectal dysfunction is documented.

Tip: Avoid using K59.00 (Constipation, unspecified) unless no further detail is available in documentation.

Link to Medical Necessity

Payers need proof that the diagnosis supports the billed service or procedure.

·   Include the onset date and documentation showing the chronic nature.

·  Describe symptoms (e.g., < 3 bowel movements/week, straining, hard stools) and impact on quality of life.

·   Reference diagnostic results (e.g., colon transit studies, anorectal manometry).

Pair ICD-10 Codes with the Right CPT/HCPCS Codes

Common CPT codes for constipation-related care:

·  99213–99215 → Office visits (established patient)

·  91122 → Anorectal manometry

·  91120 → Rectal sensation/tone testing

·   91110 → GI motility studies

When ordering procedures, ensure that the diagnosis pointers in the claim match the medical reason for the test.

Document Chronicity Clearly

Medicare and commercial payers expect “chronic” to be documented as:

·   Duration ≥ 3 months

·   Ongoing or recurrent symptoms despite interventions

·   Not resolved with short-term treatment

Follow Payer-Specific LCDs and Coverage Rules

Some MACs (Medicare Administrative Contractors) have Local Coverage Determinations for GI motility and constipation testing.

·   Review LCD requirements before billing.

·   Some require failed conservative management before approving advanced diagnostics.

·   Attach modifier -GA when issuing an ABN (Advance Beneficiary Notice) for non-covered services.

Avoid Common Denial Triggers

·   Unspecified codes without supporting documentation.

·  Missing duration or symptom details.

·  CPT/ICD-10 mismatch (e.g., using acute constipation codes for chronic testing).

·  Lack of prior treatment history in the chart.

Consider Comorbidity Codes

If the patient’s constipation is related to another condition, code both:

·  E11.9 → Type 2 diabetes (if contributing to neuropathy-related constipation)

·  G35 → Multiple sclerosis

·  C18.9 → Colorectal cancer

This helps with risk adjustment and accurate reimbursement.

Common Coding Mistakes to Avoid

Even experienced coders fall into these traps, and they can slow payments or trigger denials:

·  Using K59.00 for every patient – This “unspecified constipation” code is a payer red flag when more specific codes exist.

·   Skipping duration documentation – If you call it “chronic,” you need chart notes proving it’s lasted 3+ months.

·  Forgetting to link the cause – If constipation is medication-induced, add the related T40.xx code for drug classification.

·  Upcoding without proof – Claiming severe or complicated constipation without matching chart notes invites audits.

Billing Tips for Providers

Want faster approvals and fewer denials? Build these habits into your workflow:

1.  Document medical necessity – Include symptom severity, pain, failed conservative treatments, and how it affects daily activities.

2.  Use additional diagnosis codes – Capture comorbidities like diabetes (E11.9) or hypothyroidism (E03.9) to show complexity.

3.  Check payer requirements – Some insurers require conservative treatment attempts before approving colon motility studies or pelvic floor therapy.

4.  Stay on top of ICD-10 updates – Code definitions can change yearly (October 1st), which may affect coverage.

5.  Train your team – Front desk staff, MAs, and billers should know which constipation codes require extra documentation or modifiers.

Conclusion

Billing for chronic constipation isn’t just about picking an ICD-10 code—it’s about making sure documentation, coding, and payer rules all line up. The right chronic constipation ICD-10 code, combined with clear notes on medical necessity, can speed up claims and reduce denials. Small errors can lead to payment delays, so a systematic approach is your best friend.

Swiftcare Billing takes the guesswork out of gastroenterology and chronic care billing. We ensure your codes are spot-on, your claims are clean, and your payments are faster.

Ready to eliminate billing headaches?

Contact us today and focus on patient care while we handle the revenue side.

FAQs

What is the main ICD-10 code for chronic constipation?

The most common code is K59.09 (Other constipation), but the exact code depends on your clinical documentation.

Can I bill chronic constipation as the primary diagnosis?

Yes, if it’s the main reason for the visit. If it’s secondary to another condition, list that primary condition first.

Do I need additional codes for chronic constipation?

Sometimes. If constipation is due to another disease, injury, or medication, you may need to add a secondary ICD-10 code to specify the cause.

Does chronic constipation require a modifier use?

Not for diagnosis coding, but modifiers may apply to procedures related to constipation treatment.

Will Medicare cover chronic constipation treatment?

Yes, if medical necessity is documented and the treatment is within their coverage guidelines. Always check the latest Local Coverage Determinations (LCDs).

What documentation supports chronic constipation billing?

Symptoms duration, failed treatments, diagnostic tests, comorbidities, and impact on daily living should be noted in the patient’s chart.