Other functional intestinal disorders (K59) ICD-10-CM
The K59 code range covers other functional intestinal disorders with 18 ICD-10-CM diagnosis codes. 14 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
- functional disorders of stomach K31
Codes in the K59 Range 18 codes · 14 billable
- K59 Other functional intestinal disordersNon-billable
- K59.0 ConstipationNon-billable
- K59.00 Constipation, unspecified
- K59.01 Slow transit constipation
- K59.02 Outlet dysfunction constipation
- K59.03 Drug induced constipation
- K59.04 Chronic idiopathic constipation
- K59.09 Other constipation
- K59.1 Functional diarrhea
- K59.2 Neurogenic bowel, not elsewhere classified
- K59.3 Megacolon, not elsewhere classifiedNon-billable
- K59.31 Toxic megacolon
- K59.39 Other megacolon
- K59.4 Anal spasm
- K59.8 Other specified functional intestinal disordersNon-billable
- K59.81 Ogilvie syndrome
- K59.89 Other specified functional intestinal disorders
- K59.9 Functional intestinal disorder, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the K59 range.
Constipation
Infrequent or difficult evacuation of FECES. These symptoms are associated with a variety of causes, including low DIETARY FIBER intake, emotional or nervous disturbances, systemic and structural disorders, drug-induced aggravation, and infections.
Encopresis
Incontinence of feces not due to organic defect or illness.
Hirschsprung Disease
Congenital MEGACOLON resulting from the absence of ganglion cells (aganglionosis) in a distal segment of the LARGE INTESTINE. The aganglionic segment is permanently contracted thus causing dilatation proximal to it. In most cases, the aganglionic segment is within the RECTUM and SIGMOID COLON.
Megacolon
Dilatation of the COLON, often to alarming dimensions. There are various types of megacolon including congenital megacolon in HIRSCHSPRUNG DISEASE, idiopathic megacolon in CONSTIPATION, and TOXIC MEGACOLON.
Megacolon, Toxic
An acute form of MEGACOLON, severe pathological dilatation of the COLON. It is associated with clinical conditions such as ULCERATIVE COLITIS; CROHN DISEASE; AMEBIC DYSENTERY; or CLOSTRIDIUM ENTEROCOLITIS.
Neurogenic Bowel
Loss or absence of normal intestinal function due to nerve damage or birth defects. It is characterized by the inability to control the elimination of stool from the body.
Opioid-Induced Constipation
CONSTIPATION associated with the use of OPIOIDS.
Sick Sinus Syndrome
A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.
About the K59 Code Range
The K59 ICD-10 codes classify various functional intestinal disorders that affect how the intestines function without obvious structural causes. These codes cover specific conditions like constipation, functional diarrhea, neurogenic bowel, megacolon, anal spasm, and other motility-related intestinal issues.
These codes are used to document and differentiate conditions such as constipation (K59.0), including slow transit constipation (K59.01), outlet dysfunction constipation (K59.02), and drug-induced constipation (K59.03). The term "constipation" here also includes synonyms like obstipation and therapeutic opioid-induced constipation. Functional diarrhea is captured under code K59.1. Neurogenic bowel, which refers to bowel dysfunction caused by nervous system disorders, is coded as K59.2. Cases of megacolon without another classification, including toxic megacolon, are found under K59.3. Anal spasms, often referred to as anismus or painful spasms of the anus, are classified as K59.4. The category also includes other specified functional intestinal disorders such as Ogilvie syndrome (K59.81) and other pseudo-obstruction disorders (K59.89). When the disorder is unspecified, K59.9 applies, covering general functional bowel dysfunction and related symptoms. These detailed subcodes help medical professionals accurately identify and code specific intestinal motility and functional disorders in clinical and billing records.
Questions About This Page
How many billable codes are in the K59 range?
Of the 18 codes in this range, 14 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the K59 range classify?
The range classifies other functional intestinal disorders. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
