ICD-10-CM Tabular Index · Chapter 11 · FY 2027 K65–K6A
Diseases of peritoneum and retroperitoneum (K65-K6A) ICD-10-CM
The K65–K6A section covers diseases of peritoneum and retroperitoneum with 27 ICD-10-CM diagnosis codes, of which 21 are billable in fiscal year 2027. The section is organized into the 5 code ranges listed below.
✓ Built from the official CMS FY 2027 datasetEffective Oct 1, 2026 – Sep 30, 2027
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the K65–K6A Code Range
These conditions affect the peritoneum, the lining of the abdominal cavity, the retroperitoneum, or the pelvis. Peritonitis means inflammation of the peritoneum.
K65 separates types of peritonitis, including generalized, spontaneous bacterial, and other or unspecified forms. It also includes peritoneal abscesses. K66 groups other peritoneal disorders, including tissue sticking together after a procedure or infection and blood in the peritoneal cavity. K67 identifies peritoneal disorders in infectious diseases classified elsewhere.
K68 separates retroperitoneal abscesses, scarring, collections of blood, and other disorders. K6A separates pelvic abscesses from other pelvic diseases not classified elsewhere.
FY 2027 changes: The FY 2027 ICD-10-CM update, effective October 1, 2026, added K6A.01, K6A.09 and K6A.8.
Questions About This Page
How many codes are in the K65-K6A range?
The K65-K6A range contains 27 ICD-10-CM diagnosis codes in FY 2027. 21 of them are billable, and the rest are category headers that organize the section.
What conditions does K65-K6A cover?
The range covers diseases of peritoneum and retroperitoneum. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
A "code also" note instructs that two codes may be required to fully describe a condition, but this note does not provide sequencing direction.
if applicable diverticular disease of intestine K57
Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
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.
acute appendicitis with generalized peritonitis K35.2
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.
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
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.
