2027 ICD-10-CM Diagnosis Code N99.518Other cystostomy complication
ICD-10-CM Codes›N00–N99›N99›N99
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
N99.518 is a billable ICD-10-CM diagnosis code for other cystostomy complication. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 698 through 700. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 189 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Postprocedural or postoperative genitourinary system complication.
N99.518 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 176 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 176, ESRD (V21) category 176, and ESRD (V24) category 176 for payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
N99.518 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to N99.518: its own notes plus those printed at N99.5, N99, and Chapter 14. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- mechanical complication of urinary catheter (T83.0-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name N99.518, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming N99.518: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 6
These codes carry an Excludes2 note naming N99.518: its condition is not part of those codes, and both may be reported when the patient has both.
- Block T80-T88 Complications of surgical and medical care, not elsewhere classifiedintraoperative and postprocedural complications of specified body systems (D78.-, E36.-, E89.-, G97.3-, G97.4, H59.3-, H59.-, H95.2-, H95.3, I97.4-, I97.5, J95.6-, J95.7, K91.6-, L76.-, M96.-, N99.-) names N99.-, which includes this code
- Block T80-T88 Complications of surgical and medical care, not elsewhere classifiedostomy complications (J95.0-, K94.-, N99.5-) names N99.5-, which includes this code
- T81 Complications of procedures, not elsewhere classifiedintraoperative and postprocedural complications of specific body system (D78.-, E36.-, E89.-, G97.3-, G97.4, H59.3-, H59.-, H95.2-, H95.3, I97.4-, I97.5, J95, K91.-, L76.-, M96.-, N99.-) names N99.-, which includes this code
- T81 Complications of procedures, not elsewhere classifiedostomy complications (J95.0-, K94.-, N99.5-) names N99.5-, which includes this code
- T83.0 Mechanical complication of urinary cathetercomplications of stoma of urinary tract (N99.5-) names N99.5-, which includes this code
- T83.51 Infection and inflammatory reaction due to urinary cathetercomplications of stoma of urinary tract (N99.5-) names N99.5-, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
cystostomy (stoma) N99.518
specified type NEC N99.518
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Ostomy
An ostomy is surgery to create an opening (stoma) from an area inside the body to the outside. It treats certain diseases of the digestive or urinary systems. It can be permanent, when an organ must be removed. It can be temporary, when the organ needs time to heal. The organ could be the small intestine, colon, rectum, or bladder.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert N99.518 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N99.518Overview
What is the ICD-10 code for other cystostomy complication?
The ICD-10-CM code for other cystostomy complication is N99.518 (sometimes written as N99518). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is N99.518 (Complication of cystostomy) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other cystostomy complication on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does N99.518 group to?
When other cystostomy complication is the principal diagnosis on an inpatient stay, it groups to MS-DRG 699, 698, 700, with relative weights from 0.6740 to 1.6400 depending on complications. Higher weights mean higher Medicare reimbursement.
Is N99.518 a CC or MCC?
CMS lists N99.518 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 189 closely related codes in its exclusion list.
What is the ICD-9 equivalent of N99.518?
Under the General Equivalence Mappings, other cystostomy complication converts to ICD-9-CM 596.83 (other comp of cystostomy). The mapping is approximate, so confirm the match fits the documentation.
Does N99.518 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. N99.518 mapped to HCC 176 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 176 (Complications of Specified Implanted Device or Graft), ESRD (V21) category 176 (Complications of Specified Implanted Device or Graft), and ESRD (V24) category 176 (Complications of Specified Implanted Device or Graft).
