CMS publishes the complete MCC and CC lists as part of the FY 2026 IPPS Final Rule supporting tables. Specifically, the FY 2026 final-rule page identifies Table 6I as the Complete MCC List and Table 6J as the Complete CC List, along with additions, deletions, and the CC exclusion list.

These files are critical reference resources when assessing MS-DRG severity logic. Nevertheless, classification as an MCC or CC does not automatically mean that the diagnosis changes a particular case's MS-DRG. Principal-diagnosis exclusions, procedure logic, DRG structure, and the presence of another MCC can affect whether a diagnosis alters final assignment.

The Hospital Consumer Assessment survey relates to patient experience rather than diagnosis severity classification. The Physician Fee Schedule governs professional reimbursement and does not contain the inpatient MS-DRG MCC/CC classification system. National Coverage Determinations address Medicare coverage for particular services rather than MS-DRG severity categories.

CDI specialists should use the current CMS version applicable to the discharge date. CMS identifies MS-DRG Version 43.1 as effective April 1 through September 30, 2026.

CCDS Reference Topics: MCC; CC; CMS Definitions Manual; IPPS; MS-DRG severity.

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When a pressure ulcer progresses to a higher stage during an inpatient stay, ICD-10-CM instructs reporting that preserves both its stage at admission and the highest stage reached during hospitalization.

Therefore, the stage 3 condition present at admission and subsequent progression to stage 4 must both be represented according to the applicable coding instructions.

This approach accurately portrays both the patient's baseline condition and deterioration after admission. Reporting only stage 4 would lose important POA information, while reporting only stage 3 would fail to capture the subsequent clinical severity.

An unstageable pressure-ulcer code is not appropriate simply because the wound changed stages. “Unstageable” has a specific clinical meaning—typically the true depth cannot be determined because the wound base is obscured by slough or eschar or another specified circumstance.

CDI review should ensure documentation includes wound location, stage, laterality when applicable, timing of progression, and relevant wound-care assessment. Qualified wound clinicians may provide pressure-ulcer staging information under applicable non-provider documentation rules.

CCDS Reference Topics: Pressure ulcers; progression; POA; wound staging; quality reporting.

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CMS specifically includes deep vein thrombosis and pulmonary embolism following certain orthopedic procedures, including total knee replacement and hip replacement, among Hospital-Acquired Conditions subject to the HAC/POA payment provisions. Therefore, option C is correct.

Under the IPPS HAC payment policy, qualifying conditions that were not present on admission may lose their normal CC/MCC effect for MS-DRG assignment when all applicable criteria are met. This makes accurate POA determination essential in CDI and coding.

Pressure ulcers are also part of the HAC framework, but the CMS category historically applies specifically to Stage III and Stage IV pressure ulcers. An unstageable pressure ulcer does not automatically satisfy the Stage III/IV HAC category merely because it is severe or clinically significant. CMS materials distinguish an unstageable ulcer from a documented Stage III or IV ulcer.

Postoperative pneumonia and septic shock are not, by themselves, the specified HAC category represented by the answer choices.

The CCDS blueprint specifically requires candidates to identify CMS-designated HACs and understand the effect of POA assignment on payment.

CCDS Reference Topics: IPPS; Hospital-Acquired Conditions; POA; MS-DRG adjustment.

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Pulmonary vascular congestion accompanied by pleural effusions is classically associated with congestive heart failure, particularly left-sided or biventricular decompensation. Increased left-sided cardiac filling pressure raises pulmonary venous and capillary hydrostatic pressure, promoting interstitial and alveolar fluid accumulation. Fluid may also migrate into the pleural space, producing unilateral or bilateral pleural effusions.

Additional radiographic indicators of heart failure may include cardiomegaly, cephalization of pulmonary vessels, interstitial edema, Kerley B lines, perihilar alveolar opacities, and bilateral effusions. These findings should always be interpreted alongside symptoms and other clinical evidence such as dyspnea, orthopnea, edema, BNP/NT-proBNP, echocardiography, and response to diuretics.

COPD more commonly demonstrates hyperinflation, flattened diaphragms, and increased lucency rather than pulmonary vascular congestion. Cor pulmonale refers to right-sided cardiac dysfunction resulting from pulmonary disease and does not typically produce the classic pulmonary venous congestion pattern. Pulmonary embolism may have a normal chest radiograph or nonspecific abnormalities, but pulmonary vascular congestion with effusions is not its characteristic pattern.

For CDI purposes, imaging provides a clinical indicator but does not independently establish the diagnosis or acuity of heart failure.

CCDS Reference Topics: Heart failure pathophysiology; chest radiography; clinical indicators; cardiopulmonary terminology.

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The CDI specialist should clarify the clinical significance and relationship to the procedure. Not every condition occurring after surgery constitutes a complication of care, and mechanical ventilation itself does not establish postoperative respiratory failure.

Major operations often require planned postoperative ventilatory support because of anesthesia, surgical duration, hemodynamic status, or other expected recovery needs. Conversely, unexpected inability to extubate, severe hypoxemia or hypercapnia, escalating ventilatory support, or other clinical deterioration may support a genuine postoperative respiratory complication.

ICD-10-CM complication reporting requires careful attention to provider documentation of the relationship between the condition and the procedure. The FY 2026 Official Guidelines emphasize that the fact a condition occurs after a procedure is not, by itself, sufficient to classify it as a complication.

Option A therefore assumes a complication that may not exist. Option C improperly alters provider documentation without clarification. Option D mistakes treatment for diagnosis.

A compliant query should objectively present respiratory findings, duration of ventilation, reintubation or escalation when present, and the operative/anesthesia documentation, then allow the provider to characterize the condition.

CCDS Reference Topics: Postoperative respiratory failure; complications of care; mechanical ventilation; clinical validation.

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The CDI specialist should query the provider regarding the cause-and-effect relationship between the urinary catheter and the infection. The simultaneous presence of a catheter and UTI does not, by itself, establish a device-related complication for coding.

A positive culture, pyuria, and fever may support infection, but attribution to an indwelling catheter requires appropriate provider documentation when the classification does not independently establish the relationship.

The query should present relevant facts neutrally: catheter placement and duration, fever, urinary symptoms when present, urinalysis, culture findings, antibiotic treatment, and existing UTI documentation. Possible responses should allow the physician to identify catheter-associated UTI, UTI unrelated to the catheter, another diagnosis, or inability to determine.

Option A improperly infers causation. Option C goes too far in the opposite direction; although asymptomatic bacteriuria is common in catheterized patients, the provider has documented UTI and the patient has clinical findings that may support infection. Option D similarly equates a test result with a complication diagnosis.

This is a classic CCDS cause-and-effect clarification issue and demonstrates why device-related complications require careful documentation.

CCDS Reference Topics: CAUTI; device-related complications; cause-and-effect queries; clinical indicators; quality reporting.

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A query becomes problematic when it directs or influences the provider toward a diagnosis that is not supported by the patient's clinical record. Therefore, option C most accurately represents the leading-query concept in this answer set. A compliant query must be based on patient-specific clinical indicators and must preserve the provider's independent clinical judgment.

A multiple-choice query may include a diagnosis not previously documented when that diagnosis is supported by the clinical indicators and when reasonable alternatives are also offered. ACDIS/AHIMA guidance has specifically recognized that presenting a clinically supported new diagnosis among neutral choices does not automatically make the query leading.

Likewise, the timing of a query while a provider is documenting does not make it leading. Cause-and-effect clarification may also be addressed using an appropriate query format when both conditions are documented and the relationship remains uncertain.

The current 2026 ACDIS/AHIMA Guidelines for Achieving a Compliant Query Practice supersede the prior versions and continue to establish compliant provider-query practice as a foundational CDI standard. Queries must be clinically supported, noncoercive, and constructed without reference to reimbursement or other desired outcomes.

CCDS Reference Topics: Leading queries; clinical indicators; compliant query construction; provider independence.

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The documentation does not clearly establish the definitive condition chiefly responsible for the inpatient admission. The patient has chest pain, borderline troponin elevation, and a history of GERD, while the physician describes the symptoms only as “likely GI in origin.” The appropriate CDI action is therefore to clarify the condition responsible for the admission rather than independently select GERD or myocardial infarction.

A history of GERD does not establish that GERD caused the present chest pain. Likewise, borderline troponin elevation alone does not establish an AMI, so a query that directs the provider toward AMI would be inappropriate without stronger clinical support.

For inpatient coding, uncertain diagnoses documented at discharge using terms such as “probable,” “suspected,” or “likely” may be coded as though established. However, the phrase “GI in origin” still fails to identify a specific gastrointestinal disease responsible for the admission. The CDI specialist's purpose is to obtain clinically meaningful diagnostic clarification rather than infer a diagnosis from treatment such as omeprazole.

A compliant query should include the relevant symptoms, diagnostic findings, treatment, and supported alternatives without indicating financial consequences.

CCDS Reference Topics: Principal diagnosis clarification; ambiguous documentation; compliant querying; clinical indicators.

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Among the listed diagnoses, acute diastolic heart failure has the greatest potential MS-DRG impact because ICD-10-CM code I50.31 is classified as an MCC under the FY 2026 CMS MS-DRG system. CMS specifically identifies I50.31 as an MCC, whereas diagnoses classified only as a CC generally produce a lower severity level within DRG families that distinguish no CC/MCC, CC, and MCC cases.

Acute kidney injury, commonly represented by N17.9 when unspecified, is generally a CC rather than an MCC; CMS examples demonstrate N17.9 functioning as a CC in MS-DRG assignment. COPD with acute exacerbation and many delirium diagnoses may also affect severity assignment, but they do not exceed the MCC effect of qualifying acute heart failure in the standard hierarchy represented here.

The wording “monetary impact” must not be interpreted as permission to pursue diagnoses for financial gain. CDI professionals should query only when clinical indicators justify clarification. Reimbursement is a consequence of accurate documentation and coding, not the clinical justification for creating a diagnosis.

The actual payment impact also depends on the principal diagnosis, existing MCCs, procedures, payer methodology, and final MS-DRG.

CCDS Reference Topics: CC/MCC hierarchy; MS-DRG reimbursement; acute heart failure; compliant CDI practice.

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The most compliant approach is to present the patient-specific clinical indicators objectively and request clarification using clinically reasonable choices without predetermining the diagnosis.

Neither the CDI specialist nor coder independently diagnoses sepsis from fever, leukocytosis, tachycardia, cultures, or antibiotic therapy. These findings create a legitimate clarification opportunity, but the responsible provider must determine whether the patient has sepsis, bacteremia, a localized infection, contamination, another condition, or no definitive diagnosis.

Option A is leading because it instructs the provider to document a specific diagnosis. Option B is problematic because a yes/no format would effectively introduce a new diagnosis that has not previously been documented. Option D violates basic coding principles because treatment alone does not establish a provider diagnosis.

The August 2026 ACDIS/AHIMA guidance is the current foundational standard for compliant query practice and supersedes earlier versions. It applies across inpatient and other healthcare environments and emphasizes defensible documentation clarification processes.

CCDS Reference Topics: Compliant queries; missing diagnosis; multiple-choice queries; clinical indicators; provider independence.

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