CCDS Certified Clinical Documentation Specialist Questions and Answers

In the inpatient hospital setting, an uncertain diagnosis documented at discharge using terminology such as possible, probable, suspected, likely, questionable, compatible with, or consistent with may generally be coded as though the condition existed or was established.

Therefore, “possible gram-negative pneumonia” may be coded in accordance with the inpatient uncertain-diagnosis guideline when it remains the final diagnostic conclusion.

The rationale is that inpatient diagnostic evaluation and treatment frequently occur before absolute confirmation is available, and the patient may have been managed as though the suspected disease were present.

This rule is materially different from outpatient coding, where uncertain diagnoses are generally not coded as established and the documented signs, symptoms, or confirmed conditions are reported instead.

The presence of the uncertain terminology alone does not mandate a query. A query would be appropriate if documentation is contradictory, if the diagnosis is clinically unsupported, or if another documentation issue prevents correct code assignment.

CDI specialists need to recognize this inpatient-specific rule because unnecessary queries for “possible” or “probable” diagnoses can create physician burden without improving coding accuracy.

CCDS Reference Topics: Uncertain inpatient diagnoses; discharge documentation; pneumonia; inpatient versus outpatient coding.

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The overall response rate is excellent at 98%, but the fact that only 55% of queries are resolved before discharge indicates a meaningful concurrent-workflow issue.

Concurrent CDI is most effective when clarification occurs while the patient remains hospitalized and the physician has immediate access to the clinical context. Delayed responses can contribute to retrospective work, final-bill holds, coding delays, and administrative escalation.

The CDI manager should determine whether delays cluster by provider, specialty, query type, unit, day of week, discharge timing, or electronic-query process. Other factors may include insufficient notification, physician workflow, poor escalation protocols, or queries being issued too late in the stay.

CMI and MCC volume do not directly measure response timeliness and should not substitute for analysis of the actual operational problem.

Importantly, programs should not pressure physicians into rapid but clinically superficial responses. Query timing initiatives must preserve thoughtful provider judgment and compliant communication.

ACDIS identifies medical-record review, communication, query technique, and data-mining/reporting functions among core CCDS competencies.

CCDS Reference Topics: Query timeliness; concurrent CDI; physician engagement; workflow analysis; program metrics.

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ICD-10-CM permits the NIH Stroke Scale score to be reported from documentation by an appropriate clinician other than the provider responsible for establishing the diagnosis. The underlying stroke diagnosis itself must be appropriately documented by the provider.

This is similar to other specified exceptions such as BMI, pressure-ulcer stage, coma scale values, and certain additional clinical elements for which qualified non-provider documentation may support code assignment.

The exception does not mean that a stroke nurse can independently establish cerebral infarction for coding. Rather, once the provider has documented the stroke, the nurse's formal NIHSS assessment can supply the standardized severity measurement.

This approach recognizes that specially trained clinical professionals routinely collect and document these structured measurements as part of patient care.

If multiple NIHSS values are documented, the applicable coding instructions and timing requirements should be followed rather than simply selecting the highest score because it produces a different code.

For CDI professionals, awareness of these non-provider documentation exceptions prevents unnecessary physician queries while ensuring that important severity information is not lost.

CCDS Reference Topics: NIH Stroke Scale; cerebral infarction; non-provider documentation; coding exceptions; stroke severity.

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CMS's Hospital-Acquired Condition payment provisions include DVT and pulmonary embolism following certain orthopedic procedures, including qualifying hip and knee replacement cases. Consequently, accurate POA determination is important when a DVT occurs during the hospitalization.

If a qualifying HAC diagnosis was not present on admission, CMS's MS-DRG payment methodology may prevent the condition from generating the higher payment that its CC/MCC status would otherwise produce, subject to applicable grouper rules.

The diagnosis is still coded. Hospital-acquired status does not mean the condition disappears from the medical record or claim. The purpose of HAC payment logic is to modify payment treatment for defined conditions rather than suppress their reporting.

Nor does a single qualifying HAC necessarily eliminate the entire hospital payment. It affects how the MS-DRG is calculated in accordance with CMS rules.

CDI specialists should also distinguish the HAC/POA payment provision from the separate HAC Reduction Program. CMS explicitly identifies HACRP as a separate quality-payment program.

CCDS Reference Topics: DVT; orthopedic procedures; POA; HAC payment adjustment; MS-DRG.

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The fracture occurred after inpatient admission as the result of a hospital fall, placing it within CMS's Hospital-Acquired Condition category for Falls and Trauma when the applicable fracture code is included in the HAC code list. CMS's FY 2026 MS-DRG Definitions Manual continues to identify qualifying fracture codes within HAC 05.

The fracture must still be coded; therefore, option D is incorrect. Because it clearly developed after admission, it would not appropriately receive POA indicator “U,” which indicates insufficient documentation to determine whether the condition was present on admission.

For qualifying HAC diagnoses that are not POA, CMS payment logic prevents the hospital from receiving the higher MS-DRG payment that would otherwise result solely from the condition's CC/MCC status. Thus, option B expresses the intended payment effect.

This distinction is central to CDI practice: a hospital-acquired diagnosis does not disappear from the record or coding. It remains reportable for clinical and quality purposes, but certain qualifying HACs are treated differently in MS-DRG payment calculations.

CCDS Reference Topics: HACs; POA indicators; Falls and Trauma; MS-DRG payment adjustment.

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The provider's response should be respected unless new information or a genuine unresolved documentation issue creates a legitimate reason for additional clarification.

“Clinically unable to determine” is an acceptable professional conclusion when the available evidence does not permit the provider to confidently establish a diagnosis. A CDI specialist must not continue sending essentially the same query simply because a different response would produce more favorable reimbursement.

Likewise, CDI cannot alter the provider's response or instruct coding personnel to assign a diagnosis that the provider declined to establish.

The 2026 ACDIS/AHIMA Guidelines for Achieving a Compliant Query Practice supersede all previous versions and serve as the current foundational resource for query processes. The query process is intended to improve the accuracy, completeness, and integrity of documentation—not to secure a predetermined financial result.

A legitimate follow-up could occur if new laboratory values, operative findings, transfusion information, pathology, or other material information emerges after the original response and creates a materially different clarification question.

Professional CDI practice requires balancing clinical advocacy with provider autonomy, ethical conduct, and regulatory compliance.

CCDS Reference Topics: Provider query responses; ethical CDI practice; repeated queries; provider independence; compliance.

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Under the FY 2026 Hospital-Acquired Condition Reduction Program (HACRP), applicable subsection (d) hospitals in the worst-performing quartile based on the Total HAC Score receive a 1% payment reduction on applicable Medicare fee-for-service payments. CMS defines the worst-performing quartile as hospitals whose Total HAC Score is above the 75th percentile.

The FY 2026 program incorporates the CMS Patient Safety and Adverse Events Composite (PSI 90) plus five healthcare-associated infection measures: CLABSI, CAUTI, specified surgical-site infection, MRSA bacteremia, and C. difficile infection.

A single HAC does not automatically trigger the hospital-wide 1% HACRP reduction. Likewise, CMI is not the criterion used to determine HACRP penalties.

It is also important for CCDS candidates to distinguish the HAC Reduction Program from the separate DRA HAC/POA payment provision. CMS explicitly identifies them as distinct programs.

Accurate documentation and coding are important because quality measures rely on reliable clinical data, but CDI activity must remain focused on accurately representing the clinical record rather than manipulating quality metrics.

CCDS Reference Topics: HAC Reduction Program; PSI 90; HAI measures; quality payment; hospital performance.

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The query should be rewritten as a neutral, clinically supported clarification request. The original wording is noncompliant because it directs the physician toward a particular diagnosis and explicitly identifies its reimbursement consequence.

The current ACDIS/AHIMA 2026 Guidelines for Achieving a Compliant Query Practice, released in August 2026, supersede prior versions and emphasize that the query process exists to ensure the health record accurately reflects the patient's clinical status.

A compliant query could present relevant findings such as oxygen saturation, respiratory rate, blood-gas values, oxygen requirements, work of breathing, escalation to noninvasive or invasive ventilation, and treatment. It should then request clarification using clinically reasonable choices or another compliant format without highlighting which answer produces an MCC.

An oxygen saturation of 84% may be an important indicator, but a CDI specialist may not convert that finding independently into respiratory failure. The provider must evaluate the complete clinical picture.

Approval from a coding manager does not cure biased wording. Substituting “CC” for “MCC” likewise leaves the fundamental compliance problem intact.

CCDS Reference Topics: Query compliance; leading queries; respiratory failure; ethical CDI practice.

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Vascular dementia is the correct answer. CMS MS-DRG logic places qualifying vascular dementia diagnoses from category F01.- within MS-DRG 884, Organic Disturbances and Intellectual Disability. The FY 2026 CMS MS-DRG Definitions Manual specifically lists vascular dementia codes among the principal diagnoses assigned to MS-DRG 884.

MS-DRG assignment depends on the principal diagnosis code, major diagnostic category, procedures when applicable, and other grouper logic. Therefore, clinically related forms of dementia do not necessarily group to the same MS-DRG. Alzheimer's disease is classified primarily as a neurologic degenerative disorder and requires appropriate dementia manifestations where applicable. Alcohol-induced dementia is classified within substance-related mental and behavioral disorders, while Wernicke encephalopathy is associated with thiamine deficiency and follows different classification logic.

For CCDS practice, this question illustrates why documentation of dementia etiology and type matters. Simply documenting “dementia” can produce a less specific code and may affect MS-DRG assignment, risk adjustment, severity representation, and quality data.

The CDI specialist should seek clarification only when the clinical record supports a more specific dementia type.

CCDS Reference Topics: MS-DRG assignment; mental disorders; dementia specificity; IPPS reimbursement.

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Acute on chronic systolic heart failure is the intended answer. This scenario is adapted from an official ACDIS CCDS sample question, which uses dyspnea, edema, elevated BNP, reduced ejection fraction, and left-ventricular dysfunction to test appropriate heart-failure clarification.

The ejection fraction of 25% and documented left ventricular systolic dysfunction support a systolic phenotype. The patient's significant dyspnea and edema are consistent with acute decompensation superimposed on the established history of heart failure. Together, these findings create a legitimate opportunity to clarify type and acuity.

The CDI specialist must nevertheless avoid diagnosing acute-on-chronic systolic failure independently. The provider determines whether the findings represent acute decompensation, chronic disease, another heart-failure phenotype, or another explanation entirely.

Option A would require evidence supporting both systolic and diastolic dysfunction. Option B fails to capture the apparent acute decompensation. Option D conflicts with the documented systolic dysfunction and reduced EF.

This question illustrates a frequent CCDS theme: translating clinical indicators into a neutral clarification opportunity rather than assigning a diagnosis based solely on test results.

CCDS Reference Topics: Heart-failure acuity and type; ejection fraction; BNP; compliant query development.

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The CDI specialist should first review the final coded record together with the Coding Clinic guidance identified by the coder. This provides an objective basis for understanding why the final MS-DRG differs from the CDI working DRG.

A mismatch does not automatically indicate that either CDI or coding made an error. Working DRGs are provisional and may change after complete review of discharge documentation, operative reports, pathology, final diagnostic information, coding conventions, official guidelines, or authoritative Coding Clinic advice.

Reviewing the applicable guidance before contacting the coder promotes an informed and efficient reconciliation process. Once the specialist understands the coding rule, discussion with the coder may still be useful if ambiguity remains. Immediately escalating to the coding manager is unnecessary unless the issue cannot be resolved through normal collaboration. Forwarding the record without investigating the mismatch would defeat the purpose of a reconciliation process and could allow recurring education opportunities to remain unidentified.

Mismatch analysis is a valuable CDI quality metric because it can identify documentation gaps, coding-knowledge issues, changes in authoritative guidance, and opportunities to improve CDI/coding alignment.

CCDS Reference Topics: MS-DRG reconciliation; CDI/coder collaboration; Coding Clinic application; CDI program analysis.

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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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Prior-encounter information may provide valuable clinical context, but it should not automatically be imported as a current reportable diagnosis without considering whether the condition remains active and relevant to the present encounter.

Here, a prior diagnosis of chronic systolic heart failure, ongoing heart-failure therapy, and ambiguous current wording such as “history of CHF” create a reasonable opportunity to clarify the patient's current heart-failure status if that information is clinically relevant.

The CDI specialist should not independently carry forward the previous diagnosis or escalate it to acute heart failure. Conversely, rigidly ignoring reliable prior clinical information can prevent identification of legitimate documentation gaps.

The 2026 ACDIS/AHIMA query guidance specifically includes the role of prior encounters as part of its updated query-practice framework, while emphasizing compliant provider clarification and accurate representation of the current patient's clinical status.

A query should make clear which current clinical indicators support the need for clarification and should not imply that a previous diagnosis must automatically remain valid.

CCDS Reference Topics: Prior encounters; chronic conditions; heart failure; query practice; current-encounter documentation.

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The most clinically supported clarification is acute cerebral infarction. A transient ischemic attack is characterized by transient neurologic dysfunction without acute infarction. In this scenario, the patient's slurred speech has resolved, but the right-sided weakness persists, and CT demonstrates a new hypodense cerebral area. Together, those findings raise substantial concern for an established ischemic infarction rather than a completely transient event.

The CDI specialist should not independently convert the diagnosis of TIA to cerebral infarction. Instead, the persistent focal deficit and imaging findings establish an appropriate clinical basis for a provider query asking whether the final diagnosis is acute cerebral infarction, TIA, another neurologic condition, or clinically undetermined.

Acute encephalopathy generally produces global cerebral dysfunction rather than the focal unilateral weakness described here. Transient global amnesia predominantly affects memory formation and would not explain persistent unilateral motor deficits. Transient cerebral ischemia/TIA becomes less consistent once objective evidence of acute infarction and persistent neurologic impairment is present.

Accurate clarification is important because cerebral infarction and TIA differ substantially in coding, severity representation, quality reporting, and secondary-prevention planning.

CCDS Reference Topics: Neurologic clinical indicators; cerebral infarction versus TIA; diagnostic clarification; medical record specificity.

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The maximum payment reduction under the Hospital Readmissions Reduction Program is 3%. CMS expresses this through a payment adjustment factor ranging from 1.0, indicating no reduction, to 0.97, representing the maximum 3% reduction.

The HRRP links Medicare payment to excess readmission performance for specified clinical populations. CMS applies the resulting adjustment to applicable Medicare fee-for-service base operating DRG payments.

This program should not be confused with other Medicare hospital quality-payment initiatives. The HAC Reduction Program imposes a 1% reduction on hospitals in the worst-performing quartile, while Hospital Value-Based Purchasing uses a 2% reduction-and-redistribution mechanism.

CMS's FY 2026 IPPS final rule also finalized changes to HRRP methodology that begin with the FY 2027 program year, including incorporation of Medicare Advantage data into the six readmission measures and shortening the applicable performance period from three years to two.

For CDI, the central obligation remains ensuring that the clinical record accurately portrays patient severity, conditions treated, discharge circumstances, and comorbid disease burden.

CCDS Reference Topics: HRRP; readmission measures; quality reimbursement; payment adjustments; risk adjustment.

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The attending physician is the correct answer and this scenario is adapted from an official ACDIS CCDS sample item addressing conflicting medical-record documentation.

ICD-10-CM coding depends on provider documentation, but when clinically significant documentation conflicts within the record, the discrepancy must be clarified rather than resolved independently by the coder or CDI specialist. The FY 2026 Official Guidelines specifically state that when medical-record documentation conflicts, the patient's provider should be queried for clarification.

In the inpatient environment, the attending provider is generally responsible for synthesizing the patient's diagnoses and final clinical picture. A consultant's documentation may supply essential clinical information and may support code assignment when there is no conflict, but conflicting descriptions of heart-failure type or acuity should not simply be selected based on which diagnosis produces the higher-severity code.

The query should identify the conflicting statements objectively and request clarification of the clinically appropriate diagnosis. It should not suggest which diagnosis should be selected or mention reimbursement consequences.

This concept is central to CDI because unresolved contradictions can affect MS-DRG assignment, risk adjustment, severity measurement, quality reporting, and the clinical integrity of the record.

CCDS Reference Topics: Conflicting documentation; provider clarification; heart-failure specificity; medical-record integrity.

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Complete clinical documentation is the foundation of accurate MS-DRG assignment. The coding process translates provider documentation into ICD-10-CM and ICD-10-PCS codes, and those codes drive the MS-DRG grouper. If the record does not accurately capture the principal diagnosis, secondary diagnoses, acuity, etiologies, complications, procedures, and clinically relevant relationships, the resulting MS-DRG may not accurately represent the patient's hospitalization.

CMS explains that MS-DRG assignment depends on factors including diagnoses, procedures, complicating conditions, age, sex, and discharge status. Each resulting MS-DRG has a payment weight representing relative resource requirements.

POA documentation is important, particularly for HAC payment logic, but it is only one component of overall documentation completeness. Quality indicators and patient-satisfaction information serve other important organizational purposes but do not substitute for complete provider documentation when grouping the inpatient claim.

The role of CDI is therefore broader than capturing CCs or MCCs. CDI professionals work to ensure that the entire medical record provides a precise clinical description of the patient and services rendered, allowing coding, quality reporting, risk adjustment, utilization review, and reimbursement to be based on the same accurate clinical story.

CCDS Reference Topics: Documentation integrity; MS-DRG assignment; principal/secondary diagnoses; CDI fundamentals.

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Physician 4 has the most favorable risk-adjusted mortality rate, at 1.3, compared with Physician 1 at 1.5, Physician 2 at 2.0, and Physician 3 at 2.5. Although Physician 1 has fewer observed deaths and an observed mortality rate of 1.6%, public outcome comparisons commonly incorporate risk adjustment rather than relying solely on raw mortality. Risk adjustment attempts to account for differences in patient complexity, comorbid disease burden, demographic factors, and other characteristics that influence expected outcomes.

This is directly relevant to CDI because incomplete documentation of clinically significant comorbidities can understate patient severity and therefore adversely affect the expected mortality component of risk-adjusted performance calculations. Conversely, accurate documentation allows coded data to represent the actual severity and risk of the population being treated. Healthgrades specifically states that its mortality methodology adjusts for patient risk factors to permit more meaningful comparisons of clinical outcomes.

The CCDS content outline specifically requires knowledge of mortality indices, severity of illness/risk of mortality, physician performance, and the effect of documentation on publicly reported data.

CCDS Reference Topics: Impact of reportable diagnoses on quality of care; Healthcare facility CDI program analysis; mortality index and risk adjustment.

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For excisional debridement, documentation of the deepest tissue level actually removed is essential for accurate ICD-10-PCS procedure assignment. Relevant levels may include skin, subcutaneous tissue, fascia, muscle, or bone.

The presence of a deep wound does not establish that debridement reached the deepest anatomical layer visible in the wound. For example, a wound may extend to muscle while the physician removes only necrotic subcutaneous tissue. Coding must reflect the body part and tissue actually debrided rather than the overall depth of the wound.

Therefore, the CDI specialist should clarify what tissue was excised. Other procedural elements may already be supported by the operative documentation, including the excisional nature of the procedure.

The number of instruments or duration of anesthesia does not determine the applicable body-part value. Similarly, administrative details have no bearing on procedural specificity.

CDI specialists working with surgical records must understand the distinction between wound description and procedure performance. Accurate procedural documentation can affect ICD-10-PCS coding and ultimately MS-DRG assignment, particularly when an operating-room procedure influences grouper logic.

The CCDS competency framework includes medical-record review and coding/payment implications of inpatient procedures.

CCDS Reference Topics: Excisional debridement; ICD-10-PCS; tissue depth; operative documentation.

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CMS's Hospital-Acquired Condition payment framework specifically identifies Stage III and Stage IV pressure ulcers among the defined HAC categories when applicable conditions are not present on admission.

The distinction is important because not every pressure injury automatically triggers HAC payment treatment. Stage and POA status therefore require accurate documentation.

A hospital-acquired pressure ulcer remains reportable even when HAC payment provisions apply. CMS does not instruct hospitals to suppress or omit such conditions. Instead, defined HAC diagnoses that are not POA may lose the CC/MCC payment effect they otherwise would contribute to the MS-DRG, subject to applicable grouper rules.

The CDI specialist should ensure that wound location, laterality when relevant, stage, progression, and timing are accurately documented. Qualified wound-care nurse documentation may be used for pressure-ulcer staging under the ICD-10-CM non-provider documentation exception, while the diagnosis itself remains subject to provider-documentation requirements.

CDI professionals must also distinguish the HAC/POA MS-DRG payment provision from the separate HAC Reduction Program, which reduces applicable hospital payments by 1% for hospitals in the worst-performing quartile.

CCDS Reference Topics: HACs; pressure ulcers; POA; MS-DRG adjustment; wound documentation.

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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 Hospital Readmissions Reduction Program (HRRP) reduces payments to applicable hospitals with excess readmissions for specified conditions and procedures. CMS calculates a payment adjustment factor ranging from 1.0 to 0.97, meaning the maximum reduction is 3%.

The adjustment applies to applicable Medicare fee-for-service base operating DRG payments rather than solely to the readmission cases themselves.

This differs from the HAC Reduction Program, which applies a 1% reduction to hospitals in the worst-performing quartile based on defined hospital-acquired-condition measures. Hospital Value-Based Purchasing uses another methodology in which 2% of participating hospitals' base operating DRG payments funds value-based incentive payments.

For CDI professionals, readmission programs demonstrate how clinical documentation can influence more than individual MS-DRG reimbursement. Accurate documentation of comorbidities, principal diagnoses, complications, discharge circumstances, and disease severity contributes to reliable risk-adjusted data.

However, CDI intervention must remain focused on clinical accuracy rather than attempting to alter readmission metrics through unsupported diagnoses.

CCDS Reference Topics: HRRP; readmissions; quality reimbursement; IPPS; risk adjustment.

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The principal diagnosis is the condition established after study to be chiefly responsible for occasioning the patient's admission to the hospital for care. This is the UHDDS definition used in the ICD-10-CM Official Guidelines for inpatient principal-diagnosis selection.

“After study” is critical. The diagnosis initially suspected in the emergency department may change after diagnostic testing, consultation, treatment response, surgery, pathology, or other evaluation. The final principal diagnosis therefore may differ from the first diagnosis documented.

Relative weight does not determine principal diagnosis. A hospital cannot select a higher-paying condition merely because it produces a more favorable MS-DRG. Similarly, medication volume is not a principal-diagnosis criterion.

For CDI specialists, principal-diagnosis review requires understanding the circumstances surrounding admission, the diagnostic workup, final provider documentation, sequencing conventions, and any chapter-specific guidelines. When two conditions are documented and it is unclear which chiefly occasioned the admission, a provider query may be warranted.

The CCDS content outline specifically tests the principles and application of principal-diagnosis assignment.

CCDS Reference Topics: Principal diagnosis; UHDDS; inpatient sequencing; working MS-DRG.

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The key issue is whether the sepsis documented on hospital day 2 was present on admission (POA) or developed after admission. The admission already contains potentially relevant indicators—fever, pneumonia, hypotension, cultures, and IV antibiotic treatment—but a CDI specialist cannot independently determine from those indicators that sepsis was POA. Provider clarification is necessary.

This distinction directly affects principal-diagnosis sequencing. When sepsis and a localized infection such as pneumonia are both responsible for admission, the systemic infection is generally sequenced before the localized infection. Conversely, when the patient is admitted with pneumonia and sepsis develops only after admission, pneumonia is sequenced first.

The POA guidelines also emphasize that a diagnosis may not be recognized until days after admission and that delayed documentation does not automatically mean the condition was hospital-acquired. When timing is unclear, querying the provider is appropriate.

There is no evidence supporting aspiration pneumonia, so option B would introduce an unsupported concept. Options C and D prematurely determine principal diagnosis without resolving the timing of sepsis.

CCDS Reference Topics: Sepsis sequencing; POA assignment; principal diagnosis; compliant clarification of timing.

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Direct verbal communication can be an effective and appropriate CDI technique, particularly when the responsible physician is available and the issue can be clarified efficiently. The interaction must remain professional, clinically focused, and compliant with the organization's process for documenting or retaining verbal queries.

ACDIS specifically identifies collaboration with providers, verbal discussion, written queries, and resolution of missing, unclear, or conflicting documentation as core inpatient CDI responsibilities. The CCDS blueprint also tests situations in which personal or verbal communication may be preferable to written communication.

Option C is inappropriate because the CDI specialist should not direct the physician toward a diagnosis based on MS-DRG impact. The discussion should present the clinical issue neutrally and allow the physician to exercise independent clinical judgment.

There is also no rule requiring all queries to be electronic. Query format and retention should follow compliant organizational policies and current ACDIS/AHIMA standards. Waiting until final billing can unnecessarily delay resolution and undermine the advantages of concurrent CDI review.

Effective CDI communication balances clinical precision, efficiency, collegiality, and auditability.

CCDS Reference Topics: Verbal queries; physician communication; concurrent CDI; nonleading clarification; query documentation.

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The arterial blood gas primarily demonstrates respiratory acidosis. The pH is significantly acidemic at 7.24, while PaCO₂ is markedly elevated at 72 mmHg. Because carbon dioxide acts as an acid through the carbonic acid buffering system, CO₂ retention lowers blood pH.

The bicarbonate of 30 mEq/L is mildly elevated, suggesting some renal compensation, which may occur in patients with chronic CO₂ retention from COPD. However, the substantial acidemia indicates that compensation is insufficient and an acute component may be present.

In a COPD patient with acute respiratory distress, such findings can create an appropriate clinical basis for clarification of acute or acute-on-chronic hypercapnic respiratory failure when other supporting indicators are present, such as worsening work of breathing, altered mental status, escalating oxygen needs, BiPAP, or intubation.

The CDI specialist should not independently equate every abnormal ABG with respiratory failure. The provider determines the clinical diagnosis.

Respiratory alkalosis would involve reduced PaCO₂. Metabolic acidosis generally involves reduced bicarbonate as the primary disturbance, while metabolic alkalosis involves primary bicarbonate elevation with alkalemia.

CCDS Reference Topics: ABG interpretation; respiratory acidosis; hypercapnia; COPD; respiratory failure.

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The 38% post-discharge query rate represents the clearest workflow opportunity because a large proportion of clarification is occurring after the concurrent hospitalization period.

A 97% provider response rate reflects strong physician participation, while a 96% CDI/coder agreement rate indicates substantial alignment between concurrent CDI review and final coding. An 84% agreement rate is not inherently problematic because providers must remain free to disagree with a query based on their clinical judgment.

A high retrospective-query percentage can indicate that cases are being reviewed too late, that certain documentation opportunities are not recognized during hospitalization, that discharge documentation introduces unresolved diagnoses, or that staffing/workflow does not adequately prioritize cases before discharge.

A CDI manager should drill further into the metric by service line, query type, day of stay, weekday/weekend discharge, provider group, and reason for retrospective clarification. This analysis helps distinguish unavoidable retrospective queries from remediable process problems.

The objective is not to eliminate every post-discharge query. Some documentation issues become apparent only after final testing, pathology, procedures, or discharge summaries are completed.

CCDS Reference Topics: CDI program metrics; concurrent versus retrospective review; workflow analysis; performance improvement.

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The ICD-10 MS-DRG Definitions Manual contains the detailed grouper logic CMS uses for MS-DRG assignment. CMS states that the FY 2026 Definitions Manual files provide the complete documentation of ICD-10 MS-DRG grouper logic.

The manual organizes MS-DRGs by Major Diagnostic Category and includes the principal diagnoses, procedures, MCC/CC structure, exclusions, and other logic needed to understand how cases group.

As of September 2026, CMS identifies FY 2026 Version 43.1 as effective for discharges from April 1 through September 30, 2026. Version 44 begins October 1, 2026 for FY 2027.

The Physician Fee Schedule governs professional services and does not define inpatient MS-DRGs. HCAHPS concerns patient-experience measurement, while the National Correct Coding Initiative focuses primarily on coding edits designed to prevent inappropriate code combinations in other reimbursement contexts.

CDI specialists do not need to memorize every grouper pathway, but they should understand how principal diagnosis, secondary conditions, procedures, and CC/MCC classifications interact to determine the working and final MS-DRG.

CCDS Reference Topics: MS-DRG Definitions Manual; grouper logic; IPPS; current fiscal-year resources.

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An observed-to-expected mortality ratio is calculated by dividing observed deaths by expected deaths. Here, 125 divided by 100 equals 1.25. Therefore, observed deaths are 25% higher than the number predicted by the risk-adjustment model.

A ratio of 1.0 indicates observed mortality equals expected mortality. A value below 1.0 indicates fewer observed deaths than predicted, while a value above 1.0 indicates more observed deaths than predicted.

The CDI implication is important. Expected mortality is influenced by the patient's documented disease burden and other variables used by the applicable risk-adjustment methodology. If clinically significant conditions are underdocumented, the coded record may fail to represent the patient's actual severity, potentially reducing calculated expected mortality.

However, CDI should never seek diagnoses solely to improve a mortality ratio. Each diagnosis must be clinically supported and accurately documented. A high ratio can reflect multiple factors—including clinical outcomes, case mix, documentation, coding, data quality, or model characteristics—and should trigger multidisciplinary analysis rather than automatic querying.

ACDIS includes mortality and severity/risk adjustment within CCDS competency expectations.

CCDS Reference Topics: O/E mortality; risk adjustment; severity documentation; quality outcomes.

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The findings strongly support severe symptomatic hyponatremia. A serum sodium of 116 mEq/L represents marked reduction in extracellular sodium concentration, and the neurologic manifestations—confusion and seizures—indicate clinically significant cerebral effects.

Severe hyponatremia can produce cerebral edema because reduced extracellular osmolality promotes water movement into brain cells. Symptoms can range from nausea and headache to confusion, seizures, coma, and respiratory arrest in extreme cases.

Administration of hypertonic saline further demonstrates that clinicians are treating a significant sodium disturbance rather than an incidental laboratory abnormality. The rate of sodium correction requires careful monitoring because overly rapid correction, particularly in chronic hyponatremia, can cause osmotic demyelination.

Heart failure can contribute through impaired free-water excretion and neurohormonal activation, but CDI should not independently assign the etiology unless the provider documents it.

The specialist should present the sodium level, symptoms, treatment, and clinical course and request clarification if no corresponding diagnosis exists.

Hypernatremia represents elevated rather than decreased sodium. Hypercalcemia and respiratory alkalosis do not explain the sodium abnormality.

CCDS Reference Topics: Hyponatremia; electrolyte physiology; neurologic manifestations; clinical indicators; documentation specificity.

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ICD-10-CM permits a presumed causal relationship between diabetes mellitus and certain conditions indexed under “diabetes, with,” including chronic kidney disease. Therefore, when diabetes and CKD are both documented and the provider has not specifically indicated that they are unrelated, the diabetes-with-CKD combination code is assigned together with an additional code identifying the CKD stage.

For type 2 diabetes, diabetic CKD is classified to E11.22, while an N18.- code identifies the documented CKD stage. In this scenario, stage 4 CKD would be additionally represented by the appropriate stage-specific N18 code.

A query is not routinely necessary simply to obtain wording such as “diabetic CKD” when the classification itself establishes the presumed relationship. However, clarification would be appropriate if documentation explicitly states another unrelated etiology or contains contradictory information.

This distinction is important for CDI because excessive querying can create unnecessary provider burden. CDI specialists must understand which diagnostic relationships require explicit provider linkage and which are established through ICD-10-CM conventions.

The FY 2026 Official Guidelines remain applicable to discharges through September 30, 2026.

CCDS Reference Topics: Diabetes; CKD; presumed causal relationships; combination codes; coding conventions.

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When sepsis due to a localized infection is responsible for the admission, the systemic infection is generally sequenced first, followed by the localized infection. If acute organ dysfunction is documented as associated with the sepsis, severe sepsis coding additionally requires the appropriate R65.2- code and code(s) for the acute organ dysfunction.

The severe-sepsis code itself is not sequenced as principal diagnosis. The underlying systemic infection precedes it. In this case, the patient's AKI has specifically been linked to sepsis, supporting the severe-sepsis framework.

Pneumonia remains important because it identifies the localized source of infection, but it does not generally precede the systemic infection when sepsis is present on admission and is responsible for the hospitalization.

The CDI specialist should verify that the documentation clearly establishes the relationship between the acute organ dysfunction and sepsis. Organ dysfunction occurring in a patient with sepsis is not automatically attributable to sepsis when another cause is documented or clinically plausible.

The FY 2026 ICD-10-CM Official Guidelines govern these sequencing principles.

CCDS Reference Topics: Sepsis; severe sepsis; principal diagnosis; acute organ dysfunction; sequencing.

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The documented acute mental-status change associated with systemic infection creates a reasonable clarification opportunity for acute metabolic encephalopathy, assuming the complete clinical record supports that diagnosis.

Encephalopathy represents diffuse cerebral dysfunction arising from systemic, metabolic, toxic, hypoxic, infectious, or other causes. Acute confusion, impaired attention, fluctuating cognition, and absence of a focal lesion can support an encephalopathic process.

However, the CDI specialist cannot convert “altered mental status” into encephalopathy independently. The provider must determine whether the patient's presentation represents metabolic encephalopathy, delirium, medication effect, dementia, another neurologic condition, or simply a nonspecific symptom.

Chronic dementia does not fit the acute fluctuating pattern unless underlying dementia is separately documented. Cerebral infarction would generally require compatible focal neurologic findings and clinical or imaging evidence. Transient global amnesia typically presents with prominent acute memory disturbance rather than generalized encephalopathy.

A compliant query should include the mental-status findings, infectious process, relevant laboratory data, neurologic evaluation, treatment, and clinical course.

CCDS Reference Topics: Encephalopathy; altered mental status; infection; neurologic clinical indicators; diagnostic clarification.

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A line graph showing Risk of Mortality (ROM) and Severity of Illness (SOI) by month provides the strongest evidence of program impact over time because it displays longitudinal trends. Hospital leadership can readily determine whether documented patient complexity and risk profiles are increasing, decreasing, or remaining stable and can correlate those trends with CDI interventions.

The CCDS content outline specifically requires CDI specialists to analyze program trends, use SOI/ROM and other program-performance methodologies, create forecasting data, evaluate hospital performance, and track metrics over time. A line graph is particularly appropriate because time is the independent variable and changes from month to month are immediately visible.

An individual specialist's query rate primarily measures productivity or workflow rather than overall organizational impact. A pie graph of unanswered queries provides a snapshot of one process metric, not longitudinal program effectiveness. A presentation of program goals and objectives communicates strategy but does not demonstrate measurable results.

ROM and SOI also connect CDI work to quality and risk-adjustment outcomes, making them particularly meaningful to senior hospital administration.

CCDS Reference Topics: Healthcare facility CDI program analysis; trend analysis; SOI/ROM; physician and hospital performance.

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The findings strongly support a clarification opportunity for acute hypercapnic respiratory failure. The patient has a substantial acute rise in PaCO₂ above the documented baseline, respiratory acidemia with a pH of 7.27, hypoxemia, altered mental status, respiratory distress, and escalation to noninvasive ventilatory support.

In chronic CO₂ retention, renal compensation commonly increases serum bicarbonate and may allow a relatively preserved pH. A pronounced fall in pH in conjunction with a significant increase in PaCO₂ suggests an acute ventilatory deterioration. The need for BiPAP provides additional evidence of clinically significant respiratory compromise.

Option C is incorrect because the acidemia is driven primarily by elevated carbon dioxide, indicating respiratory rather than metabolic acidosis. Option A fails to capture the apparent acute deterioration from the patient's baseline. Option D is inconsistent with the physiologic abnormalities and treatment intensity.

The CDI specialist must still obtain provider documentation rather than independently diagnose respiratory failure. The CCDS examination specifically includes acute/chronic respiratory failure, COPD, ventilation support, and diagnostic-test interpretation among expected clinical competencies.

CCDS Reference Topics: Acute respiratory failure; hypercapnia; ABG interpretation; COPD; noninvasive ventilation.

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Provider query response rate is calculated by dividing the number of answered queries by the total number of queries requiring a response, then multiplying by 100.

360 ÷ 400 × 100 = 90%.

Therefore, the provider response rate is 90%.

Response rate measures whether clinicians engage with documentation clarification requests. It should be distinguished from agreement rate, which measures how often the provider's response supports the diagnosis or clarification being considered. A physician can respond appropriately while disagreeing with the proposed diagnostic possibilities, so a lower agreement rate does not necessarily indicate poor engagement.

A CDI manager should also evaluate response timeliness, service-line patterns, unanswered-query aging, escalation frequency, and whether responses result in complete documentation.

A response rate should not be artificially increased by pressuring providers to choose a particular answer. Current ACDIS/AHIMA guidance emphasizes a compliant clarification process that preserves independent provider judgment.

In mature CDI programs, metrics are best evaluated longitudinally rather than in isolation. Significant changes should be examined for workflow, staffing, education, electronic-query functionality, or physician-engagement factors.

CCDS Reference Topics: Query response rate; CDI metrics; provider engagement; program analysis; communication.

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The laboratory findings demonstrate reduction in all three major peripheral blood-cell lines: hemoglobin 7.8 indicates anemia, WBC 2,700 indicates leukopenia, and platelets 58 indicate thrombocytopenia. Collectively, this pattern is consistent with pancytopenia, making option C the most appropriate documentation clarification.

The National Cancer Institute defines pancytopenia as a lower-than-normal number of red blood cells, white blood cells, and platelets. Importantly, pancytopenia describes the hematologic state; it does not establish its underlying etiology. Myelodysplastic syndrome was only being ruled out in the scenario, so the CDI specialist should not infer it as the definitive cause.

Thrombocytopenia alone would capture only one component of the abnormal CBC and would fail to represent the simultaneous anemia and leukopenia. Myelophthisis implies marrow displacement or infiltration and cannot be inferred from these counts alone. Likewise, aplastic anemia is a specific bone-marrow failure diagnosis requiring provider determination and supporting diagnostic evaluation.

A compliant query can present pancytopenia as a clinically supported choice while allowing the provider to document another explanation.

CCDS Reference Topics: Hematology; clinical indicators; medical terminology; compliant query opportunity.

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When an admission is specifically for treatment of anemia associated with an adverse effect of chemotherapy or immunotherapy, and treatment is directed only at the anemia, the anemia diagnosis is sequenced first.

The FY 2026 ICD-10-CM Official Guidelines distinguish chemotherapy-related anemia from anemia caused directly by the malignancy. For chemotherapy-associated anemia, the anemia code is sequenced first, followed by the appropriate neoplasm code and the applicable adverse-effect code for the antineoplastic drug.

This differs significantly from anemia associated with the malignancy itself. If the patient is admitted solely to manage anemia caused by the malignancy, the malignancy is sequenced first, followed by the anemia-in-neoplastic-disease code.

The adverse-effect code is required to explain the medication-related cause, but it is not sequenced before the manifestation in this scenario because adverse-effect coding follows the nature of the adverse effect first.

For CDI specialists, accurate documentation of the cause of anemia—malignancy, chemotherapy, bleeding, chronic disease, nutritional deficiency, or another condition—is therefore essential because etiologic specificity can directly change sequencing.

CCDS Reference Topics: Chemotherapy adverse effects; anemia; neoplasm coding; principal diagnosis; sequencing.

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For POA reporting, “present on admission” refers to a condition present at the time the order for inpatient admission occurs. Conditions that develop during an outpatient encounter—including emergency-department, observation, or outpatient surgery care—before the inpatient admission order are generally considered POA when they are present at that inpatient admission point.

Therefore, the NSTEMI in this scenario is considered present on admission even though it developed after the patient physically arrived at the hospital.

This distinction is essential because hospital arrival and inpatient admission are not synonymous for POA purposes. A patient may spend hours in the ED or observation status before an inpatient order is entered.

The POA indicator applies to applicable principal and secondary diagnoses and is important to CMS's HAC payment provisions as well as quality analysis. A condition does not become hospital acquired merely because it arose somewhere on hospital premises before inpatient status began.

CDI specialists should clarify timing when the record does not establish whether a diagnosis existed before or after the inpatient admission order rather than relying solely on note timestamps or physical location.

The FY 2026 ICD-10-CM Official Guidelines contain the governing POA definitions and reporting rules.

CCDS Reference Topics: POA; emergency department; observation; timing of diagnosis; HAC payment logic.

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For an inpatient discharge, a diagnosis documented as “probable” may be coded as though the condition existed or was established when it remains documented as such at discharge.

The FY 2026 ICD-10-CM Official Guidelines provide a specific inpatient rule for uncertain diagnoses documented at the time of discharge. Terms such as probable, suspected, likely, questionable, possible, still to be ruled out, compatible with, and consistent with are coded as if the condition existed, because the diagnostic workup and treatment generally correspond to the suspected condition.

Therefore, aspiration pneumonia—not merely the respiratory symptoms—is the appropriate condition to code in this scenario.

This rule is specific to inpatient hospital coding and should not be generalized to outpatient encounters, where uncertain diagnoses are handled differently and symptoms or confirmed conditions are generally reported instead.

A query would still be appropriate if the documentation were contradictory, clinically ambiguous, or if multiple competing diagnoses remained without sufficient clarification. But the word “probable” itself does not create a mandatory inpatient query.

CCDS Reference Topics: Inpatient uncertain diagnoses; aspiration pneumonia; discharge documentation; Official Guidelines.

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An unanswered clinically significant query should be managed through the organization's defined escalation process. The process may involve CDI leadership, coding leadership, a physician advisor, department leadership, or other designated personnel, depending on organizational policy.

Neither CDI nor coding may independently supply the missing diagnosis because diagnostic conclusions remain the provider's responsibility. Removing an unresolved query simply to accelerate billing can undermine documentation integrity and may create compliance problems.

Escalation policies should be standardized rather than applied only when a particular diagnosis affects reimbursement. Policies commonly address expected response time, reminder intervals, responsible escalation personnel, high-priority queries, retrospective queries, and final-bill procedures.

The 2026 ACDIS/AHIMA Guidelines for Achieving a Compliant Query Practice supersede prior versions and serve as the current foundational guidance for organizations establishing compliant query policies and procedures.

A mature escalation process balances timely claim completion with respect for provider workload and independent clinical judgment. Its purpose is obtaining complete and accurate documentation, not forcing agreement with a CDI-generated diagnosis.

CCDS Reference Topics: Query escalation; organizational policy; unanswered queries; compliance; provider responsibility.

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ICD-10-CM Chapter 15 codes generally have sequencing priority over codes from other chapters when a condition complicates pregnancy, childbirth, or the puerperium.

Therefore, when pyelonephritis complicates pregnancy, the appropriate obstetric complication code is generally sequenced first, with additional code(s) used as instructed to identify the specific infection or organism.

This principle is important because ordinary principal-diagnosis logic can be modified by chapter-specific instructions. CDI specialists working with obstetric cases therefore must determine whether the pregnancy affects management and whether the condition is documented as complicating pregnancy.

The only major exception would be when the provider specifically determines that the pregnancy is incidental to the encounter and the applicable coding requirements for incidental pregnancy are met.

A symptom code does not generally supersede an established definitive diagnosis. Likewise, the fact that an infection could occur outside pregnancy does not negate Chapter 15 sequencing when it is complicating the pregnancy.

Correct gestational-age documentation is also important because an additional code may be required to identify the specific week of gestation.

CCDS Reference Topics: Obstetric coding; Chapter 15; sequencing priority; infection in pregnancy; principal diagnosis.

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