Pulmonary Embolism — Clinical Documentation Guide (2026)

This Clinical Documentation Guide (CDG) provides AAPC/AHIMA-credentialed coders and CDI specialists with comprehensive coding, clinical, and documentation guidance for pulmonary embolism (PE). Content reflects FY2026 ICD-10-CM guidelines (effective October 1, 2025 – September 30, 2026) and incorporates current clinical, risk-stratification, and MS-DRG reimbursement guidance. Use this guide to ensure accurate diagnosis code assignment, appropriate CDI query triggers, and defensible documentation for PE encounters across inpatient, outpatient, and observation settings.

🔍 1. Definition

Pulmonary embolism (PE) is the acute obstruction of one or more pulmonary arteries — or their branches — by a thrombus (most commonly), air, fat, amniotic fluid, tumor fragments, or foreign material. The obstruction increases pulmonary vascular resistance, impairs gas exchange, and, in severe cases, precipitates acute right ventricular (RV) failure. PE is classified along a spectrum from incidental subsegmental clots to massive, immediately life-threatening obstruction, as described by the 2023 AHA/ACC Scientific Statement on Venous Thromboembolism.

PE is the third most common acute cardiovascular condition after myocardial infarction and stroke, with an estimated 300,000–600,000 cases annually in the United States per CDC Blood Clots data. In-hospital mortality for massive PE can exceed 30%, and PE remains the most preventable cause of in-hospital death, according to NHLBI.

Severity stratification — massive (hemodynamic instability), submassive (RV dysfunction without shock), and low-risk — drives clinical management pathways including systemic thrombolysis, catheter-directed therapy, and anticoagulation alone. Accurate documentation of severity, laterality, and associated right heart findings directly impacts MS-DRG assignment and HCC risk adjustment.

Key Subtypes

• Acute PE with acute cor pulmonale: Right heart strain documented by echo, EKG, or clinical findings; captures the highest-severity codes (I26.0x) and maps to HCC 223.
• Saddle PE: Embolus straddling the bifurcation of the main pulmonary artery; associated with highest hemodynamic risk.
• Septic PE: Emboli from an infected thrombus or right-sided endocarditis; requires documentation of infectious source.
• Subsegmental PE (SSPE): Limited to subsegmental arteries; two new FY2025 codes (I26.93, I26.94) now capture single vs. multiple subsegmental PE — a major coding specificity advance.
• Chronic PE: Incompletely resolved acute PE leading to chronic thromboembolic pulmonary hypertension (CTEPH); coded separately as I27.82.
• Obstetric PE: Thromboembolism complicating pregnancy, delivery, or the puerperium; coded from O88.2x with an additional I26.9x code per obstetric sequencing rules.

🗂️ 2. Alternative Terminology

Coders and CDI specialists will encounter multiple terms in clinical documentation that map to the I26 category or related codes. The following table summarizes accepted and colloquial terminology:

🩺 3. Signs & Symptoms

PE presents across a spectrum from asymptomatic (incidentally found) to cardiovascular collapse. Classic and atypical presentations documented in the medical record support coding and CDI queries per NHLBI PE Symptoms:

Classic Presentation

• Sudden-onset dyspnea (most common symptom — up to 80% of cases)
• Pleuritic chest pain (sharp, worsened by inspiration)
• Hemoptysis (coughing up blood)
• Tachycardia (>100 bpm) and tachypnea
• Hypoxemia / low oxygen saturation
• Unilateral leg swelling, pain, erythema (concurrent DVT)

Massive PE (Hemodynamic Instability)

• Systolic BP <90 mmHg or drop >40 mmHg sustained ≥15 minutes
• Cardiogenic shock or cardiac arrest
• Syncope or near-syncope
• Acute right ventricular failure signs: JVD, RV heave, S3 or S4 gallop
• New right bundle branch block (RBBB) on EKG, S1Q3T3 pattern

Submassive PE (RV Dysfunction Without Shock)

• Echo: RV dilation, hypokinesis, septal flattening (D-sign), McConnell sign
• Elevated troponin I/T (myocardial injury from RV strain)
• Elevated BNP or NT-proBNP (RV pressure overload)
• Borderline or normal BP with tachycardia

Low-Risk / Incidental PE

• Subsegmental PE discovered incidentally on CT performed for another indication
• Minimal or absent symptoms; no hemodynamic compromise

Septic PE — Additional Findings

• Fever, chills, rigors; bacteremia or documented sepsis
• Multiple peripheral cavitary lung lesions on imaging
• Evidence of right-sided endocarditis, IV catheter infection, or septic thrombophlebitis

🧭 4. Differential Diagnosis

The following conditions share clinical features with PE and must be excluded or documented alongside PE for accurate coding:

📋 5. Clinical Indicators for Coders/CDI

The following clinical indicators support PE diagnosis coding and CDI query triggers. Presence of these elements without explicit provider documentation of PE should prompt a CDI query, not an assumption of the diagnosis:

🦴 6. Anatomy & Pathophysiology

Understanding PE pathophysiology supports accurate code selection, CDI queries, and audit defense.

Vascular Anatomy

The pulmonary arterial tree begins at the main pulmonary artery (arising from the right ventricle), which bifurcates at the carina into left and right main pulmonary arteries. Each further divides into lobar arteries (3 right, 2 left), segmental arteries (10 right, 8–9 left), and subsegmental arteries. A saddle embolus straddles the main pulmonary artery bifurcation, obstructing both sides simultaneously — the most hemodynamically devastating location per AHA/ACC 2023 VTE Statement.

Pathophysiology

PE results primarily from the Virchow triad: (1) venous stasis, (2) endothelial injury, and (3) hypercoagulability. DVT — most frequently in the proximal lower extremity veins (iliofemoral segment) — is the precursor to PE in approximately 70–80% of cases. The thrombus propagates proximally, breaks loose, and travels through the right heart into the pulmonary circulation.

Hemodynamic Consequences

• Increased pulmonary vascular resistance (PVR): Mechanical obstruction + hypoxia-mediated vasoconstriction raises afterload on the thin-walled RV.
• RV dilation and dysfunction: The RV, unaccustomed to high afterload, dilates; septal shift (leftward D-sign) reduces LV filling and cardiac output.
• Acute cor pulmonale: Acute RV pressure overload with RV failure — the clinical syndrome documented to assign I26.0x codes. Defined by the ACC as echocardiographic or clinical evidence of acute RV pressure overload.
• Decreased cardiac output → cardiogenic shock in massive PE.
• Impaired gas exchange: V/Q mismatch, alveolar dead space, reflex bronchoconstriction → hypoxemia, hypocapnia.

Subsegmental PE — Clinical Significance

Subsegmental PE (SSPE) involves clot limited to subsegmental arteries without proximal extension. Clinical significance is debated — many SSPE resolve without treatment, particularly in patients with low risk of DVT propagation. The NEJM PEITHO-3 trial data and current AHA guidelines suggest surveillance anticoagulation decisions in SSPE be individualized. The FY2025 addition of I26.93 and I26.94 allows coders to precisely document single vs. multiple SSPE — critical for accurate risk profiling and payer communication.

💊 7. Medication Impact / Treatment

Medications used in PE treatment have direct coding implications for complication tracking, drug codes (HCPCS), and Z-code assignment:

Anticoagulation (Primary Treatment)

• Unfractionated Heparin (UFH): IV bolus + continuous infusion; initial therapy for massive/submassive PE and when thrombolysis is being considered. Coded with J1655 (heparin lock flush — note: continuous infusion billed per unit). Z79.01 (long-term anticoagulant use) applicable for extended treatment.
• Low Molecular Weight Heparin (LMWH): Enoxaparin (J1650 per 10 mg), dalteparin (J1645 per 2,500 IU); preferred bridge or outpatient treatment. Report Z79.01 for long-term use.
• Fondaparinux: Factor Xa inhibitor; J1652 per 0.5 mg; alternative for HIT patients.
• Direct Oral Anticoagulants (DOACs): Apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), edoxaban (Savaysa) — first-line for most non-massive PE. Billed under Medicare Part D NDC codes, not outpatient HCPCS J-codes; document long-term use with Z79.01. See HCPCS section for Part B exceptions.
• Warfarin: INR-monitored oral anticoagulant; less common since DOAC advent; Z79.01.

Thrombolysis (Systemic)

• Alteplase (tPA): J2997 (per mg); systemic administration for massive PE with hemodynamic collapse; contraindicated in recent surgery/stroke. Monitor for bleeding complications — code any hemorrhagic adverse effect.
• Reteplase: J2998; alternative thrombolytic agent; similar monitoring requirements.

Catheter-Directed Therapy (CDT)

• Low-dose catheter-directed thrombolysis or ultrasound-assisted CDT (EkoSonic/EKOS); typically 10–24 mg tPA over 12–24 hours; coded with CPT 37187 or 37184–37188 based on procedure specifics. Document clinical rationale for CDT selection over systemic therapy.

Vasopressors / Resuscitative Agents

• Norepinephrine, vasopressin, dobutamine for cardiogenic shock complicating massive PE; document shock type and hemodynamic instability to support acute cor pulmonale coding (I26.0x).

Anticoagulation Reversal

• Andexanet alfa (Andexxa) for apixaban/rivaroxaban reversal; idarucizumab (Praxbind) for dabigatran reversal; protamine for heparin reversal — code adverse effects if applicable.

Preview ends here. The full guide continues with FY2026 ICD-10-CM code sets, CPT surgical coding, MS-DRG mapping, reimbursement guidance, CDI query templates, and an audit checklist — all available to CCO Members.

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