Chronic Subsegmental Pulmonary Emboli-One Code or Two?

Pulmonary emboli are blood clots within the arteries of the lungs. These blood clots prevent the flow of blood to the lungs which in turn prevents oxygen from reaching the lung tissue which lowers the oxygen levels in the lungs and increasing the blood pressure in the pulmonary arteries. The longer the clot is blocking the oxygen the more damage can occur in the other organs. An embolism is not the same as a thrombosis. A thrombosis is formed in the vein and stays in the same site until possibly resolved with medication or treatment. If a clot or piece of clot breaks free from the wall of the vein and travels to another site it is an embolus. An emboli moves around through the blood vessels until it reaches a small vessel that it cannot pass through, which causes the blockage.

There are up to 600,000 cases a year in the USA.

Causes for Pulmonary Emboli:

Blood clots that travel from another site of the body into the lungs. These are mostly from the deeper veins in the legs, but rarely can travel from another body part. Long periods of inactivity or immobility are common causes. Other medical conditions, surgery, trauma, and hypercoagulable states (both inherited and acquired) are also causes.

Symptoms/warning signs of Pulmonary Emboli:

  • Sudden shortness of breath
  • Worsening chronic shortness of breath
  • Chest pain (sharp/stabbing and usually worse when taking in a breath)
  • Coughing (including bloody sputum)
  • Cyanosis (clammy or discolored skin tone)
  • Sweating/fever
  • Rapid heartbeat or irregular heartbeat
  • Pain in the site of the culprit thrombosis (usually in the leg)
  • In about 25% of patients, sudden death is the first symptom of pulmonary emboli

Treatment of Pulmonary Emboli:

Pulmonary emboli require emergent medical care/treatment. These emboli typically resolve in a matter of days to weeks. The goal of treatment is to stop the clot from getting larger, preventing new clots, and resolving the existing clot. Anticoagulants are most often used to help prevent further clotting. Thrombolytics are also considered for treatment of thrombus/emboli. Patients with a high risk of bleeding may receive an inferior vena cava filter or have a thrombectomy performed.

Coding Concerns and Facts:

With the creation and implementation of ICD-10-CM, multiple codes are available to describe the type of pulmonary emboli that occur. At times, it will require more than one code to fully describe the patient’s condition. By coders reporting all allowable codes to show the patient’s condition, this will enable reporting of clinical differentiation as well as being beneficial for quality measures, research, and evaluation of efficacy of any given treatments.

The most recent coding advice given was discussing what to code when a patient is diagnosed with chronic bilateral subsegmental pulmonary emboli. The question from the coder was how to report this since in the Alphabetic Index there are separate subentries at the same indention level to describe chronic as well as multiple segmental. The response was to code both since this would fully describe the patient’s condition and there was an Excludes 2 note at category I26 indicating both codes were allowed when appropriate.


pulmonary (acute) (artery) (vein)   I26.99
      • with acute cor pulmonale   I26.09
      • chronic   I27.82
      • following
        • abortion- see Abortion by type complicated by embolism
          ectopic or molar pregnancy   O08.2
      • healed or old   Z86.711
      • in pregnancy, childbirth or puerperium- see Embolism, obstetric
      • multiple subsegmental without acute cor pulmonale   I26.94
      • personal history of   Z86.711
      • saddle   I26.92
        • with acute cor pulmonale   I26.02
      •  septic   I26.90
        • with acute cor pulmonale   I26.01
      •  single subsegmental without acute cor pulmonale   I26.93
      • subsegmental NOS   I26.93


With COVID-19, we are seeing more and more pulmonary embolisms associated with the diagnosis. When this is documented, the coder should determine, based on the physician documentation, if the COVID infection is current/active or a previous infection. That will determine the PDX in these cases.

  • If the COVID infection is current the code U07.1, COVID-19, is sequenced first followed by the code for the pulmonary embolism manifestation I26.99, Other pulmonary embolism without acute cor pulmonale.
  • If the COVID infection is no longer present and only a previous condition, the coder would assign the PDX as I26.99, Other pulmonary embolism without acute cor pulmonale, followed by B94.8, Sequelae of other specified infectious and parasitic diseases or as of discharges of October 1, 2021, U09.9, Post COVID-19 condition, unspecified.


For coding, it is all about clear, consistent, and concise documentation to arrive at the appropriate code(s). Following the instructional notes within ICD-10-CM is a must.  Sequencing of the codes will depend on circumstances of admission and official coding guidelines for selection of the principal diagnosis.


ICD-10-CM/PCS Coding Clinic,  Fourth Quarter 2019 Pages: 6-7
ICD-10-CM/PCS Coding Clinic, Second Quarter 2021 Pages: 9-10
ICD-10-CM/PCS Coding Clinic, Third Quarter 2020 Page2: 10-11


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The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.

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