What does “code first” mean?
There are certain conditions that have instructional notes in the ICD-10-CM tabular/coding conventions that guide the coder in sequencing. This is especially true when the condition has a common manifestation or underlying conditions of a chronic disease. If there is a “code first” note in the tabular, the coder should follow this instruction and sequence the underlying etiology or chronic condition first followed by the manifestation as an additional diagnosis. There will be a “use additional code” note at the etiology/underlying condition.
Another thing to look for is in the code title of specific diagnoses “in diseases classified elsewhere”. This part of the title is telling the coder that this is a manifestation code and is never permitted to be sequenced as the PDX or first listed code. When coders see a code in brackets this indicates that this code should not be sequenced first.
Most Common Examples of Incorrect Sequencing:
- Patient presents for drainage of pleural effusion that is documented to be malignant secondary to lung cancer. The patient has thoracentesis and is discharged home. In this case, the PDX/first listed code will be the lung cancer followed by the code for the malignant pleural effusion. In the ICD-10-CM tabular, the coder will see notes under the Category J91.0 to code first the underlying neoplasm. Coders will see the same “code first” instruction when looking at malignant ascites.
- Patient present with anemia and is admitted for transfusion. The anemia is documented to be due to end stage renal disease (ESRD) after workup and consultation with hematology. The patient is discharged to follow up and to continue their outpatient hemodialysis (MWF). In this case, the PDX/first listed code will be the ESRD and not the anemia. Even though the anemia is the condition treated and focus of the admission there are instructional notes in ICD-10-CM tabular instructing the coder to “code first” the underlying chronic kidney disease.
- Patient is admitted with acute on chronic systolic congestive heart failure (CHF) and the diagnosis of hypertension. ICD-10-CM assumes a causal relationship, and this is coded as hypertensive heart disease with CHF and an additional code for the specific type of heart failure. In this case, the PDX of hypertensive heart disease with CHF (I11.0) is reported as the PDX followed by the code for the heart failure (I50.9) Under the Category I50 in the ICD-10-CM tabular there are instructional notes for the coder to “code first” if due to hypertension. There are multiple “code first” instructions under this category.
- Patient presents with confusion/altered mental status that is more than the normal for them. There is a history of Parkinson’s disease with dementia. Workup revealed that the patient’s Parkinson’s disease was progressing quickly, and their medications were altered. The patient was observed with 1:1 sitter without much improvement. It is recommended that the patient be admitted to a nursing home that focuses on dementia patients. In this case, the diagnosis code for the Parkinson’s disease (Dementia with Lewy bodies) is reported as the PDX followed by a code for the dementia in other diseases as an additional SDX. Coders will also see this in the ICD-10-CM Alphabetic Index, under dementia “with” Parkinson’s disease. The code for the Parkinson’s is listed along with the code for the dementia which is in brackets. Remember, codes in brackets are manifestation codes and not reported first.
- Patient presents with chest pain and has cardiac catheterization during their hospitalization. The cardiac catheterizations showed that the patient had multi-vessel coronary atherosclerosis of the native vessels with occlusion in one, as well as atherosclerosis due to calcified coronary and lipid rich plaque. In this case, the code for the atherosclerotic heart disease of the native coronary artery is sequenced as the PDX. The calcified coronary and the lipid rich plaque atherosclerosis would be reported as SDX due to the “code first” instructional note in ICD-10-CM.
Coders should always review and follow the chapter specific guidance and the ICD-10-CM tabular when coding to ensure that the appropriate PDX is selected. It is not always so black and white when the focus of the admission is towards the manifestation and not the condition causing it. This sequencing advice should only be followed when there is a coding guideline or instructional notes in ICD-10-CM. It will not always be the underlying condition reported as the PDX. The best examples of this that I can think of is anemia due to acute gastrointestinal (GI) bleeding and acute respiratory failure due to pneumonia/COPD exacerbation. In these cases, the PDX will depend on the focus of admission as there are no “code first” instructional notes to follow.
ICD-10-CM Official Guidelines for Coding and Reporting FY 2023 Pages: 10-15, and 52
ICD-10-CM Alphabetic Index and Tabular
ICD-10-CM/PCS, Coding Clinic, Fourth Quarter ICD-10 201 Pages: 87-88
ICD-10-CM/PCS, Coding Clinic, First Quarter ICD-10 2017 Pages: 43-44
ICD-10-CM/PCS, Coding Clinic, First Quarter ICD-10 2016 Pages: 39-40
ICD-10-CM/PCS, Coding Clinic, Fourth Quarter ICD-10 2016 Pages: 118-119
ICD-10-CM/PCS Coding Clinic, Fourth Quarter ICD-10 2016 Page: 141
ICD-9-CM Coding Clinic, Fourth Quarter 2011 Page: 107
ICD-9-CM Coding Clinic, Fourth Quarter 2008 Pages: 113-114
In need of coding support? We offer both inpatient coding support and outpatient coding support services. Partner with us to replace underperforming coding vendors, get coding backlogs caught up, staff for a FMLA/vacation gap, special projects, to assist in Single Path Coding, or for Total Outsource Coding Support.
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.
Subscribe to our Newsletter
to our Newsletter
Weekly medical coding tips and coding education delivered directly to your inbox.