When a patient has multiple diagnoses, which should be listed first?

Happy New Year! 2018 brings new codes and guidelines for correct coding and billing. It is important to take time to review all documents with codes for correctness as many ICD/CPT/HCPCS codes were deleted or revised as well as new codes in all three code sets.

The topic for this installment of Coding Corner relates to sequencing diagnosis codes. When a patient has multiple diagnoses, which should be listed first?

If multiple medical problems were addressed and multiple diagnoses are needed to reflect the complexity of the care delivered, list the most important or serious condition the patient was treated for first.

For example, a patient may present with leg pain, but upon evaluation be found to have bilateral pedal edema secondary to new onset congestive heart failure requiring admission for further evaluation and treatment. Although the chief complaint may have been leg pain, the diagnosis of new onset congestive heart failure is more serious and would be listed as the first diagnosis. Whenever a patient requires admission to the hospital, the first diagnosis should clearly indicate the primary reason for admission.

A chronic condition requiring evaluation, treatment, or factors into your decision-making process when determining management options should also be listed as a diagnosis. These are often referred to as co-morbidities. For example, a patient may present with cellulitis, but is found to have uncontrolled diabetes or hypertension during their visit. In this case, it would be appropriate to list the uncontrolled diabetes and hypertension as a diagnosis.

ICD-10-CM Official Guidelines require some conditions and co-morbidities to be coded together. For example, a patient with chronic kidney disease (CKD) who is also hypertensive should always have hypertensive chronic kidney disease coded (I12.-), followed by the CKD stage (N18.-). A patient with diabetic foot ulcer would require multiple diagnosis codes describing the type of diabetes with foot ulcer (E1-.621), along with the laterality, specific foot location, and stage of the non-pressure foot ulcer (L97.-).

Additional Examples:

  • If a patient has multiple fractures, list the most severe fracture as the primary diagnosis.
  • If a patient has multiple burns of varying degrees or thickness, list the most severe burn first. Generally, 3rd degree burns should be listed before 2nd degree burns, which are listed before 1st degree/superficial burns. Additional codes should be assigned for the percentage of TBSA of the burn and the percentage involving third degree burns.