When a patient is treated for dehydration caused by a malignancy, how should the diagnosis be sequenced?

In the case where a patient presents with dehydration specifically resulting from a malignancy, the correct sequencing of the diagnosis is to prioritize dehydration as the primary diagnosis. This is because dehydration is the immediate clinical condition that requires treatment and is the reason for the patient’s visit.

In ICD-10-CM coding, the primary diagnosis should reflect the reason for the encounter or the main issue being addressed. Although the malignancy is a significant underlying condition contributing to the dehydration, it is considered secondary in this context; the immediate problem of dehydration takes precedence.

When coding such situations, especially when a symptom or complication arises due to a larger condition (like a malignancy), the symptom or complication (dehydration in this instance) is sequenced first, followed by the underlying condition (malignancy). This approach communicates clearly to healthcare practitioners and payers what the patient was treated for during the visit.

Thus, the sequencing reflects the clinical significance of the conditions presented, aligning with best practices in medical coding.