Coding Borderline Diagnoses

A recent Coding Clinic (Q 1 2012) answered the following question:


Coders are confused as to the correct coding of “borderline” diagnosis. The advice published in Coding Clinic, First Quarter 2011, pages 9-10, appears to be contradictory. The advice instructs coders to assign code 416.8, Other chronic pulmonary heart diseases, for borderline pulmonary hypertension as if it were confirmed; however, a diagnosis of borderline diabetes without further confirmation of the disease is assigned to code 790.20, Abnormal glucose.
Should code 793.2, Nonspecific (Abnormal) findings on radiological and other examination of body structure, Other intrathoracic organ, be assigned for a diagnosis of “borderline pulmonary hypertension” or should all borderline diagnoses require clarification from the attending physician so that the appropriate code may be reported?

Coding Clinic's Advice:

"Borderline diagnoses" are coded as confirmed, unless the classification provides a specific entry (e.g., borderline diabetes). If a borderline condition has a specific index entry in ICD-9-CM, it should be coded as such.

They went on to indicate that  borderline conditions are not uncertain diagnoses, and no distinction is made between the care setting (inpatient versus outpatient). 


However, when documentation is unclear regarding a borderline condition, coders should query for clarification.