Specificity in Getting Ms Drg Assignment Just Right

I wanted to write today about the Coding Clinic from the American Hospital Association for the third quarter of 2020 – specifically, pages 28-29, titled “Right middle cerebral artery infarction and bilateral carotid artery occlusion,” which has a question about coding the diagnosis. The provider documented that the right carotid artery stenotic plaque caused the right middle cerebral artery infarction.

The Coding Clinic response was to code the cerebral artery infarction due to right carotid artery stenosis/occlusion. The stenosis/occlusion of the left carotid artery should also be coded.

I found this advice very helpful when reviewing payor denials. If a coder assigns a diagnosis code for the infarction of the right middle artery (I63.511), in addition to the infarction of the right carotid artery (I63.231), then it is labeled inappropriate if the Medicare Severity Diagnosis-Related Group (MS-DRG) assigned is MS-DRG 64 (Intracranial hemorrhage or cerebral infarction with MCC). The second infarction code adds a Major Complication/Comorbid Condition (MCC). As I talked to other coders, I found that they were unaware of this Coding Clinic guidance.

The financial impact is not insignificant. Assuming a facility blended rate of $5,000, the reimbursement for MS-DRGs 64 through 66 is shown in the table below:

MS-DRG	Description	Relative Weight	Reimbursement
64	Intracranial hemorrhage or cerebral infarction w/MCC	2.003	$10,015.00
65	Intracranial hemorrhage or cerebral infarction w/CC	1.0164	$5,082.00
66	Intracranial hemorrhage or cerebral infarction w/o MCC/CC	0.6875	$3,437.50

The reimbursement swing is more than $6,500 for each case that is incorrectly coded.

My goal in talking about this Coding Clinic citation is to make you aware of its existence and for coders to be proactive and avoid assigning two stroke codes where only one is needed. It is important to also assign codes for the occlusions. Proactivity will avoid needless payor denials. I also think that there may be opportunities for physician queries and/or education. The physician should document, if possible, which occlusion/stenosis is responsible for the patient’s stroke.

Inpatient coding and MS-DRG optimization are like the tale of Goldilocks. It should be just right where the hospital gets the exact reimbursement that it deserves for treating the patient.