Q&A: Identifying the MS-DRG for unreleated surgical procedures

Q: Could you please explain unrelated surgical procedure DRGs? For example, a patient with a principal diagnosis of pneumonia whose surgical procedure transurethral resection of the prostate (TURP), MS-DRG 168. Also can you explain how we can differentiate between extensive operating room (OR) procedure and non-extensive OR procedure.

A: Many CDI specialists with a clinical background are what I like to call, encoder dependent. What I mean by that is we’ve been trained to “code” using an encoder and create our working MS-DRGs based on “grouper” software. It is often helpful to understand how to manually assign a MS-DRG. The basics steps for assigning a MS-DRG are as follows:

1. Identify all the applicable diagnoses in the health record
2. Identify the principal diagnosis (the condition after study to be chiefly responsible for occasioning the admission)
3. Determine its associated ICD code (we currently use ICD-9-CM, but we’ll eventually use ICD-10-CM)
4. Identify the base/medical DRG noting its Major Diagnostic Category/body system
5. Identify any/all procedures

This is where it can get a little tricky. The UHDDS (Uniform Hospital Discharge Data set) defines the principal procedure as

• One that was performed for definitive treatment, rather than one performed for diagnostic or exploratory purposes, or was necessary to take care of a complication
• If there appear to be two procedures that are principal, then the one most related to the principal diagnosis should be selected as the principal procedure

If there was a procedure performed take the following steps:

1. Determine the associated procedure codes (currently based on ICD-9-CM Vol. 3 codes and soon to be ICD-10-PCS) and determine if the procedure code associated with the principal procedure as listed in the DRG Expert?
2. If the code isn’t in the DRG Expert index of procedures, it is for one of two reasons: Either it is not a “reimbursable” procedure (i.e., one that will affect the MS-DRG assignment) or is it a major OR procedure
3. If there isn’t a procedure or it doesn’t impact DRG assignment, does the medical DRG allow for movement i.e., can patients be put into different groups based on the presence or absence of a complicating condition (CC) or major complicating condition (MCC)
4. If so, check to see if any of the remaining diagnoses, which are now considered “secondary diagnoses” are CCs or MCCs
5. Finalize the working DRG
6. If the procedure code is in the same MDC/body system as the principal diagnosis assign the new surgical MS-DRG (this is the most common scenario and is often referred to as a “match”)
7. If the procedure code is not in the same MDC/body system a different process is used to assign the surgical MS-DRG

The MS-DRG system is based on the assumption that if there is a “reimbursable” medical intervention/procedure that the case/claim will remain in the same body system (MDC) as the principal diagnosis will apply. However, there are occasions when the principal procedure is not related to the principal diagnoses because it is associated with a different MDC/body system as in the example you describe, which will require you to take some additional steps, including:

1. Turn to the start of “DRGs Associated with All MDCs.”
2. Scan the procedure codes listed under DRG 984 Prostatic O.R. Procedure Unrelated to PDX to try to locate the applicable procedure code.  These are codes that range from 60.0 to 60.99 within ICD-9-CM Vol. 3. If the applicable code is found under DRG 984 then the case will fall within a DRG referred to as a “triplet” where either a CC or a MCC can “move” the DRG. Check the remaining diagnoses codes to see if any are classified as a CC or MCC and finalize the working DRG based on the value of the applicable secondary diagnoses resulting in a final DRG between 986 and 984

Your example of a principal diagnosis of pneumonia (respiratory system MDC) with a procedure of a TURP will fall into one of these DRGs because the TURP is not a procedure located within the respiratory MDC/body system, but is classified as a prostate procedure and found under DRG 984. Your final MS-DRG assignment will depend on the presence or absence of secondary diagnose classified as a CC or MCC.

If the procedure code is not found under DRG 984, scan the procedure codes listed under DRG 987 Nonextensive O.R. Procedure Unrelated to PDX to try to locate the applicable procedure code. These codes span several pages within the DRG Expert. If the applicable code is found under DRG 987 then the case will fall within a DRG referred to as a “triplet” where either a CC or a MCC can “move” the DRG. Check the remaining diagnoses codes to see if any are classified as a CC or MCC and finalize the working DRG based on the value of the applicable secondary diagnoses resulting in a final DRG between 987 and 989.

If the procedure code is not found under DRG 984 or DRG 987 and it was not associated with a page when referencing a procedure index or if it was found, it was in a different MDC/body system than the PDX then the assumption is the case/claim belongs in DRGs 981-983. This final step requires a leap of faith since it is based on a process of elimination where this is the “last resort” for DRG assignment. These DRGs are heavily scrutinized by external auditors as assignment within these DRGs can erroneously inflate reimbursement if the case was improperly assigned. As above, this is a DRG is a “triplet” where either a CC or a MCC can “move” the DRG. So check the remaining diagnoses codes to see if any are classified as a CC or MCC and finalize the working DRG based on the value of the applicable secondary diagnoses.

Editor’s Note: Cheryl Ericson, MS, RN, CCDS, CDIP, answered this question. At the time of this article's original release, she was the CDI Education Director for HCPro Inc.