Health Information Management

Q&A: Definition of ’marrying’ DRGs

CDI Strategies, August 4, 2011

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Q: I am having trouble grasping the concept of “marrying” DRGs. Can you explain what this means and how it affects CDI practice? 

A:The concept of “marrying” DRGs is based on the coded combination of a principal diagnosis from a particular body major diagnostic category (MDC)/system/family/grouping, and a procedure categorized from the same MDC/body system/family/grouping. The procedure is typically related to principal diagnosis, but not always. Sometimes it just so happens that the principal diagnosis and a secondary (or subsequent) diagnosis come from the same MDC and the procedure (performed to treat that secondary diagnosis) “marries” that way.

Valid (or reimbursable) OR procedures always change your original medical DRG to a finalsurgical DRG.   For example: on your first and second record reviews you identify the medical principal diagnosis and secondary medical diagnoses. On your third review you note that the patient has now undergone a surgical procedure. Once the patient has a valid OR procedure, your medical DRG is superseded (or overridden) by the surgical DRG. If the procedure is indexed or located in the same MDC as your medical starting DRG, we call that a “marriage” and the final surgical DRG is in the same MDC. 
In these situations, the so-called “marriage” is actually based on the assigned codes. Here are a few examples of DRG marriages to help illustrate this situation:
 For example, a patient’s principal diagnosis is documented as pulmonary embolism, and the principal procedure is a partial lobectomy. Although you’d probably never see this procedure performed due to the pulmonary embolism, both the partial lobectomy and the pulmonary embolism are categorized in MDC 4, Respiratory; so they “marry.”
Follow these steps when you’re working within the DRG Expert to determine if a “marriage” exists:
  1.  Identify the principal diagnosis and then look to see which MDC (this diagnosis groups into.  Take gastrointestinal bleed (MDC 6) as an example. MDC 6 would be your starting chapter in the DRG Expert. Remember this is just your starting point.
  2. Next, let’s say that the patient goes to surgery and physician documents that the patient has a hernia repair. At this point, ask yourself if the surgical procedure is also found in the same MDC as the principal diagnosis. So, if gastrointestinal bleed is located in MDC 6, ask yourself whether hernia repair is also located in MDC 6. Remember, however, that some procedures are found in multiple MDCs. You want to know if this procedure is in your starting MDC.
  3. Now, look up the code for the surgical procedure (or ask a coder) and then look at your surgical DRG options in MDC 6.  If the procedure is in one of the surgical DRGs in MDC 6 (and in this example, it is), you have a “marriage.” Even though this procedure was not performed to treat the gastrointestinal bleed, both the principal diagnosis and the procedure are in MDC 6, so it “marries.”
  4. If the procedure is not listed under one of your surgical DRG choices in MDC 6, then you have an “unrelated surgical procedure” and the final surgical DRG will then come from what I like to think of as the “shopping mall,” or the section after MDC 25 – “DRGs Associated with all MDCs.”

Editor’s Note: Lynne Spryszak, RN, CPC-A, CCDS, CDI education director for HCPro, Inc., in Danvers, MA, answered this question. Contact her at We welcome your CDI-related questions. E-mail them to


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