Q&A: Diagnostic lumbar puncture versus mechanical ventilation as principal procedure

Q: We recently had a patient admitted with severe acute meningitis causing respiratory decompensation. A diagnostic lumbar puncture and mechanical ventilation were both performed during the inpatient stay. Which of the two procedures would be the principal procedure, diagnostic lumbar puncture or mechanical ventilation? 

A: Selection of the principal procedure can be confusing, so let’s start from the beginning with the selection of the principal medical diagnosis, first. In this scenario, the patient is admitted with severe acute meningitis with a secondary of diagnosis of respiratory decompensation. This patient had two interventions performed, so you need to decide whether these interventions were performed for the principal diagnosis or a secondary diagnosis. Then, you need to determine whether they were done for definitive treatment or diagnostic/exploratory purposes of either the principal diagnosis or for a secondary diagnosis. 

With these two interventions, I can tell you that the lumbar puncture was performed as a diagnostic test for the severe acute meningitis; there wasn’t an intervention or procedure done for definitive treatment. The intervention of the mechanical ventilation was for the respiratory decompensation.

Now, we follow the Official Guidelines for Coding and Reporting which tell us that if you have any interventions/procedures performed for the principal medical diagnosis, you need to evaluate their purpose (definitive treatment versus diagnostic/exploratory). Any interventions performed for definitive treatment would supersede any procedure/intervention for diagnostics/exploratory purpose. If you have no intervention/procedure done for definitive treatment of your principal medical diagnosis, then you would code for the intervention/procedure done for the diagnostic/exploratory purpose as your principal procedure (like in this scenario).

If you have no intervention done for any reason for your principal medical diagnosis, then turn to any interventions/procedures performed for a secondary diagnosis and follow the same process of elimination, again with definitive treatment sequenced before exploratory/diagnostic purposes.

So, based on the information provided, I know that the lumbar puncture will be the principal procedure because it was done for the principal medical diagnosis and the fact that there was no procedure/intervention done for definitive treatment of the meningitis.

Now when using an encoder, all this work is done behind the scenes using the encoder logic. When doing it manually, however, a CDI specialist would follow the process I outlined above. When a patient has more than one procedure done for definitive treatment of the principal medical diagnosis, the CDI specialist would turn to the surgical hierarchy table located in the DRG Expert which would base the selection of the principal procedure on cost and resources used to determine the principal procedure.

Editor’s Note: Sharme Brodie, RN, CCDS, CCDS-O, CDI education specialist and CDI Boot Camp instructor for HCPro in Middleton, Massachusetts, answered this question. For information, contact her at sbrodie@hcpro.com. For information regarding CDI Boot Camps, click here. This article was originally published in July 2019 and was updated according to the newest coding and documentation guidelines.