(MS-DRG) Software - National Technical Information Service

DRG determinationTesting for illogical principaldiagnosisWhen a DRG has been matched, and the DRG number is 999, thecause is an illogical principal diagnosis. To indicate this, the returncode is changed to 6.Testing for multiple significanttraumaThe principal diagnosis is tested to see if it is a trauma code. If it is,processing continues to test for multiple significant trauma. Otherwise,no further trauma testing is done.To qualify as multiple significant trauma, two significant traumacodes from different body sites must be present. The diagnosis maskcontains special trauma indicators, with each body site trauma representedby a different flag.The mask of the first diagnosis (either principal or secondary) that isflagged as a significant trauma is saved. The mask of each subsequentdiagnosis that is also flagged is compared with the initial savedmask. If they are not the same, the record is flagged as a multiple significanttrauma episode. If they are the same, the next diagnosis istested until the multiple condition is satisfied or the diagnoses areexhausted.Finding codes that affectInitial DRG assignmentAfter the DRG has been determined, the grouper executor analyzesthe saved diagnosis and procedure masks, comparing them againstthe masks which were used to determine MDC and DRG. Codeswhich were necessary for the determination of the MDC/DRG areflagged with an “affect flag.”Final DRGIf no Hospital Acquired Conditions (HACs) are found on the record,then the initial DRG becomes the final DRG. Otherwise, the record isre-grouped demoting the HAC secondary diagnosis which may ormay not change the DRG assignment based on what DRG it was initiallyassigned to, and/or the presence of other codes that are CCs orMCCs.5.8 Medicare Severity DRG Software Installation Guide 10/10