Combination codes are used to classify two diagnoses, a diagnosis with a manifestation, or a diagnosis with an associated complication. A complication is a condition that arises during the hospital stay that prolongs the length of stay by at least one day in approximately 75 percent of cases1. Complications may affect payment and severity of illness and risk of mortality classifications. Examples of combination codes that include a diagnosis with an associated complication are:
I50.23 Acute on chronic systolic (congestive) heart failure
K57.21 Diverticulitis of large intestine with perforation and abscess with bleeding
O34.211 Maternal care for incompetent cervix with cerclage, first trimester
A diagnosis that is an integral part of a disease process is not a valid option for combination codes, because it does not represent a separate or additional condition that needs to be coded. For example, chest pain is an integral part of acute myocardial infarction and does not require a separate code.
A diagnosis with an associated procedure is not a valid option for combination codes, because procedures are coded separately from diagnoses using ICD-10-PCS codes. For example, appendicitis with appendectomy is not a combination code, but rather two codes: one for the diagnosis (K35.80 Acute appendicitis without perforation or gangrene) and one for the procedure (0DTJ4ZZ Resection of appendix, percutaneous endoscopic approach).
A diagnosis with a sequelae or late effect is not a valid option for combination codes, because sequelae or late effects are coded separately from the original condition using the appropriate code from category B90-B94 Sequelae of infectious and parasitic diseases or category I69 Sequelae of cerebrovascular disease, followed by the code for the specific condition2. For example, hemiplegia following cerebral infarction is not a combination code, but rather two codes: one for the sequelae (I69.351 Hemiplegia and hemiparesis following cerebral infarction affecting right dominant side) and one for the original condition (I63.9 Cerebral infarction, unspecified).
References:
CDIP Exam Preparation Guide, 2021 Edition. AHIMA Press. ISBN: 9781584268530
ICD-10-CM Official Guidelines for Coding and Reporting FY 2022
Identifying ICD-10 Combination Codes - Outsource Strategies International
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