Clinical Foundations: Anatomy and Physiology, Pathophysiology, and Pharmacology
Clinical knowledge lets a CDI specialist recognize when documentation is incomplete or internally inconsistent. You need working familiarity across all body systems, but questions concentrate on conditions where documentation drives DRG assignment.
High-yield conditions
Heart failure (systolic, diastolic, combined; acute versus chronic); COPD with acute exacerbation versus asthma; pneumonia specified by organism versus unspecified; sepsis - sepsis must be documented, SIRS criteria alone do not establish it, and "urosepsis" means sepsis from a urinary source rather than a urinary tract infection; respiratory failure (acute versus chronic, hypoxia versus hypercapnia); acute kidney injury versus chronic kidney disease with stage; diabetes with manifestations (ketoacidosis, hypoglycemia, peripheral angiopathy, CKD); encephalopathy typed as metabolic, hepatic, or anoxic; malnutrition with clinical criteria documented; pressure ulcer stage, site, and laterality.
Pharmacology: know drug classes and how they support or contradict a diagnosis - IV antibiotics and cultures supporting sepsis, diuretics and vasodilators for heart failure, insulin infusions for DKA, anticoagulants, steroids, chemotherapy agents. The medication list is a legitimate clinical indicator for a query.
Traps: treating a lab value as a diagnosis; coding sepsis as principal when it arose after admission; accepting "history of" as current; naming a resolved condition as principal when another condition drove the stay.
Rule of thumb: ask whether a clinician actively treating this patient would agree the condition is present - and whether the record says so.
Worked example: creatinine doubles and urine output falls, but the note says "renal insufficiency." The criteria support acute kidney injury, yet you cannot assign it yourself; query with the criteria attached.