Clinical Coding
Conventions decide most questions
Coding items test both code lookup and the Official Guidelines for Coding and Reporting. Learn the conventions printed in the tabular list precisely.
Excludes1 means the two conditions cannot be reported together - 'not coded here.' Excludes2 means the excluded condition is not part of the code's meaning but may be coded additionally when documented. Code first identifies an underlying condition that must be sequenced first; code also signals an additional code that may be required but does not dictate sequencing; use additional code means a secondary code is needed to complete the picture. Laterality and 7th characters (A initial, D subsequent, S sequela) are frequent point-losers.
Sequencing: the inpatient principal diagnosis is the condition established after study to be chiefly responsible for the admission. The outpatient first-listed diagnosis is the reason for the visit, which may be a symptom. Never code inpatient diagnoses documented as 'probable,' 'suspected,' 'rule out,' or 'working diagnosis'; code to the highest degree of certainty - signs, symptoms, abnormal results. In outpatient settings, do not code uncertain diagnoses at all; report the symptom instead.
ICD-10-PCS codes have seven characters (section, body system, root operation, body part, approach, device, qualifier). Meaning is fixed by character position, not by a phrase lookup. CPT/HCPCS questions focus on E/M level selection, modifiers (-25, -59 and the X{E,S,P,U} modifiers), and NCCI bundling.
Worked example: Inpatient note says 'rule out pneumonia' with cough and fever; chest x-ray is negative. Do not assign pneumonia; assign the signs/symptoms (e.g., cough, fever) if no confirmed diagnosis explains them. If the discharge summary confirms pneumonia, code pneumonia.
Traps: treating Excludes2 as a prohibition; sequencing a symptom when a definitive diagnosis exists; coding a sequela as a current injury; assuming a modifier repairs documentation that does not support it.