Pathology & Laboratory
The pathology and laboratory section covers panels, individual tests, surgical pathology, and molecular/microbiology studies. The exam tends to test the rules that govern how these codes combine — the all-or-nothing nature of panels, the professional/technical split in surgical pathology, and the modifiers used for repeat and serial testing.
Panels are all-or-nothing
Organ- or disease-oriented panels (such as the basic metabolic panel, comprehensive metabolic panel, or hepatic function panel) are defined by a fixed list of component tests. The panel code may be reported ONLY when every listed component is performed. If only some components are done, you report the individual tests instead — and you may not report a panel plus its own components, which would be double-counting. Coders should also avoid combining panels in a way that duplicates shared components.
Surgical pathology levels and repeat testing
Surgical pathology codes are leveled by specimen type and the complexity of examination required, and — like radiology — they can split into technical (accessioning, processing, slide preparation) and professional (the pathologist's microscopic interpretation and diagnostic report, modifier -26) components. For clinical lab tests intentionally repeated on the same day to obtain serial results, append modifier -91; it is distinct from -76 (repeat procedure by the same physician), which is not used for laboratory work, and from re-runs of a failed specimen, which are not separately billable.