A rerun to confirm the first result

Read an original fictional chart, identify the supported facts, and explain your coding workflow.

Chart gym · Original fictional record

Service date: 2026-09-09 · Outpatient laboratory; Medicare reporting relationship

Use your code books and write your reasoning before opening the walkthrough. This exercise contains no real patient information.

Clinical order

Fictional adult has an authenticated order for a serum potassium measurement during an outpatient evaluation. The laboratory receives one acceptable specimen. This exercise reviews repeat units, not the diagnosis supporting the original test or its final exact entry.

Laboratory record

The initial instrument result is unexpectedly high. The technologist immediately reruns the same specimen under the laboratory’s confirmation procedure. No new specimen is collected, and no treatment occurs between the two instrument runs. The second run verifies the original measurement.

Final report

The laboratory releases one reportable potassium result. The internal worksheet preserves both instrument readings and identifies the second as verification. The treating practitioner did not request a later treatment-response result during this sequence.

Draft claim

The draft contains two units and modifier 91 because the instrument ran twice. Compare the laboratory’s internal quality work with the need for multiple clinical results. Do not infer a second independently necessary test from two timestamps.

Your coding worksheet

Identify why the test was rerun.
Distinguish instrument readings from reportable clinical results.
Evaluate modifier 91 and the second unit.
State what a different clinical-repeat record would need.

In your notebook, record the supported facts, your index route, the instructions you checked, and any missing detail that limits your answer.

Compare with the worked explanation

The second run confirms the initial result.
One reportable result is needed and released; the internal readings do not independently define units.
NCCI includes confirmation work and does not support the extra unit.
A necessary later result during treatment requires its own supporting order, clinical purpose and applicable repeat-test review.

Reference sections: A,C

Practice the linked chart questions