ICD-10 & Medical Coding Basics Cheat Sheet

A printable reference covering ICD-10-CM, CPT, HCPCS, code structure, coding accuracy, and basic medical billing concepts for grades 11-12.

Download PNG

Related Infographics

ICD-10 and medical coding basics explain how health conditions, procedures, and medical supplies are translated into standardized codes. Students need this cheat sheet to understand how medical records connect to billing, insurance claims, public health data, and patient care documentation. It is especially useful for learning the difference between diagnosis codes and procedure codes. Clear coding helps health care teams communicate accurately and reduces claim errors.

Key Facts

ICD-10-CM codes report diagnoses, symptoms, and medical conditions, such as E11.9 for type 2 diabetes mellitus without complications.
CPT codes report medical, surgical, and diagnostic procedures, such as 99213 for an established patient office visit.
HCPCS Level II codes report products, supplies, equipment, and some services not fully covered by CPT, such as E0114 for crutches.
ICD-10-CM codes usually begin with a letter followed by numbers, and they can contain 3 to 7 characters.
The first-listed diagnosis is the condition chiefly responsible for the patient encounter in many outpatient coding situations.
Coding should be based on provider documentation, not on assumptions, memory, or what seems likely.
Specificity matters because a more detailed code, such as one identifying laterality or severity, is usually more accurate than an unspecified code.
A claim may be denied if the diagnosis code does not support the medical necessity of the procedure or service code.

Vocabulary

ICD-10-CM: A diagnosis coding system used in the United States to classify diseases, injuries, symptoms, and reasons for health care encounters.
CPT: A procedure coding system used to report medical services and procedures performed by health care providers.
HCPCS Level II: A coding system used for medical supplies, durable medical equipment, medications, and certain services not fully described by CPT.
Diagnosis Code: A code that identifies the patient’s condition, illness, injury, symptom, or reason for receiving care.
Procedure Code: A code that identifies a service, test, treatment, or procedure provided to a patient.
Medical Necessity: The requirement that a service or procedure is reasonable and needed for the diagnosis or treatment of a patient’s condition.

Common Mistakes to Avoid

Confusing ICD-10-CM with CPT is wrong because diagnosis codes explain why care was needed, while CPT codes explain what service was performed.
Choosing an unspecified code too quickly is wrong because the medical record may contain details such as location, severity, or laterality that support a more accurate code.
Coding from a suspected diagnosis as if it were confirmed is wrong because outpatient coding usually requires signs, symptoms, or confirmed conditions based on provider documentation.
Ignoring laterality is wrong because many ICD-10-CM codes distinguish right, left, bilateral, or unspecified body sides.
Using a procedure code without a supporting diagnosis is wrong because payers often require the diagnosis to show medical necessity for the service.

Practice Questions

1 A patient is diagnosed with uncomplicated type 2 diabetes mellitus. Which code set would be used for the diagnosis, and what example code is commonly used?
2 A provider performs an established patient office visit coded as 99213. Is this an ICD-10-CM, CPT, or HCPCS Level II code?
3 A patient receives crutches after an ankle injury, and the supply code is E0114. Which code set does this code belong to?
4 Explain why accurate provider documentation is more important than guessing the most likely diagnosis when assigning medical codes.

Sign in to save