What ICD (International Classification of Diseases) codes are used for a thyroid ultrasound in a patient with a history of thyroid nodule for monitoring purposes?

ICD-10 Coding for Thyroid Ultrasound in Patients with History of Thyroid Nodule Under Surveillance

For a patient with a known history of thyroid nodule undergoing monitoring ultrasound, use ICD-10 code E04.1 (Nontoxic single thyroid nodule) or E04.2 (Nontoxic multinodular goiter) as the primary diagnosis code, depending on whether the patient has a solitary nodule or multiple nodules.

Primary Diagnosis Codes for Thyroid Nodule Surveillance

For Single Nodule

• E04.1 - Nontoxic single thyroid nodule is the appropriate code when monitoring a solitary benign thyroid nodule that has been previously characterized 1, 2
• This code applies when the nodule has been evaluated (typically with prior ultrasound and/or fine-needle aspiration) and determined to be benign, requiring periodic surveillance 2, 3

For Multiple Nodules

• E04.2 - Nontoxic multinodular goiter should be used when the patient has multiple thyroid nodules under surveillance 1, 3
• This code is appropriate for patients with multinodular thyroid disease requiring periodic ultrasound monitoring 3

Additional Relevant Codes Based on Clinical Context

If Prior Malignancy History

• Z85.850 - Personal history of malignant neoplasm of thyroid should be added as a secondary code if the patient has a history of treated thyroid cancer and is undergoing surveillance for recurrence 1
• This code is critical for patients who have undergone thyroidectomy or radioiodine ablation and require routine surveillance imaging 1

If Nodule Characteristics Are Suspicious

• D44.0 - Neoplasm of uncertain behavior of thyroid gland may be appropriate if the nodule has indeterminate features on prior imaging or cytology (Bethesda III or IV) and is being monitored before definitive intervention 2

If Symptoms Are Present

• R22.1 - Localized swelling, mass and lump, neck can be used if the patient has a palpable thyroid nodule causing concern 3
• R06.02 - Shortness of breath or R13.10 - Dysphagia, unspecified should be added if the nodule is causing compressive symptoms 1

Clinical Context That Determines Code Selection

Surveillance Intervals Guide Coding Appropriateness

• Ultrasound surveillance is typically recommended for nodules classified as Bethesda II (benign) on prior fine-needle aspiration, with very low malignancy risk of 1-3% 2, 3
• For nodules with suspicious ultrasound features (hypoechogenicity, microcalcifications, irregular margins, solid composition), more frequent monitoring may be indicated, and coding should reflect the higher suspicion level 2, 4

Size Considerations

• Nodules ≥2 cm warrant evaluation even without suspicious features due to increased malignancy risk, and this should be documented in the medical record to support the medical necessity of surveillance imaging 2, 3
• Nodules <1 cm without high-risk features typically do not require routine surveillance unless there are additional clinical risk factors 2

Common Coding Pitfalls to Avoid

• Do not use Z12.31 (Encounter for screening for malignant neoplasm of thyroid) for surveillance of known nodules, as this code is reserved for screening in asymptomatic patients without known thyroid disease 1
• Avoid using R93.89 (Abnormal findings on diagnostic imaging of other specified body structures) as the primary code, as this is too nonspecific when a definitive thyroid nodule diagnosis exists 1
• Do not code as "rule out thyroid cancer" (C73) unless there is pathologic confirmation of malignancy, as this can lead to insurance denials and inappropriate patient anxiety 1, 2

Documentation Requirements for Medical Necessity

• The medical record should document the nodule's prior characterization (size, ultrasound features, prior biopsy results if performed) to justify surveillance imaging 2, 3
• Document any changes in nodule size, symptoms, or patient risk factors (family history, radiation exposure) that support the need for repeat imaging 2, 3
• For patients with Bethesda II (benign) nodules, documentation should indicate the surveillance interval is appropriate based on nodule characteristics and clinical guidelines 2