N65.1 Disproportion of reconstructed breast

Billable ICD-10-CM code, FY2026.

Applicable to

• Breast asymmetry between native breast and reconstructed breast
• Disproportion between native breast and reconstructed breast

MS-DRG index

Defines the logic of DRG(s) 600-601 in MDC 09.

Approximate ICD-9-CM (GEMs)

• 612.1 Disproportion of reconstructed breast

Medicare Code Edits (MCE v43.1 (April 2026))

• Adult diagnoses (age 15 through 124): Age conflict edit. These diagnoses are clinically expected only in patients age 15 through 124.

Code annotations containing back-references to N65.1

Back-references to N65.1

• Type 1 Excludes: N62 Hypertrophy of breast ("disproportion of reconstructed breast (N65.1)")
• Type 1 Excludes: N64.81 Ptosis of breast ("ptosis of native breast in relation to reconstructed breast (N65.1)")
• Type 1 Excludes: N64.82 Hypoplasia of breast ("hypoplasia of native breast in relation to reconstructed breast (N65.1)")
• Type 1 Excludes: Z42.1 Encounter for breast reconstruction following mastectomy ("deformity and disproportion of reconstructed breast (N65.1-)")

Diagnosis Index entries for N65.1

• Asymmetry › between native and reconstructed breast
• Complication (s) (from) (of) › reconstructed breast › asymmetry between native and reconstructed breast
• Complication (s) (from) (of) › reconstructed breast › disproportion between native and reconstructed breast
• Disproportion › between native and reconstructed breast

Nearby codes

• N65 Deformity and disproportion of reconstructed breast
• N65.0 Deformity of reconstructed breast
• N65.1 Disproportion of reconstructed breast (this code)