ICD-10-CM > S00-T88 > S20-S29 > S20 > S20.3 > S20.34 > S20.344 S20.344 External constriction of middle front wall of thorax Non-Billable/Non-Specific Codes S20.344A..., initial encounterS20.344D..., subsequent encounterS20.344S..., sequela