ICD-10-CM > S00-T88 > S30-S39 > S31 > S31.0 > S31.02 > S31.021 S31.021 Laceration with foreign body of lower back and pelvis with penetration into retroperitoneum Non-Billable/Non-Specific Codes S31.021A..., initial encounterS31.021D..., subsequent encounterS31.021S..., sequela