ICD-10-CM > S00-T88 > S30-S39 > S31 > S31.0 > S31.00 > S31.001 S31.001 Unspecified open wound of lower back and pelvis with penetration into retroperitoneum Non-Billable/Non-Specific Codes S31.001A..., initial encounterS31.001D..., subsequent encounterS31.001S..., sequela