CPT code 45321 denotes proctosigmoidoscopic decompression of a sigmoid volvulus, an endoscopic procedure that examines the anus, rectum, and sigmoid colon with a rigid proctosigmoidoscope and relieves torsion causing bowel obstruction. This procedure is clinically important for urgent management of sigmoid volvulus, as timely decompression can avert ischemia, perforation, and the need for emergent resection.

Key payers covered in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The content outlines clinical context and typical sites of service, and summarizes billing and coding considerations relevant for national payers. Readers will find a concise explanation of the procedure and service type, guidance on typical settings where the service is delivered, and identification of common modifier usage when available in the input. The summary also points readers to sections that cover billing benchmarks, reimbursement context, and clinical indications when those data are present.

Data not available in the input for associated taxonomies, specific ICD-10 diagnosis pairings, and payer-specific reimbursement rates are noted elsewhere. This national-level brief is intended to provide clinicians, coders, and policy stakeholders with a clear understanding of what CPT code 45321 represents and where it typically applies in care delivery.