CPT code 51605 denotes insertion of a chain into the urethra and/or bladder during contrast injection for urethrocystography, an X-ray study used to evaluate the urethra and bladder for anatomic or functional abnormalities. This diagnostic radiologic procedure is important nationally for evaluating causes of urinary obstruction, trauma, fistula, or recurrent infections that require direct contrast visualization of the lower urinary tract. Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare and Medicare. Readers will find a concise explanation of the clinical context and typical sites of service, plus a framework for interpreting common billing and coverage considerations that payers apply to contrast urethrocystography. The publication highlights coding context, common modifiers used with procedural imaging services, and typical clinical indications that underpin medical necessity determinations. It also outlines where to look for payer-specific edits, prior authorization triggers, and documentation elements that support claim adjudication. Data not available in the input is noted where necessary. This national overview is designed for billing professionals, radiology providers, and compliance officers seeking a clear, policy-focused summary of CPT code 51605 and its role in diagnostic evaluation of the lower urinary tract.