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CPT 51798: Bladder Ultrasound to Measure Post‑Void Residual

CPT code 51798 denotes a diagnostic ultrasound procedure to measure post-void residual (PVR) urine volume in the bladder. This noninvasive assessment of retained urine is commonly used in urology and related specialties to evaluate voiding dysfunction, urinary retention, and neurologic bladder conditions. Nationally, PVR measurement is an important objective test that informs diagnosis and care pathways for patients with suspected urinary retention or incomplete bladder emptying.

Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise clinical context for the service, typical sites of care, and an overview of coding relationships. The publication summarizes payer coverage considerations, common clinical indications, and adjacent urodynamic procedures that may appear on the same claim lines.

This resource highlights how CPT code 51798 fits into urologic diagnostic workflows and billing practice. It provides benchmarks and policy-oriented content useful for billing staff, revenue cycle managers, and clinical leaders seeking to align documentation with coding and payer expectations. Where payer-specific policy or coverage details are available, they are summarized to help organizations identify potential authorization or bundling issues. Data not available in the input are noted where applicable.

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Billing Code Overview

CPT code 51798 describes an ultrasound measurement of post-void residual (PVR) urine volume. The procedure uses bladder ultrasound imaging to determine the amount of urine remaining after voluntary voiding.

Service type: Diagnostic bladder ultrasound to measure residual urine volume

Typical site of service: Outpatient clinic or office setting, urology clinic, or ambulatory imaging suite

National Reimbursement Benchmarks

Medicare’s mean allowed rate of $13.2 sits well below BUCA’s average commercial mean of $69.4, highlighting a substantial gap between federal reimbursements and an aggregated commercial benchmark. This spread underscores that Medicare pays at a fraction of the average commercial level for CPT 51798, with Medicare’s inter-locality spread concentrated around a narrow middle (P25 $12, P50 $13, P75 $14) while BUCA’s quartiles center near P25 $55.1, P50 $67.6, P75 $79.5.

Dispersion varies meaningfully across payers: Blue Cross Blue Shield shows the widest IQR (P75 $119.6 minus P25 $87.9 = $31.7), indicating larger variability in commercial contract rates, while Aetna’s IQR ($24.3 minus $10.7 = $13.6) and Cigna’s IQR ($26.5 minus $9.5 = $17.0) are moderate. UnitedHealth Group’s IQR ($27.5 minus $13.9 = $13.6) is similar to Aetna, and BUCA’s IQR ($79.5 minus $55.1 = $24.4) is sizeable but below BCBS.

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CPT 51798: Bladder Ultrasound to Measure Post‑Void Residual

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Billing Code Overview

Service type: Diagnostic bladder ultrasound to measure residual urine volume

Typical site of service: Outpatient clinic or office setting, urology clinic, or ambulatory imaging suite

National Reimbursement Benchmarks

National Payer Mean Reimbursement Rates

Clinical & Coding Specifications

Clinical Context

A 68-year-old male with a history of diabetes mellitus and suspected neurogenic bladder presents to the urology clinic with urinary retention and incomplete bladder emptying. The treating urologist orders a post-void bladder scan to quantify post-void residual urine volume using a portable bladder ultrasound prior to decisions about catheterization or further urodynamic testing. The typical workflow: patient voids in restroom, returns to clinic; a trained clinician (urologist or trained nurse/technician) performs a noninvasive transabdominal bladder ultrasound using a portable device. The measured residual volume is recorded in the medical record. Results guide immediate clinical actions (intermittent catheterization, indwelling catheter placement, medication adjustment) and inform need for additional testing such as comprehensive urodynamics or referral to female pelvic medicine or pediatric urology when applicable. Typical site of service is outpatient clinic or office and may also occur in the emergency department, inpatient ward, or ambulatory procedure area.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When reporting only the physician’s interpretation of the scan separated from facility imaging charges
`50`	Bilateral procedure	When a bilateral procedure modifier is clinically required (rare for bladder ultrasound)
`52`	Reduced services	When the ultrasound is partially reduced in scope or duration compared to usual practice
`53`	Discontinued procedure	When the scan was started but terminated because of patient instability or other valid reason
`59`	Distinct procedural service	When this ultrasound is separately identifiable from other services on the same day
`76`	Repeat procedure by same physician	When the same provider repeats the bladder scan within the same session or visit
`77`	Repeat procedure by another physician	When a different provider repeats the scan during the same encounter
`91`	Repeat clinical diagnostic laboratory test	When a repeat bladder volume measurement is performed to confirm prior result (note: `91` is lab-specific but sometimes used for repeat diagnostic tests per payer policy)
`25`	Significant, separately identifiable E/M service	When a significant evaluation and management service is performed the same day as the bladder scan
`59`	Distinct procedural service	When the bladder ultrasound is a separate procedure from other imaging or interventions performed the same day
`76`	Repeat procedure by same physician	When a subsequent scan is required during the same visit to assess change in volume

Taxonomy Code	Specialty	Notes
`208800000X`	Urology Physician	Primary specialty performing and interpreting bladder ultrasound in adults
`2088P0231X`	Pediatric Urology Physician	Performs bladder residual measurements in pediatric patients with neurogenic bladder
`2088F0040X`	Female Pelvic Medicine and Reconstructive Surgery Physician	Performs and interprets bladder scans in female pelvic floor and voiding dysfunction care

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`N31.0`	Uninhibited neuropathic bladder, not elsewhere classified	Neuropathic bladder can cause incomplete emptying; residual volume measurement documents retention severity
`N31.2`	Flaccid neuropathic bladder, not elsewhere classified	Flaccid bladder leads to urinary retention; bladder scan quantifies post-void residual to guide catheterization decisions
`N31.9`	Neuromuscular dysfunction of bladder, unspecified	General neuromuscular bladder dysfunction often requires residual urine assessment as part of management
`N32.0`	Bladder-neck obstruction	Obstruction at the bladder neck can cause elevated post-void residual; bladder ultrasound helps assess degree of retention

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`51792`	Electromyography (EMG) of anal or urethral sphincter muscles (urodynamic procedure)	Performed as part of comprehensive urodynamic assessment when neuromuscular dysfunction of the bladder is suspected; complements residual volume measurement
`51797`	Urodynamic procedure, complex cystometrogram or other bladder function testing	Neighboring urodynamic procedure used when more detailed assessment of bladder storage and voiding is required beyond a residual volume scan

CPT 51725: Cystometrogram — Bladder Pressure and Capacity Test

CPT-51726-CYSTOMETRY-BLADDER-PRESSURE-TESTING

CPT 51726: Cystometry for Bladder Capacity and Pressure Measurement

CPT-51727-COMPLEX-CYSTOMETROGRAM-URETHRAL-PRESSURE-PROFILE

CPT 51727: Complex Cystometrogram with Urethral Pressure Profile

CPT-51728-COMPLEX-CYSTOMETROGRAM-VOIDING-PRESSURE-STUDIES

CPT 51728: Complex Cystometrogram with Voiding Pressure Studies

CPT-51729-COMPLEX-CYSTOMETROGRAM-VOIDING-URETHRAL-PRESSURE-PROFILE

CPT 51729: Complex Cystometrogram with Voiding and Urethral Pressure Studies

CPT-51736-UROFLOWMETRY-URODYNAMIC-FLOW-STUDY

CPT 51736: Uroflowmetry (Urodynamic Flow Study)

CPT-51741-UROFLOWMETRY-URINARY-FLOW-MEASUREMENT

CPT 51741: Uroflowmetry (Urinary Flow Measurement)

CPT-51784-ANAL-OR-URETHRAL-SPHINCTER-ELECTRICAL-ACTIVITY-TESTING

CPT 51784: Anal or Urethral Sphincter Electrical Activity Testing

CPT-51785-ANAL-URETHRAL-SPHINCTER-ELECTROMYOGRAPHY

CPT 51785: Electromyography of Anal or Urethral Sphincter

CPT-51792-SPHINCTER-ELECTROMYOGRAPHY-ANAL-URETHRAL

CPT 51792: Electromyography of Anal or Urethral Sphincter Muscles

Showing 1–10 of 11

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When reporting only the physician’s interpretation of the scan separated from facility imaging charges
`50`	Bilateral procedure	When a bilateral procedure modifier is clinically required (rare for bladder ultrasound)
`52`	Reduced services	When the ultrasound is partially reduced in scope or duration compared to usual practice
`53`	Discontinued procedure	When the scan was started but terminated because of patient instability or other valid reason
`59`	Distinct procedural service	When this ultrasound is separately identifiable from other services on the same day
`76`	Repeat procedure by same physician	When the same provider repeats the bladder scan within the same session or visit
`77`	Repeat procedure by another physician	When a different provider repeats the scan during the same encounter
`91`	Repeat clinical diagnostic laboratory test	When a repeat bladder volume measurement is performed to confirm prior result (note: `91` is lab-specific but sometimes used for repeat diagnostic tests per payer policy)
`25`	Significant, separately identifiable E/M service	When a significant evaluation and management service is performed the same day as the bladder scan
`59`	Distinct procedural service	When the bladder ultrasound is a separate procedure from other imaging or interventions performed the same day
`76`	Repeat procedure by same physician	When a subsequent scan is required during the same visit to assess change in volume

Taxonomy Code	Specialty	Notes
`208800000X`	Urology Physician	Primary specialty performing and interpreting bladder ultrasound in adults
`2088P0231X`	Pediatric Urology Physician	Performs bladder residual measurements in pediatric patients with neurogenic bladder
`2088F0040X`	Female Pelvic Medicine and Reconstructive Surgery Physician	Performs and interprets bladder scans in female pelvic floor and voiding dysfunction care

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`N31.0`	Uninhibited neuropathic bladder, not elsewhere classified	Neuropathic bladder can cause incomplete emptying; residual volume measurement documents retention severity
`N31.2`	Flaccid neuropathic bladder, not elsewhere classified	Flaccid bladder leads to urinary retention; bladder scan quantifies post-void residual to guide catheterization decisions
`N31.9`	Neuromuscular dysfunction of bladder, unspecified	General neuromuscular bladder dysfunction often requires residual urine assessment as part of management
`N32.0`	Bladder-neck obstruction	Obstruction at the bladder neck can cause elevated post-void residual; bladder ultrasound helps assess degree of retention

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`51792`	Electromyography (EMG) of anal or urethral sphincter muscles (urodynamic procedure)	Performed as part of comprehensive urodynamic assessment when neuromuscular dysfunction of the bladder is suspected; complements residual volume measurement
`51797`	Urodynamic procedure, complex cystometrogram or other bladder function testing	Neighboring urodynamic procedure used when more detailed assessment of bladder storage and voiding is required beyond a residual volume scan

CPT 51725: Cystometrogram — Bladder Pressure and Capacity Test

CPT-51726-CYSTOMETRY-BLADDER-PRESSURE-TESTING

CPT 51726: Cystometry for Bladder Capacity and Pressure Measurement

CPT-51727-COMPLEX-CYSTOMETROGRAM-URETHRAL-PRESSURE-PROFILE

CPT 51727: Complex Cystometrogram with Urethral Pressure Profile

CPT-51728-COMPLEX-CYSTOMETROGRAM-VOIDING-PRESSURE-STUDIES

CPT 51728: Complex Cystometrogram with Voiding Pressure Studies

CPT-51729-COMPLEX-CYSTOMETROGRAM-VOIDING-URETHRAL-PRESSURE-PROFILE

CPT 51729: Complex Cystometrogram with Voiding and Urethral Pressure Studies

CPT-51736-UROFLOWMETRY-URODYNAMIC-FLOW-STUDY

CPT 51736: Uroflowmetry (Urodynamic Flow Study)

CPT-51741-UROFLOWMETRY-URINARY-FLOW-MEASUREMENT

CPT 51741: Uroflowmetry (Urinary Flow Measurement)

CPT-51784-ANAL-OR-URETHRAL-SPHINCTER-ELECTRICAL-ACTIVITY-TESTING

CPT 51784: Anal or Urethral Sphincter Electrical Activity Testing

CPT-51785-ANAL-URETHRAL-SPHINCTER-ELECTROMYOGRAPHY

CPT 51785: Electromyography of Anal or Urethral Sphincter

CPT-51792-SPHINCTER-ELECTROMYOGRAPHY-ANAL-URETHRAL

CPT 51792: Electromyography of Anal or Urethral Sphincter Muscles

Showing 1–10 of 11

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

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CPT 51798: Bladder Ultrasound to Measure Post‑Void Residual

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Billing Code Overview

National Reimbursement Benchmarks

OpenPayer

CPT 51798: Bladder Ultrasound to Measure Post‑Void Residual

Sign up for cpt 51798 policy alerts

Billing Code Overview

National Reimbursement Benchmarks

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References