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CPT code 45331: Sigmoidoscopy, with biopsy2026 Medicare rate & RVUs in King County, WA

Reports flexible sigmoidoscopy with one or more tissue biopsies when a clinician samples the rectum or distal colon for diagnosis.

CMS RVU26DEffective Oct 1, 2026One payment locality35.9K Medicare services in 2024

In King County, WA, Medicare pays $387.83 for 45331 in the office and $73.49 when it’s performed in a hospital or facility.

$387.83Office (non-facility)
$73.49Hospital or facility
+20.1%vs the national office rate ($322.99)

Check a contract rate as a % of Medicare · 45331 nationwide

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

We’ll open 45331 for the payment locality that covers the ZIP.

On this page 11 sections
  1. Rate in King County, WA
  2. What 45331 covers
  3. Compared with other areas
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Related codes
  8. Rate history
  9. Where it applies
  10. Billing questions
  11. Sources

What 45331 covers

A clinician advances a flexible endoscope through the anus to examine the rectum and distal colon, then collects mucosal tissue for analysis. Gastroenterologists and colorectal surgeons commonly perform this service in an endoscopy unit, hospital outpatient department, or office. Typical reasons include evaluating suspected colitis, unexplained rectal bleeding, or an abnormality seen on prior testing. The biopsy may involve one or multiple tissue samples during the same examination.

Report this code when the procedure includes tissue biopsy, rather than inspection alone; the number of samples does not determine separate units. The record should identify the sampled site and clinical reason, and support that tissue was obtained. The service has a 0-day global period, so same-day preoperative and postoperative care is included. When related endoscopies are performed together, CMS endoscopy-family pricing applies. Modifier 50 is inappropriate. Medicare does not pay an assistant at surgery for this service, and co-surgeon and team-surgery billing are not permitted.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

How King County, WA compares for 45331

Across 109 of 109 payment localities, the office rate for 45331 runs from $281.06 in Arkansas to $449.20 in San Benito County, CA. King County, WA pays $387.83. The RVUs are the same everywhere; the geographic indexes change the dollars.

45331 in King County, WA vs other payment areas
  1. King County, WA · this page$387.83
  2. Rest of Washington · Washington$337.26−$50.57
  3. Los Angeles, CA · California$374.40−$13.43
  4. Washington, DC area · District of Columbia$375.58−$12.25
  5. Miami, FL · Florida$341.67−$46.16
  6. Chicago, IL · Illinois$330.71−$57.12
  7. Manhattan, NY · New York$373.66−$14.17

Other areas in Washington first, then benchmark localities. Bars start at $0.

Every other payment area

45331 in every other Medicare payment locality
Payment localityOfficeFacility
AlaskaAlaska$357.70$84.87
AlabamaAlabama$285.80$61.64
ArkansasArkansas$281.06$61.00
ArizonaArizona$313.60$65.35
Bakersfield, CACalifornia$348.86$68.08
Chico, CACalifornia$348.45$67.67
El Centro, CACalifornia$348.47$67.69
Fresno, CACalifornia$348.45$67.67

45331 rates by state

Office rate range in each state. Select a state to see its payment localities.

MEWIVTNHMTNDMNMINYMARIWAIDWYSDIAILINOHPANJCTORNVUTCONEMOKYWVVAMDDECAAZNMKSOKARTNNCSCDCTXLAMSALGAFLAKHI

Explore a state

Local rates. Clear comparisons.

Hover or focus a tile to see its rate range. Select it to open the state’s fee schedule.

$281.06

$398.83

Color shows the midpoint of each state’s locality range.

View every state and territory as a table
45331 office rate range by state
State / territoryOffice rate rangeLocalities
AK$357.701
AL$285.801
AR$281.061
AZ$313.601
CA$348.45–$449.2029
CO$340.411
CT$346.371
DC$375.581
DE$319.321
FL$312.96–$341.673
GA$293.51–$328.542
GU$359.551
HI$359.551
IA$296.261
ID$298.021
IL$301.15–$334.454
IN$300.051
KS$293.671
KY$291.371
LA$290.45–$307.032
MA$337.54–$378.552
MD$326.35–$375.583
ME$298.72–$318.732
MI$299.12–$316.352
MN$327.851
MO$284.05–$309.503
MS$282.671
MT$322.981
NC$302.461
ND$320.211
NE$298.421
NH$333.931
NJ$350.80–$370.642
NM$300.581
NV$322.491
NY$307.54–$382.525
OH$298.561
OK$291.851
OR$320.47–$353.602
PA$299.67–$336.092
PR$326.011
RI$332.471
SC$300.911
SD$319.881
TN$295.231
TX$297.34–$338.848
UT$305.641
VA$316.83–$375.582
VI$326.011
VT$317.861
WA$337.26–$387.832
WI$307.941
WV$288.161
WY$321.771

See 45331 in every payment locality

How the 45331 rate is calculated

Each of 45331’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

How the rate is built · 45331

RVUs × geographic indexes × conversion factor

Office or facility?

Work1.11

1.11 RVUs× 1.000 GPCI

Practice expense8.42

8.42 RVUs× 1.000 GPCI

Malpractice0.14

0.14 RVUs× 1.000 GPCI

Adjusted RVUs

9.6700

Conversion factor

$33.4009

Medicare rate

$322.99

Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.

The exact King County, WA inputs and CMS source lines

PPRRVU2026_Oct_nonQPP.csv

5,499

Code
45331
Physician work
1.11
Practice expense
8.42
Malpractice
0.14

GPCI2026.csv

108

Locality
King County, WA
Physician work
1.050
Practice expense
1.227
Malpractice
0.817
Office calculation for 45331 in King County, WA
ComponentRVULocality factorAdjusted
Physician work1.11× 1.0501.1655
Practice expense8.42× 1.22710.3313
Malpractice0.14× 0.8170.1144
Total RVUs11.6112
Conversion factor× 33.4009

Office rate, King County, WA$387.83

Office: (1.11 × 1.05 + 8.42 × 1.227 + 0.14 × 0.817) × $33.4009 = $387.83

Facility: (1.11 × 1.05 + 0.75 × 1.227 + 0.14 × 0.817) × $33.4009 = $73.49

Open 45331 in the RVU calculator

Payment rules and modifiers for 45331

The CMS indicators that decide how 45331 is paid alongside other services.

CMS payment indicators · 45331

Sigmoidoscopy, with biopsy

RuleCMS valueWhat it means
Global period000Same-day global: pre- and post-op care on the day of the procedure is included.
Multiple procedures3Endoscopy family rules apply.
Bilateral (modifier 50)0The 150% bilateral adjustment doesn’t apply.
Assistant at surgery (80/81/82/AS)1Not paid (statutory restriction).
Co-surgeons (62)0Not permitted.
Team surgery (66)0Not permitted.
Professional/technical0Physician service: no professional/technical split.

What modifiers do to the payment

Modifier 51 · payment effect

With and without the modifier

45331 without 51 · national office

$322.99

Sigmoidoscopy, with biopsy

45331-51 · Second procedure: 50%

$161.50

When this isn’t the highest-valued procedure in the session, Medicare pays 50% of its fee schedule amount (the highest is paid at 100%).

When to use modifier 51

Codes related to 45331

Related codes aren’t interchangeable: bill the code that matches the service performed.

Codes related to 45331
CodeHow it relatesOffice range, King County, WA
Same family
45330Flexible sigmoidoscopy, diagnosticFlexible sigmoidoscopy for diagnostic inspection without biopsy or another intervention.$257.44
45333Flexible sigmoidoscopy, hot biopsy forceps removalFlexible sigmoidoscopy with polyp removal rather than tissue sampling alone.$439.69
Used instead
45305Proctosigmoidoscopy, rigid scope with biopsyBiopsy during proctosigmoidoscopy, using a different endoscopic examination.$234.08
45342Sigmoidoscopy, ultrasound-guided tissue samplingBiopsy performed with endoscopic ultrasound guidance during sigmoidoscopy.No office rate

How 45331 has changed in King County, WA

45331 · Office / nonfacility

$387.83

Effective 2026-10-01

The base rate is $64.37 higher than on 2025-10-01, moving from $323.46 to $387.83 (19.9%).

It is unchanged from the immediately preceding available release, effective 2026-07-01.

Base rate by release · bars start at $0 · select a bar to compare

One bar per available release, ordered by effective date. Missing rates remain gaps. These comparisons hold the code, setting and locality identifiers constant; they do not isolate which policy or input caused a change.

What changed, release by release

  1. January 1, 2026

    RVU26A

    $323.46changed to$387.83

    • Conversion factor 32.3465 changed to 33.4009
    • Work RVU 1.14 changed to 1.11
    • Practice expense RVU 7.11 changed to 8.42
    • Malpractice RVU 0.16 changed to 0.14
    • Work GPCI 1.043 changed to 1.050
    • Practice expense GPCI 1.220 changed to 1.227
    • Malpractice GPCI 0.853 changed to 0.817

    Held through RVU26B, RVU26C, RVU26D.

  2. January 1, 2025

    RVU25A

    $339.89changed to$323.46

    • Conversion factor 33.2875 changed to 32.3465
    • Practice expense RVU 7.29 changed to 7.11
    • Malpractice RVU 0.15 changed to 0.16

    Held through RVU25B, RVU25C, RVU25D.

  3. March 9, 2024

    RVU24AR

    $334.34changed to$339.89

    • Conversion factor 32.7442 changed to 33.2875

    Held through RVU24B, RVU24C, RVU24D.

  4. January 1, 2024

    RVU24A

    $344.63changed to$334.34

    • Conversion factor 33.8872 changed to 32.7442
    • Practice expense RVU 7.35 changed to 7.29
    • Malpractice RVU 0.14 changed to 0.15
    • Work GPCI 1.039 changed to 1.043
    • Practice expense GPCI 1.207 changed to 1.220
    • Malpractice GPCI 0.815 changed to 0.853

  5. January 1, 2023

    RVU23A

    $357.30changed to$344.63

    • Conversion factor 34.6062 changed to 33.8872
    • Practice expense RVU 7.58 changed to 7.35
    • Malpractice RVU 0.12 changed to 0.14
    • Work GPCI 1.036 changed to 1.039
    • Practice expense GPCI 1.194 changed to 1.207
    • Malpractice GPCI 0.776 changed to 0.815

    Held through RVU23B, RVU23C, RVU23D.

  6. January 1, 2022

    RVU22A

    $357.47changed to$357.30

    • Conversion factor 34.8931 changed to 34.6062
    • Practice expense RVU 7.50 changed to 7.58
    • Malpractice RVU 0.14 changed to 0.12

    Held through RVU22B, RVU22C, RVU22D.

  7. January 1, 2021

    RVU21A

    $323.42changed to$357.47

    • Conversion factor 36.0896 changed to 34.8931
    • Practice expense RVU 6.56 changed to 7.50
    • Malpractice RVU 0.13 changed to 0.14
    • Work GPCI 1.031 changed to 1.036
    • Practice expense GPCI 1.170 changed to 1.194
    • Malpractice GPCI 0.854 changed to 0.776

    Held through RVU21B, RVU21C, RVU21D.

  8. January 1, 2020

    RVU20A

    $307.83changed to$323.42

    • Conversion factor 36.0391 changed to 36.0896
    • Practice expense RVU 6.31 changed to 6.56
    • Malpractice RVU 0.15 changed to 0.13
    • Work GPCI 1.027 changed to 1.031
    • Practice expense GPCI 1.146 changed to 1.170
    • Malpractice GPCI 0.931 changed to 0.854

    Held through RVU20B, RVU20C, RVU20D.

  9. January 1, 2019

    RVU19A

    $297.60changed to$307.83

    • Conversion factor 35.9996 changed to 36.0391
    • Practice expense RVU 6.07 changed to 6.31

    Held through RVU19B, RVU19C, RVU19D.

  10. January 1, 2018

    RVU18AR1

    $292.84changed to$297.60

    • Conversion factor 35.8887 changed to 35.9996
    • Practice expense RVU 5.98 changed to 6.07
    • Work GPCI 1.026 changed to 1.027
    • Practice expense GPCI 1.151 changed to 1.146
    • Malpractice GPCI 0.713 changed to 0.931

    Held through RVU18B, RVU18C, RVU18D.

  11. January 1, 2017

    RVU17A

    $291.79changed to$292.84

    • Conversion factor 35.8043 changed to 35.8887
    • Work GPCI 1.025 changed to 1.026
    • Practice expense GPCI 1.155 changed to 1.151
    • Malpractice GPCI 0.495 changed to 0.713

    Held through RVU17B, RVU17C, RVU17D.

  12. January 1, 2016

    RVU16A

    $183.17changed to$291.79

    • Conversion factor 35.9335 changed to 35.8043
    • Work RVU 1.15 changed to 1.14
    • Practice expense RVU 3.32 changed to 5.98
    • Malpractice RVU 0.17 changed to 0.15

    Held through RVU16B, RVU16C, RVU16D.

  13. July 1, 2015

    RVU15C

    $182.26changed to$183.17

    • Conversion factor 35.7547 changed to 35.9335

    Held through RVU15D.

  14. January 1, 2015

    RVU15A

    $182.36changed to$182.26

    • Conversion factor 35.8228 changed to 35.7547
    • Practice expense RVU 3.30 changed to 3.32
    • Practice expense GPCI 1.150 changed to 1.155
    • Malpractice GPCI 0.688 changed to 0.495

    Held through RVU15B.

  15. January 1, 2014

    RVU14A

    $193.79changed to$182.36

    • Conversion factor 34.0230 changed to 35.8228
    • Practice expense RVU 3.81 changed to 3.30
    • Malpractice RVU 0.18 changed to 0.17
    • Practice expense GPCI 1.144 changed to 1.150
    • Malpractice GPCI 0.881 changed to 0.688

    Held through RVU14B, RVU14C, RVU14D.

  16. January 1, 2013

    RVU13AR

    Earliest loaded release: $193.79

    Held through RVU13B, RVU13C, RVU13D.

Rates in every CMS release
Effective fromOfficeFacilityCMS release
2026-10-01$387.83$73.49RVU26D
2026-07-01$387.83$73.49RVU26C
2026-04-01$387.83$73.49RVU26B
2026-01-01$387.83$73.49RVU26A
2025-10-01$323.46$77.21RVU25D
2025-07-01$323.46$77.21RVU25C
2025-04-01$323.46$77.21RVU25B
2025-01-01$323.46$77.21RVU25A
2024-10-01$339.89$78.76RVU24D
2024-07-01$339.89$78.76RVU24C
2024-04-01$339.89$78.76RVU24B
2024-03-09$339.89$78.76RVU24AR
2024-01-01$334.34$77.48RVU24A
2023-10-01$344.63$78.36RVU23D
2023-07-01$344.63$78.36RVU23C
2023-04-01$344.63$78.36RVU23B
2023-01-01$344.63$78.36RVU23A
2022-10-01$357.30$78.39RVU22D
2022-07-01$357.30$78.39RVU22C
2022-04-01$357.30$78.39RVU22B
2022-01-01$357.30$78.39RVU22A
2021-10-01$357.47$78.75RVU21D
2021-07-01$357.47$78.75RVU21C
2021-04-01$357.47$78.75RVU21B
2021-01-01$357.47$78.75RVU21A
2020-10-01$323.42$79.78RVU20D
2020-07-01$323.42$79.78RVU20C
2020-04-01$323.42$79.78RVU20B
2020-01-01$323.42$79.78RVU20A
2019-10-01$307.83$79.85RVU19D
2019-07-01$307.83$79.85RVU19C
2019-04-01$307.83$79.85RVU19B
2019-01-01$307.83$79.85RVU19A
2018-10-01$297.60$80.59RVU18D
2018-07-01$297.60$80.59RVU18C
2018-04-01$297.60$80.59RVU18B
2018-01-01$297.60$80.59RVU18AR1
2017-10-01$292.84$79.69RVU17D
2017-07-01$292.84$79.69RVU17C
2017-04-01$292.84$79.69RVU17B
2017-01-01$292.84$79.69RVU17A
2016-10-01$291.79$77.99RVU16D
2016-07-01$291.79$77.99RVU16C
2016-04-01$291.79$77.99RVU16B
2016-01-01$291.79$77.99RVU16A
2015-10-01$183.17$80.24RVU15D
2015-07-01$183.17$80.24RVU15C
2015-04-01$182.26$79.84RVU15B
2015-01-01$182.26$79.84RVU15A
2014-10-01$182.36$81.02RVU14D
2014-07-01$182.36$81.02RVU14C
2014-04-01$182.36$81.02RVU14B
2014-01-01$182.36$81.02RVU14A
2013-10-01$193.79$82.87RVU13D
2013-07-01$193.79$82.87RVU13C
2013-04-01$193.79$82.87RVU13B
2013-01-01$193.79$82.87RVU13AR

Price 45331 for an earlier date of service

Where the King County, WA rate applies

King County, WA is a Medicare payment area, not a city. Our Census mapping connects it to 63 cities and communities in Washington. Some span more than one payment area; confirm with the service ZIP.

  • Seattle
  • Algona
  • Ames Lake
  • 45331 in Auburn · multiple payment areas
  • Baring
  • Beaux Arts Village
  • Bellevue
  • Black Diamond

Browse all communities in Washington

45331 billing questions

How does this differ from diagnostic sigmoidoscopy?

Use 45331 when the flexible examination includes tissue sampling. Use 45330 when the examination is diagnostic without biopsy or another reportable intervention.

Can multiple biopsy samples be reported as multiple units?

No. The code covers one or multiple biopsies during the sigmoidoscopy; the number of specimens alone does not create additional units.

Can the biopsy and a polypectomy be reported together?

A biopsy that is simply part of removing the same lesion should not be represented separately as a diagnostic biopsy. Distinct sampling or treatment requires documentation of what was done and where.

Should modifier 50 be used for biopsies on both sides?

No. CMS identifies bilateral adjustment as inappropriate for this code, and modifier 50 should not be used.

Is same-day care included in the payment?

Yes. The 0-day global period includes same-day preoperative and postoperative care.

Can an assistant surgeon or co-surgeon be billed?

Medicare does not pay an assistant at surgery for this service. Co-surgeon and team-surgery billing are not permitted.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Show the CMS file lines behind this rate
RVUs for 45331PPRRVU2026_Oct_nonQPP.csv, line 5,499 (RVU26D)
Geographic factors for King County, WAGPCI2026.csv, line 108 (RVU26D)

Open CMS sourceHow we calculate rates

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