🧬 ICD-10 CM K80.51 — Calculus of Bile Duct Without Cholangitis or Cholecystitis With Obstruction
Billable Code Confirmed
Non-Billable Parent Codes
K80 (Cholelithiasis) is a non-billable category header — it requires additional characters to specify gallbladder vs. bile duct involvement and the presence of cholecystitis/cholangitis. K80.5 (Calculus of bile duct without cholecystitis) is non-billable at 4 characters — it still needs the Fourth character for cholangitis status and the Fifth for obstruction.
Clinical Context
The clinical distinction driving K80.51 selection is a stone lodged in the common bile duct causing mechanical obstruction, with no documented cholangitis (infection) or cholecystitis (gallbladder inflammation). If either complication is documented, the encounter moves to the K80.3x (cholangitis) or K80.6x/K80.7x (with cholecystitis) family instead.
Code Classification
This is a diagnosis code (ICD-10-CM), not a procedure code. It reports the underlying condition; any ERCP or surgical intervention performed to relieve the obstruction is captured separately with CPT codes.
🔍 Code Description
ICD-10 CM K80.51 captures a stone within the common bile duct that is producing obstructive symptoms — typically colicky right upper quadrant pain, nausea, and possible jaundice or elevated liver enzymes — without any evidence of superimposed infection or gallbladder inflammation. The obstruction distinction (fifth character “1”) matters clinically and financially because it signals a more urgent presentation than K80.50, often prompting same-admission 43264 ERCP intervention rather than elective outpatient management.
Coders should differentiate this from the broader K80.7 family, which applies when calculi are present in both the gallbladder and the bile duct simultaneously. Documentation review is essential: if the attending’s note mentions “cholangitis” or “ascending infection” anywhere in the chart, K80.51 is the wrong code and the encounter should map instead to the K80.3x cholangitis subcategory, which carries a very different DRG and clinical severity profile.
🌳 Code Tree / Hierarchy
K80 Cholelithiasis ❌ Non-billable
│
├── K80.0- Calculus of gallbladder with acute cholecystitis ✅ Billable (with 6th char)
├── K80.1- Calculus of gallbladder with chronic cholecystitis ✅ Billable (with 6th char)
├── K80.2- Calculus of gallbladder without cholecystitis ✅ Billable (with 6th char)
│
├── K80.5 Calculus of bile duct without cholecystitis ❌ Non-billable
│ │
│ ├── K80.50 Calculus of bile duct w/o cholangitis or cholecystitis, w/o obstruction ✅ Billable
│ └── K80.51 Calculus of bile duct w/o cholangitis or cholecystitis, w obstruction ◀ THIS CODE ✅ Billable
│
├── K80.3- Calculus of bile duct with cholangitis ✅ Billable (with 6th char)
└── K80.6-/K80.7- Calculus of gallbladder and bile duct ✅ Billable (with 6th char)Fourth vs. Fifth Character Precision
The fourth character in the K80.5 subcategory answers “is there cholangitis?” (always “no” here), while the fifth character answers “is there obstruction?” Missing the fifth character digit is one of the most common denials seen on biliary claims — the code simply won’t process as billable without it.
Tip
Always cross-check imaging (ultrasound, MRCP, or ERCP findings) against the physician’s final diagnosis statement — radiology may describe “dilated CBD” without the provider explicitly documenting “obstruction,” which can create a query opportunity.
✅ Includes
- Choledocholithiasis, obstructive type — a bile duct stone physically blocking flow, confirmed by imaging or direct visualization at ERCP.
- Hepatic colic (recurrent), without cholangitis or cholecystitis — recurring biliary-type pain attributable to the obstructing calculus itself.
❌ Excludes
Excludes 1
K91.86 — Retained cholelithiasis following cholecystectomy. This is mutually exclusive because K80.51 assumes a native, non-postsurgical biliary system; a retained stone after prior cholecystectomy is captured under the postprocedural complication code instead.
Danger
The most common Excludes1 error is coding K80.51 for a patient with a history of cholecystectomy who re-presents with a bile duct stone. Always check the surgical history section of the H&P before finalizing — if the gallbladder is already absent, K91.86 takes precedence.
Excludes 2
No Excludes2 notes apply directly to this subcategory; concurrent conditions such as acute pancreatitis (K85.90) may be coded together with K80.51 when clinically documented, since gallstone pancreatitis is a distinct, separately reportable complication.
📋 Clinical Overview
Obstruction vs. No Obstruction vs. Cholangitis
This table clarifies the three-way distinction inpatient coders most often confuse within the K80.3–K80.5 range, since all three present with similar biliary colic symptomatology but carry different severity and DRG implications.
| Feature | K80.51 | Related K80.50 | Related K80.31 |
|---|---|---|---|
| Obstruction | Present | Absent | Present |
| Infection (cholangitis) | Absent | Absent | Present (unspecified type) |
| Typical acuity | Urgent — often same-admission ERCP | Can be managed electively | Emergent — sepsis risk, often requires urgent ERCP + antibiotics |
Important
A CDI trigger fires when labs show elevated bilirubin/alkaline phosphatase with fever or leukocytosis — this pattern should prompt a query for cholangitis, since undercoding K80.51 when cholangitis is actually present significantly understates severity and DRG weight.
Manifestations & Symptom Burden
- Biliary colic — episodic, severe RUQ or epigastric pain, often postprandial, lasting 30 minutes to several hours.
- Jaundice — scleral icterus or skin yellowing from obstructed bilirubin outflow.
- Nausea/vomiting — commonly accompanies the colicky pain episodes.
- Dark urine/clay-colored stool — classic obstructive pattern from impaired bile excretion.
Tip
Jaundice alone does not automatically imply cholangitis — code only what is explicitly documented; don’t infer infection from obstruction symptoms alone.
💰 HCC Risk Adjustment
ICD-10 CM K80.51 is not HCC-mapped under the current CMS-HCC V28 model. Uncomplicated obstructive choledocholithiasis carries no RAF coefficient and has no bearing on Medicare Advantage capitation payments. It remains fully reportable and clinically necessary to document for accurate severity-of-illness and DRG assignment, but risk-adjustment capture workflows can bypass this code without financial consequence to RAF scoring.
🏥 MS-DRG Assignment
| DRG | Title | Tier |
|---|---|---|
| 444 | Disorders of the Biliary Tract with MCC | Highest weight |
| 445 | Disorders of the Biliary Tract with CC | Mid weight |
| 446 | Disorders of the Biliary Tract without CC/MCC | Base weight |
ICD-10 CM K80.51 groups to MDC 07 — Hepatobiliary System and Pancreas. As principal diagnosis, DRG tier is driven entirely by secondary diagnoses documented as CC or MCC (e.g., acute kidney injury, sepsis, or significant comorbidities) — the diagnosis code itself carries no inherent severity beyond the obstruction designation. A common pitfall is under-DRG’ing the stay by failing to capture a qualifying secondary CC/MCC that was clinically present but not coded.
- NCD/LCD note: There is no national coverage determination governing K80.51 as a diagnosis. Medical necessity for the associated therapeutic procedure (typically ERCP, CPT 43264) is addressed at the Noridian JE/JF LCD level and should be verified against the current local coverage article before claim submission, particularly for repeat ERCP within the same admission.
🔗 Related ICD-10-CM Codes
Same subcategory / obstruction spectrum:
- K80.50 — Calculus of bile duct without cholangitis or cholecystitis, without obstruction
- K80.31 — Calculus of bile duct with unspecified cholangitis, with obstruction
- K80.33 — Calculus of bile duct with acute cholangitis, with obstruction
Combined gallbladder + bile duct calculi:
- K80.70 — Calculus of gallbladder and bile duct without cholecystitis, without obstruction
- K80.71 — Calculus of gallbladder and bile duct without cholecystitis, with obstruction
- K80.67 — Calculus of gallbladder and bile duct with acute and chronic cholecystitis, with obstruction
🛠️ Commonly Associated CPT Codes
- 43264 — ERCP with removal of calculus/calculi from bile duct; the primary interventional code for K80.51 when endoscopic stone extraction is performed.
- 43262 — ERCP with sphincterotomy/papillotomy; frequently bundled with stone extraction to widen the ampullary opening.
- 43274 — ERCP with placement of biliary stent; used when the stone cannot be fully cleared and temporary drainage is needed.
- 47563 — Laparoscopic cholecystectomy with cholangiography; relevant if concurrent gallbladder pathology prompts combined surgical management.
- 47564 — Laparoscopic cholecystectomy with exploration of common bile duct; used when operative CBD exploration accompanies cholecystectomy.
- 47420 — Choledochotomy/choledochostomy with exploration or removal of calculus (open approach); reserved for cases where ERCP is unsuccessful or unavailable.
- 74328 — Endoscopic catheterization of the biliary ductal system, radiological supervision and interpretation; reported alongside ERCP when formal cholangiography imaging is performed.
🏷️ Modifier Reference
Detail Rule: Biliary tract procedures** are midline/single-system — laterality modifiers (-RT/-LT/-50) and eyelid modifiers (-E1--E4) are not applicable and are excluded below.
| Modifier | Name | When to Apply |
|---|---|---|
| -59 | Distinct Service | Apply when a separately identifiable procedure (e.g., sphincterotomy) is performed at a different session or on a distinct structure not normally bundled with the primary ERCP. |
| -51 | Multiple Procedures | Apply when reporting more than one significant procedure during the same ERCP session, subject to payer-specific bundling rules. |
| -52 | Reduced Services | Apply if the endoscopist was unable to complete the full scope of the planned procedure due to anatomic difficulty. |
| -53 | Discontinued | Apply when the ERCP is terminated early due to patient risk or clinical instability before completion. |
| -58 | Staged | Apply when a planned, related follow-up procedure (e.g., a second ERCP for stent removal) occurs during the postoperative period. |
| -78 | Return to OR | Apply when the patient requires an unplanned return to the procedure suite for a related complication within the global period. |
| -79 | Unrelated Procedure | Apply when a separate, unrelated procedure is performed during the same postoperative period as a prior biliary intervention. |
| -25 | Significant E/M | Apply when a significant, separately identifiable E/M service is provided by the same physician on the same day as the ERCP. |
| -24 | Unrelated E/M | Apply when an unrelated E/M service occurs during the global period of an already-billed biliary procedure. |
NCCI Bundling Considerations
Diagnostic ERCP (43260) is bundled into therapeutic ERCP codes like 43264 when performed at the same session; modifier -59 is only appropriate when a truly distinct, separately reportable service is documented — not simply because two CPT codes appear on the same claim.
🔬 ICD-10-PCS Crosswalk
- 0FC98ZZ — Extirpation of matter from common bile duct, via natural or artificial opening endoscopic; used when inpatient facility coding requires PCS for an ERCP-based stone extraction.
- 0FC97ZZ — Extirpation of matter from common bile duct, via natural or artificial opening; applies to non-endoscopic transhepatic or percutaneous stone removal approaches.
- 0F798ZZ — Dilation of common bile duct, via natural or artificial opening endoscopic; relevant when sphincterotomy/duct dilation accompanies stone removal.
💊 Coding Scenarios and Examples
Example 1
Clinical Scenario: A patient presents with acute RUQ pain and jaundice. Ultrasound confirms a dilated common bile duct with a visible stone. No fever, no elevated WBC, no cholangitis documented. Patient undergoes inpatient ERCP with sphincterotomy and stone extraction, admitted for 2-day stay.
| Field | Code | Rationale |
|---|---|---|
| CPT | 43264--59 | Therapeutic ERCP with stone extraction; modifier applied only if a distinct, separately billable component is documented beyond the bundled sphincterotomy. |
| PDx | K80.51 | Obstruction confirmed by imaging and direct ERCP visualization, no cholangitis documented anywhere in the chart. |
Tip
Sequence K80.51 as principal diagnosis since the obstruction is the reason for admission and the driver of the ERCP. CDI note: confirm the provider explicitly ruled out cholangitis in the assessment/plan to support this specific code choice over the K80.3x family.
Example 2
Clinical Scenario: Patient with prior cholecystectomy presents with recurrent biliary colic. MRCP shows a common bile duct stone causing obstruction. ERCP performed with sphincterotomy and stent placement due to difficult stone extraction.
| Field | Code | Rationale |
|---|---|---|
| CPT | 43274--58 | Biliary stent placement, staged modifier used if a planned follow-up ERCP for stent removal is anticipated within the global period. |
| CPT 2 | 43262 | Sphincterotomy performed to facilitate stent placement and future stone clearance. |
| PDx | K80.51 | Post-cholecystectomy status does not change this code, since the stone is native to the bile duct, not a retained postsurgical stone (which would trigger K91.86 instead). |
Tip
Sequencing note: verify the operative report doesn’t describe the stone as “retained” from the original cholecystectomy — that documentation nuance changes the code entirely. CDI note: flag for provider clarification if documentation is ambiguous about stone origin (native vs. retained).
Example 3
Clinical Scenario: Elderly inpatient develops acute obstructive jaundice from a bile duct stone. ERCP attempted but discontinued mid-procedure due to hemodynamic instability; patient stabilized and scheduled for repeat attempt the following day.
| Field | Code | Rationale |
|---|---|---|
| CPT | 43264--53 | Discontinued procedure modifier applied since the ERCP was terminated before completion due to patient instability. |
| PDx | K80.51 | Obstruction remains the working diagnosis; the discontinued procedure doesn’t change the underlying diagnosis code. |
Tip
Sequencing explanation: report the discontinued procedure with -53, then a separate line item for the successful repeat ERCP the next day (no modifier needed on the second attempt if fully completed). CDI note: ensure documentation clearly states the reason for discontinuation to support modifier -53 on audit review.
⚠️ Coding Pitfalls and Tips
- Pitfall 1: Assigning K80.50 or the K80 parent when obstruction is clinically evident but not explicitly stated by the provider; Tips: Query the provider directly rather than inferring obstruction from imaging language like “dilated duct” alone.
- Pitfall 2: Missing a cholangitis diagnosis buried in a consult note, leading to under-coding severity with K80.51 instead of the correct K80.3x code; Tips: Review all specialist notes, not just the admitting H&P, before finalizing code selection.
- Pitfall 3: Coding K80.51 for a post-cholecystectomy patient without checking whether the stone is retained vs. newly formed; Tips: Cross-reference surgical history and operative findings to rule out K91.86.
- Pitfall 4: Failing to capture a qualifying CC/MCC secondary diagnosis, resulting in DRG 446 assignment when 444 or 445 was actually supported; Tips: Run a full chart review for comorbidities like AKI or sepsis before final DRG assignment.
- Pitfall 5: Applying laterality or eyelid modifiers inappropriately to biliary CPT codes out of template habit; Tips: Biliary procedures are midline single-system — never apply -RT/-LT/-50/-E1—E4 modifiers here.
- Pitfall 6: Assuming K80.51 is HCC-mapped and skipping documentation review because “it won’t affect RAF anyway”; Tips: Code it fully regardless of HCC status — MS-DRG reimbursement and clinical accuracy still depend on it.
📚 Sources
1. CMS. *ICD-10-CM Official Guidelines for Coding and Reporting FY2026.* Centers for Medicare & Medicaid Services; 2025. 2. CMS. *MS-DRG v43.0 Definitions Manual.* Centers for Medicare & Medicaid Services; 2025. 3. ICD10Data.com. *K80.51 — Calculus of bile duct without cholangitis or cholecystitis with obstruction.* 2026 edition. 4. Noridian Healthcare Solutions. *Local Coverage Determinations, JE/JF Jurisdictions.* Noridian MAC. 5. AAPC. *Risk Adjustment Search Tool, CMS-HCC V28 Model.* 2026.Sources listed above correspond to superscript citations throughout this note. Verify all Medicare payment figures against your current CMS PFS Lookup tool and applicable MAC LCD prior to claim submission. Please use the latest AAPC/AHIMA Coding Books to verify each code within this note.