🧬 ICD-10 CM K91.86 — Retained Cholelithiasis Following Cholecystectomy
Billable Code Confirmed
ICD-10 CM K91.86 is a complete, 5-character billable code effective through FY2026. No further specificity or additional characters are required — this is a stand-alone terminal code within the K91.8 subcategory.
Non-Billable Parent Codes
K91 — the category-level code for intraoperative/postprocedural digestive complications; too broad to report, requires a valid subcategory. K91.8 — “Other intraoperative and postprocedural complications and disorders of digestive system”; this 4-character stem requires a 5th/6th character to identify the specific complication and cannot be billed on its own.
Clinical Context
The distinguishing clinical fact driving code selection is sequence: a stone found after cholecystectomy, in a patient who no longer has a gallbladder, is coded here rather than to any K80 cholelithiasis code, which assumes an intact biliary system.
Code Classification
This is a diagnosis code describing a postoperative/postprocedural complication of a prior digestive-system surgery — not a procedure code. It documents a condition, not the intervention used to treat it.
🔍 Code Description
Retained cholelithiasis following cholecystectomy describes a bile duct stone (choledocholithiasis) that persists or is newly identified in the common bile duct after the gallbladder has already been surgically removed. Stones can be missed at the time of the original 47562 or 47563 cholecystectomy — particularly when intraoperative cholangiography was not performed or was inconclusive — or they may form or migrate into the duct in the postoperative period. Presentation ranges from asymptomatic incidental finding on imaging to jaundice, right-upper-quadrant pain, or ascending cholangitis requiring urgent intervention.
Because the gallbladder is no longer the source organ, this code sits outside the K80 cholelithiasis family entirely and instead falls under intraoperative/postprocedural complications. Documentation should clearly link the stone to a prior cholecystectomy for the coder to assign K91.86 rather than defaulting to an unspecified digestive complication code; if the note is ambiguous about timing relative to the original surgery, a physician query is warranted before finalizing the diagnosis code.
🌳 Code Tree / Hierarchy
K91 Intraoperative and postprocedural complications and disorders of digestive system, NEC ❌ Non-billable
│
├── K91.81 Other intraoperative complications of digestive system ❌ Non-billable (requires 6th character)
├── K91.82 Postprocedural hepatic failure ✅ Billable
├── K91.83 Postprocedural hepatorenal syndrome ✅ Billable
│
├── K91.8 Other intraoperative and postprocedural complications and disorders of digestive system ❌ Non-billable
│ │
│ ├── K91.85 Postprocedural stricture of digestive system ✅ Billable
│ ├── K91.86 Retained cholelithiasis following cholecystectomy ◀ THIS CODE ✅ Billable
│ └── K91.87 Postprocedural hematoma and seroma of a digestive system organ or structure ❌ Non-billable (requires 6th character)
│
└── K91.89 Other postprocedural complications and disorders of digestive system ✅ BillableSequencing Insight
Tip
If the retained stone triggers acute cholangitis, sepsis, or postprocedural hemorrhage during the same admission, code that complication as an additional diagnosis — it, not K91.86 itself, is usually what pushes the case into the MCC/CC DRG tiers.
✅ Includes
A stone retained in the common bile duct that is discovered after the gallbladder has been removed, whether missed at the original operation or newly formed/migrated postoperatively. Documentation of “post-cholecystectomy choledocholithiasis” or “retained CBD stone s/p 47562” both map here.
❌ Excludes
Excludes 1
K80 — Cholelithiasis. Mutually exclusive because K80 codes presume the gallbladder (and native biliary anatomy) is still present; K91.86 by definition requires a prior cholecystectomy.
Danger
The most common Excludes 1 error is coding K80.7-family calculus-of-gallbladder-and-bile-duct codes for a patient whose op note or history clearly documents a prior cholecystectomy. Always confirm cholecystectomy status in the H&P or problem list before finalizing either code family.
Excludes 2
No Excludes 2 notes are published for K91.86 in the FY2026 tabular.
📋 Clinical Overview
Retained Stone vs. Primary Cholelithiasis
The table below highlights why anatomic status (gallbladder present vs. absent) is the deciding factor between these code families, since symptoms alone often overlap.
| Feature | K91.86 | Related K80.20 (gallbladder calculus, no cholecystitis) | Related K80.70 (gallbladder + bile duct calculus) |
|---|---|---|---|
| Gallbladder status | Absent (post-cholecystectomy) | Present | Present |
| Typical trigger | Missed stone at original surgery or new stone formation postop | Native gallstone disease | Combined gallbladder and duct stones |
| Common intervention | ERCP stone extraction (43264) | Cholecystectomy | Cholecystectomy ± ERCP |
Important
A CDI trigger fires whenever a post-cholecystectomy patient is imaged or scoped for “possible retained stone” but the final diagnosis documentation only says “choledocholithiasis” without referencing the prior surgery — query the physician to confirm whether K91.86 or an unrelated new-onset duct stone code applies.
Manifestations & Symptom Burden
Jaundice from biliary obstruction; right-upper-quadrant or epigastric pain; elevated liver enzymes (alkaline phosphatase, bilirubin) on labs; fever/rigors if ascending cholangitis develops; pancreatitis if the stone impacts the ampulla.
Tip
Code the manifestation (e.g., obstructive jaundice, acute pancreatitis, cholangitis) as an additional diagnosis when documented — it is not inherent to K91.86 and materially affects CC/MCC capture.
💰 HCC Risk Adjustment
ICD-10 CM K91.86 is not mapped under the current CMS-HCC V28 model. It is a discrete, typically acute postprocedural finding rather than a chronic condition, so it carries no RAF weight and requires no annual recapture. It remains fully reportable and relevant for inpatient severity and quality metrics — just not for risk-adjustment revenue.
🏥 MS-DRG Assignment
| DRG | Title | Tier |
|---|---|---|
| 393 | Other Digestive System Diagnoses | With MCC |
| 394 | Other Digestive System Diagnoses | With CC |
| 395 | Other Digestive System Diagnoses | Without CC/MCC |
ICD-10 CM K91.86 groups to MDC 06 (Digestive System) via DRGs 393–395 — not MDC 07 (Hepatobiliary/Pancreas), which is an easy misstep given the biliary subject matter. As principal diagnosis, the DRG tier is driven entirely by whether a documented secondary diagnosis meets MCC or CC criteria (e.g., cholangitis, sepsis, acute pancreatitis, postprocedural hemorrhage). If an ERCP or surgical bile-duct exploration performed during the stay qualifies as an OR procedure, confirm the grouper doesn’t redirect the case to a surgical DRG instead. There is no diagnosis-specific NCD for K91.86; coverage for the associated ERCP/stone-extraction procedure runs through your Noridian (JE/JF) LCD/Local Coverage Article for GI endoscopy — check the current active policy before submission.
🔗 Related ICD-10-CM Codes
Prior surgery / status:
- Z98.0 — Postprocedural status, gastrointestinal (use if documenting cholecystectomy history separately)
- K91.89 — Other postprocedural complications and disorders of digestive system
Complications that may co-occur:
- K80.30 — Calculus of bile duct with cholangitis, unspecified, without obstruction (only if genuinely a new duct stone, not the retained one)
- K83.0 — Cholangitis
- K85.10 — Biliary acute pancreatitis without necrosis or infection, without bleeding
🛠️ Commonly Associated CPT Codes
- 43260 — ERCP, diagnostic; billing note: baseline visualization code, typically bundled once a therapeutic ERCP code is reported same session.
- 43262 — ERCP with sphincterotomy/papillotomy; billing note: commonly performed to enable stone extraction access.
- 43264 — ERCP with endoscopic retrograde removal of stone(s)/debris from biliary/pancreatic duct; billing note: the primary therapeutic code for retained stone extraction.
- 43265 — ERCP with endoscopic retrograde destruction of calculi (lithotripsy); billing note: use when mechanical or laser lithotripsy is required for large/impacted stones.
- 43268 — ERCP with endoscopic placement of stent into biliary/pancreatic duct; billing note: use when a temporary stent is placed to ensure drainage after extraction.
- 47425 — Exploration of common bile duct via existing T-tube tract; billing note: applicable if a T-tube was left in place at the original cholecystectomy and percutaneous extraction is performed through that tract.
🏷️ Modifier Reference
| Modifier | Name | When to Apply |
|---|---|---|
| -59 | Distinct Service | Apply when an ERCP-related code and a separately identifiable procedure are performed at different anatomic sites or sessions and NCCI edits require it. |
| -51 | Multiple Procedures | Apply when more than one reportable procedure (e.g., sphincterotomy plus stone removal, per payer rules) is performed in the same session and both are separately payable. |
| -52 | Reduced Services | Apply if the ERCP or stone extraction is completed but a planned component (e.g., full duct clearance) is not achieved due to anatomic difficulty. |
| -53 | Discontinued Procedure | Apply if the ERCP is terminated after initiation due to patient risk or complication before completion. |
| -58 | Staged Procedure | Apply when a planned staged approach is used (e.g., stent placement first, extraction in a later session) during the postoperative period. |
| -78 | Return to OR/Procedure Suite | Apply when the patient returns unplanned for a related procedure (e.g., repeat ERCP for incomplete clearance) during the global period. |
| -79 | Unrelated Procedure | Apply when an unrelated procedure is performed during the global period of a prior related service. |
| -25 | Significant, Separately Identifiable E/M | Apply when a significant E/M service is documented and billed on the same day as the ERCP. |
| -24 | Unrelated E/M During Global Period | Apply when an E/M visit unrelated to the ERCP/stone extraction occurs during a global period. |
NCCI Bundling Considerations
Diagnostic ERCP (43260) is bundled into any therapeutic ERCP code performed in the same session (e.g., 43264, 43265, 43268) and should not be separately reported without a valid, documented modifier justification.
🔬 ICD-10-PCS Crosswalk
- 0FC98ZZ — Extirpation of matter from common bile duct, via natural or artificial opening endoscopic; used when ERCP-based stone extraction is the inpatient procedure performed.
- 0FC97ZZ — Extirpation of matter from common bile duct, percutaneous endoscopic approach; used for T-tube-tract or percutaneous transhepatic stone retrieval.
- 0F798DZ — Dilation of common bile duct with intraluminal device, via natural or artificial opening endoscopic; used when a biliary stent is placed to manage obstruction from the retained stone.
💊 Coding Scenarios and Examples
Example 1
Clinical Scenario: Patient with cholecystectomy six weeks prior is admitted with jaundice and elevated liver enzymes. ERCP confirms a retained common bile duct stone, which is removed via sphincterotomy and stone extraction without complication.
| Field | Code | Rationale |
|---|---|---|
| CPT | 43264-59 | Therapeutic ERCP stone extraction is the primary billable procedure; modifier applied only if a bundled diagnostic component needs separate reporting per payer edit. |
| PDx | K91.86 | Retained stone confirmed after prior cholecystectomy is the documented reason for admission. |
Tip
Sequence K91.86 as principal diagnosis since it is the confirmed reason for the admission and the focus of treatment. No additional CC/MCC secondary diagnosis is present, so this case falls to DRG 395.
Example 2
Clinical Scenario: Similar presentation, but the retained stone has caused ascending cholangitis with fever and bacteremia, requiring IV antibiotics in addition to ERCP-guided stone removal and stent placement.
| Field | Code | Rationale |
|---|---|---|
| CPT | 43264-51 | Stone extraction reported as the primary therapeutic procedure. |
| CPT 2 | 43268 | Stent placement performed in the same session to ensure drainage. |
| PDx | K91.86 | Underlying reason the biliary obstruction/infection occurred. |
Tip
Code the cholangitis (K83.0) as a secondary diagnosis — its documentation as an MCC-qualifying complication is what would move this case to DRG 393 rather than 395. Confirm the provider documents “ascending cholangitis” explicitly, not just “elevated liver enzymes,” to support MCC capture.
Example 3
Clinical Scenario: Patient with a T-tube left in place after cholecystectomy returns for scheduled percutaneous extraction of a known retained stone through the existing tract; procedure completed without incident.
| Field | Code | Rationale |
|---|---|---|
| CPT | 47425-58 | Staged/planned procedure performed via the existing T-tube tract as part of the postoperative treatment plan. |
| PDx | K91.86 | Retained stone remains the documented diagnosis driving the planned procedure. |
Tip
⚠️ Coding Pitfalls and Tips
- Pitfall 1: Defaulting to a K80 cholelithiasis code because the clinical language says “gallstone” without checking cholecystectomy history; Tips: Always verify gallbladder status in the H&P/problem list before code selection.
- Pitfall 2: Reporting K91.8 or K91 alone; Tips: These are non-billable parent/category codes — K91.86 (or another 5th-character K91.8x code) must be assigned.
- Pitfall 3: Missing a secondary diagnosis for cholangitis, pancreatitis, or hemorrhage that would qualify as CC/MCC; Tips: Review the full ERCP and progress notes, not just the admitting diagnosis, for complication documentation.
- Pitfall 4: Reporting diagnostic ERCP (43260) separately alongside a therapeutic ERCP code in the same session; Tips: Diagnostic ERCP is bundled — don’t unbundle without a payer-recognized modifier justification.
- Pitfall 5: Assuming K91.86 maps to MDC 07 because it’s biliary in nature; Tips: Confirm grouper output — this code lands in MDC 06 (DRGs 393–395), a frequent source of DRG-assignment confusion.
- Pitfall 6: Coding K91.86 for a stone found during the original cholecystectomy admission (i.e., before the surgery is complete); Tips: K91.86 applies to stones identified after the cholecystectomy has already been performed, not intraoperative findings during the index surgery.
📚 Sources
1. Centers for Medicare & Medicaid Services / National Center for Health Statistics. *ICD-10-CM FY2026 Tabular List and Official Guidelines for Coding and Reporting.* CMS/NCHS; 2025. 2. Centers for Medicare & Medicaid Services. *ICD-10-CM/PCS MS-DRG v43.0 Definitions Manual.* CMS; 2025. 3. AAPC. *ICD-10-CM Professional Codebook, 2026 Edition.* AAPC; 2026. 4. icd10data.com. *K91.86 — Retained cholelithiasis following cholecystectomy.* 2026 edition.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.