ICD-10 code K82.1: Hydrops of gallbladder – FY 2026 guide

Key Takeaways

ICD-10 code K82.1 (Hydrops of gallbladder) is a billable, HIPAA-valid diagnosis code effective October 1, 2025 for FY 2026.

Applicable To notes include mucocele of gallbladder, making K82.1 the correct code for both clinical presentations.

K82.1 sits within parent category K82 (Other diseases of gallbladder) under block K80-K87. Coders must distinguish it from K82.0 (obstruction) and K80.x (cholelithiasis) to avoid claim errors.

K82 also includes K82.A, a subcategory for gallbladder gangrene and perforation occurring specifically in cholecystitis, both of which require the cholecystitis code first.

Practice management software like Pabau supports accurate ICD-10 diagnosis capture and billing workflow documentation for gallbladder conditions.

Gallbladder hydrops accounts for a small but clinically significant subset of biliary tract conditions. ICD-10 code K82.1 is the specific, billable code for hydrops of the gallbladder, and it covers more ground than its short description suggests.

Coders who miss the Applicable To notes, or the differential between K82.1 and K82.0, routinely pick the wrong code, and that mismatch surfaces later as a claim denial or a payer audit. The sections below, sourced from CMS ICD-10-CM official code files and the CDC/NCHS ICD-10-CM web tool, walk through where K82.1 fits in the hierarchy and how to code it correctly.

ICD-10 code K82.1: definition and code details

ICD-10 code K82.1 identifies a diagnosis of hydrops of the gallbladder. It is a billable, specific ICD-10-CM code, meaning it can be submitted directly on claims for reimbursement. No further specificity is required. The FY 2026 edition of this code became effective on October 1, 2025 and remains valid through September 30, 2026.

Regarding HIPAA-covered electronic transactions: K82.1’s HIPAA validity confirms the code is accepted for electronic claim submission under standard transactions. It does not guarantee Medicare or Medicaid coverage for any specific service or procedure. Coverage determinations depend on medical necessity, local coverage decisions (LCDs), and individual payer policies.

Applicable to: mucocele of gallbladder

The ICD-10-CM tabular list includes an Applicable To note under K82.1 that directs coders to use this code for mucocele of gallbladder as well. This note is not optional guidance: it means K82.1 is the correct and complete code for both presentations.

• Hydrops of gallbladder: The gallbladder becomes distended with clear mucoid fluid following cystic duct obstruction. The bile is reabsorbed and replaced by mucus secreted by the gallbladder wall.
• Mucocele of gallbladder: The same pathophysiological process described using an alternate clinical term. Both terms refer to cystic duct blockage producing a fluid-filled, enlarged gallbladder.

Clinicians and coders sometimes document one term while meaning the other. The Applicable To note resolves any ambiguity: if the chart says “mucocele of gallbladder,” K82.1 is the correct code. No alternative code exists for this presentation within the ICD-10-CM system.

Clinical description: hydrops of the gallbladder

Hydrops of the gallbladder occurs when the cystic duct becomes obstructed, most commonly by a gallstone (cholelithiasis, coded K80.x), and bile can no longer drain from the gallbladder. Over time, existing bile is reabsorbed and the gallbladder fills with clear or white mucoid fluid secreted by its own epithelial lining. The result is a significantly distended, non-functioning gallbladder.

Patients often first raise right upper quadrant pain during a general practice visit, well before imaging confirms hydrops, so the diagnosis frequently surfaces through a GI referral rather than a same-day surgical admission.

Key clinical features coders may encounter in the medical record include:

• Right upper quadrant pain or a palpable mass
• A palpable gallbladder on examination
• Imaging findings of gallbladder enlargement with anechoic contents on ultrasound

Fever is typically absent in uncomplicated hydrops, which is what distinguishes it from acute cholecystitis. When infection supervenes, the condition progresses to empyema of the gallbladder, which carries a separate code.

Nursing teams monitoring a suspected cholecystitis admission often work from a structured nursing care plan that tracks fever trends and pain response while imaging is pending.

Acalculous hydrops (hydrops without gallstones) occurs less frequently and may be associated with prolonged fasting, total parenteral nutrition, or critical illness. The code K82.1 applies in both calculous and acalculous presentations. Good clinical documentation of the underlying etiology supports appropriate sequencing decisions when an additional code for the cause (such as K80.x) is warranted.

Rapid weight loss is also a recognized gallstone risk factor, since fast fat breakdown raises cholesterol saturation in bile. Practices running structured weight loss programs should stay alert to new right upper quadrant symptoms in patients losing weight quickly.

ICD-10-CM code hierarchy for K82.1

Understanding where K82.1 sits within the broader ICD-10-CM biliary tract codes (K80-K87) helps coders navigate related conditions and avoid selection errors. The full hierarchy runs from chapter level down to the specific billable code.

The K80-K87 block is one of the most actively coded biliary sections in outpatient and inpatient settings. For GI practices and surgical centers, understanding the full block structure prevents confusion between gallstone codes (K80), cholecystitis codes (K81), and other gallbladder disease codes (K82).

Accurate selection at the K82.x level, including K82.1, depends on reading chart documentation carefully for the specific condition rather than defaulting to an unspecified code.

The block’s final category, K87, catches gallbladder and biliary disorders that stem from a disease classified elsewhere, worth checking before defaulting to K82.8. Neighboring digestive-system chapters follow the same logic: K67 covers peritoneal disorders that arise from an infectious disease rather than a standalone peritoneal condition.

Related ICD-10 codes in the K82 category (other diseases of gallbladder)

K82 covers conditions that fall outside cholelithiasis (K80) and cholecystitis (K81). The table below lists every code in the category, including the K82.A subcategory for gangrene and perforation that occur specifically in cholecystitis, and when each applies.

For a broader view of ICD-10-CM diagnostic codes across specialties, the AAPC Codify ICD-10-CM lookup provides keyword and code range search. A gallbladder mass is not automatically a K82 code either: a confirmed malignancy is coded to C23, not any code in this category.

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Differential coding: when to use K82.1 vs related codes

This is where most coding errors with K82.1 occur. The distinction between K82.1 and its near neighbors is a documentation question, not a judgment call. The chart must support the specific code selected.

The K82.0 versus K82.1 distinction is the most common differential coding error with this code family. K82.0 (obstruction of gallbladder) describes blockage without documented fluid accumulation. Once the clinical record confirms the gallbladder has become distended with mucoid content, the condition has progressed to K82.1 territory, and that progression must be documented, never assumed.

K82.0 also carries an Excludes1 note for obstruction of gallbladder with cholelithiasis (K80.-). When gallstones are the documented cause of the obstruction, K80.- is the code to use, not K82.0. Assigning both codes together miscodes a single documented condition as two.

Coding guidelines and billing notes for ICD-10 code K82.1

K82.1 is a diagnosis code, not a procedure code. It travels with a CPT or HCPCS procedure code when billed. The most common pairing occurs when a patient undergoes cholecystectomy (gallbladder removal) for hydrops: K82.1 supports medical necessity for the procedure, alongside any applicable cholelithiasis code.

Principal vs secondary diagnosis sequencing

When hydrops of the gallbladder is the primary reason for a visit or admission, sequence K82.1 first. If it is discovered incidentally during workup for another condition, sequence the primary condition first and list K82.1 as a secondary diagnosis.

Per the ICD-10-CM Official Guidelines for Coding and Reporting, maintained jointly by CMS and NCHS, sequencing follows the reason for the encounter, not the severity of findings.

Workflow tools that link ICD-10 codes to specific encounter reasons help practices consistently apply this sequencing logic across providers.

Documentation requirements

For K82.1 to hold up on audit, the medical record should support all of the following:

• A documented diagnosis of hydrops of gallbladder or mucocele of gallbladder (either term is acceptable)
• Clinical or imaging findings consistent with gallbladder distension and mucoid fluid accumulation
• Provider attestation of the diagnosis (not solely inferred from imaging by the coder)
• Etiology noted where known (gallstones, acalculous origin, or other cause), to support additional codes if indicated

Well-structured digital intake forms and encounter documentation tools reduce the risk of incomplete records reaching the billing team. For complex multi-diagnosis encounters, consult your coding compliance team before final submission. The HIPAA compliance requirements for medical offices also apply to documentation retention and access controls for these records.

Cholecystectomy context

K82.1 is a recognized surgical indication. Cholecystectomy, typically laparoscopic, is the definitive treatment for symptomatic gallbladder hydrops. When a patient proceeds to surgery, ICD-10 code K82.1 appears on the operative claim as a supporting diagnosis code, and the relevant K80.x code joins it if gallstones caused the hydrops.

Laparoscopic cholecystectomy itself is billed under CPT 47562 when performed without cholangiography, or CPT 47563 when an intraoperative cholangiogram is added.

Anesthesia for the procedure is coded and billed separately from the surgical CPT code. Surgeons sometimes infiltrate the port sites with a local anesthetic such as mepivacaine, HCPCS code J0670, to manage postoperative pain.

Index references for ICD-10 code K82.1

The ICD-10-CM alphabetic index provides two main entry paths to K82.1. Knowing these helps coders locate the code quickly when working from clinical terminology in the chart rather than from the code itself.

• Hydrops, gallbladder → K82.1
• Mucocele, gallbladder → K82.1

Both index routes arrive at the same code, confirming the Applicable To relationship between the two clinical terms. When searching the ICD-10-CM alphabetic index for gallbladder conditions, always verify the code in the tabular list before assigning it.

The alphabetic index is a starting point, not the final authority. The tabular list contains instructional notes, including Applicable To, Excludes1, and Excludes2 notes, that do not appear in the index.

The ICD-10-CM tabular list entry for K82.1 itself contains no Excludes notes, meaning there are no mandatory exclusions specific to hydrops.

The parent K82 category does carry two Excludes1 notes worth knowing. Nonvisualization of gallbladder (R93.2) and postcholecystectomy syndrome (K91.5) are both excluded from the entire K82 category and must be coded separately rather than folded into a K82.x code. Verified via the CDC/NCHS ICD-10-CM web tool.

How Pabau supports gallbladder and biliary diagnosis coding

Accurate ICD-10 code K82.1 capture starts at the point of care. Pabau’s claims management software lets providers attach ICD-10 diagnosis codes directly to encounter records, reducing transcription errors between clinical documentation and billing. For practices handling GI or surgical cases, this means K82.1 and its companion codes travel with the encounter from chart to claim without manual re-entry.

Practices using structured medical documentation workflows see fewer audit flags because the diagnostic basis for each encounter is captured at the time of service. Combined with Pabau’s automated billing workflows, this creates a defensible documentation trail from diagnosis to reimbursement.

For practices exploring broader practice management software with integrated ICD-10 coding support, Pabau’s platform handles multi-specialty documentation alongside billing, scheduling, and compliance workflows.

Conclusion

Gallbladder coding errors cluster around two failure points: not knowing the Applicable To notes (mucocele maps to K82.1), and conflating K82.1 with K82.0 (obstruction without fluid accumulation).

ICD-10 code K82.1 is the correct, billable code when documentation confirms a distended, fluid-filled gallbladder, whether the provider calls it hydrops or mucocele. Pairing it with the appropriate K80.x code when gallstones are the documented cause completes the clinical picture for payers.

For practices looking to reduce diagnosis-to-claim errors across biliary and GI encounters, Pabau captures ICD-10 codes at the point of care and links them to billing workflows automatically. To see how it works in a live setup, book a demo with the Pabau team.

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