Ambulatory Care: Benefits, Services, and What to Expect

Ambulatory care is all about healthcare services you get without having to stay overnight in a hospital. Think regular doctor visits, urgent care for a sudden fever, lab tests, physical therapy, dialysis, seeing specialists, and even a bunch of same-day surgeries. If you’re on a medical coding or billing team, ambulatory care isn’t just about labeling something as “outpatient.” You have to know where and how each service happens, since that shapes the place-of-service (POS) code, the type of claim, the right CPT or HCPCS codes, how you pick ICD-10-CM diagnoses, which modifiers to use, what needs pre-authorization, and whether you bill separately for the professional side and the facility.

According to the National Library of Medicine, ambulatory care is healthcare that doesn’t need a hospital admission. You see it at doctors’ offices, clinics, outpatient units in hospitals, surgery centers, and dialysis clinics. This guide breaks down what ambulatory care actually means, where you’ll find it, what kinds of services and benefits it brings, and what both patients and organizations should expect. You’ll also find a look at key coding and billing issues for 2026—how to tackle CPT, HCPCS, ICD-10-CM, POS codes, and typical billing rules.

What Is Ambulatory Care?

Ambulatory care is healthcare you get without being admitted to the hospital. You might go in for a checkup, some tests, treatment, or even a procedure, but you’ll head home the same day. This kind of care covers everything from a quick blood pressure check to a complicated surgery that uses anesthesia and needs some monitoring afterward.

What really defines ambulatory care isn’t how simple or complex the service is—it’s whether you get admitted to the hospital and where you actually receive the care.

Common examples of ambulatory care include:

• Primary care visits
• Specialist consultations
• Preventive examinations
• Urgent care
• Diagnostic testing
• Laboratory services
• Imaging
• Behavioral health services
• Physical and occupational therapy
• Infusions and injections
• Dialysis
• Outpatient procedures
• Ambulatory surgery
• Chronic disease management
• Remote monitoring and selected telehealth services

In simple terms, ambulatory care refers to healthcare that does not require an inpatient stay, even when the service itself is complex or involves a surgical procedure.

What Does Ambulatory Mean in Medical Terms?

The term ambulatory can have different meanings depending on the clinical or administrative context. In healthcare, it may describe the type of care being provided or the patient’s ability to walk or move around.

Ambulatory as a Type of Healthcare

In medical billing and healthcare conversations, “ambulatory” just means care given without admitting the patient to the hospital. So, if you see a note that says a procedure happened in an ambulatory setting, that usually means the person got treated as an outpatient—they weren’t admitted for a hospital stay.

When the Patient Is Ambulatory

When a clinical note states that a patient is ambulatory, it usually means the patient is able to walk or move around independently or with assistance.

That statement alone does not justify assigning a diagnosis code. If the documentation identifies a mobility or gait problem that affects the patient’s care, an appropriate ICD-10-CM code may be reported when supported by the documentation.

Examples include:

The word ambulatory should not be used by itself as the reason for assigning one of these codes. The medical record must document the underlying condition and support the selected diagnosis code.

What Is an Ambulatory Setting in Healthcare?

An ambulatory setting in healthcare is a location where patients receive healthcare without being admitted as hospital inpatients.

AHRQ includes medical offices, clinics, ambulatory surgery centers, hospital outpatient departments, and dialysis centers within the ambulatory-care environment.

From a billing perspective, the exact type of setting matters because “ambulatory” is not itself a Place of Service code.

Common professional-claim POS codes include:

CMS maintains these two-digit POS codes for professional claims. For example, POS 11 represents an office, POS 20 an urgent care facility, POS 22 an on-campus hospital outpatient department, and POS 24 a freestanding ASC.

Correct POS reporting is important because site of service may affect reimbursement, benefit processing, credentialing requirements, and payer edits.

Ambulatory Care vs. Outpatient Care: Is There a Difference?

The terms ambulatory care and outpatient care are frequently used interchangeably.

Both generally describe services provided without an inpatient admission.

There can, however, be differences in how organizations use the terms.

“Outpatient” is often used as a formal patient-status or billing concept, particularly in hospitals. “Ambulatory care” is broader and may describe the full healthcare delivery model that includes physician offices, specialty clinics, independent centers, rehabilitation, urgent care, diagnostic facilities, and same-day surgery.

For coding purposes, the important questions are not whether a facility calls itself “ambulatory,” but:

• What was the patient’s official status?
• Where was the service performed?
• Who performed the service?
• What type of claim is being submitted?
• What CPT/HCPCS code describes the service?
• What diagnosis or reason for the encounter is supported?
• Which payer rules apply?

Major Benefits of Ambulatory Care

Ambulatory care has expanded as more evaluation, diagnostic, treatment, and procedural services can safely be provided without inpatient hospitalization.

1. Same-Day Care and Discharge

Patients can often receive evaluation, treatment, or surgery and return home the same day.

This can reduce disruption to the patient’s normal routine while allowing inpatient resources to remain available for patients who need hospital-level care.

2. Easier Access to Routine and Preventive Care

Physician offices, community clinics, FQHCs, urgent care facilities, and other ambulatory care facilities can provide convenient access for:

• Preventive services
• Immunizations
• Chronic disease monitoring
• Medication management
• Screening
• Follow-up care

3. Better Support for Chronic Conditions

Conditions such as hypertension, diabetes, asthma, heart disease, and chronic musculoskeletal disorders often require repeated outpatient monitoring rather than hospitalization.

A well-organized ambulatory care practice can provide continuing assessment, medication management, laboratory monitoring, education, referrals, and care coordination.

4. Potentially Lower Resource Use

Many services can require fewer facility resources when safely performed in an ambulatory environment rather than through an inpatient admission.

This does not mean that every service is less expensive in every outpatient setting. Hospital outpatient departments, physician offices, ASCs, and independent facilities may operate under different payment systems and patient cost-sharing structures.

5. Greater Opportunity for Coordinated Longitudinal Care

Primary care and specialty ambulatory practices can follow patients over months or years, which supports management of changing risk factors and chronic conditions.

For Medicare, CMS continues to recognize the complexity of longitudinal office/outpatient care through HCPCS code G2211 when its requirements are met. CMS confirms that G2211 may be reported with the office/outpatient E/M family 99202–99205 and 99211–99215 under applicable rules.

Common Ambulatory Care Services and CPT/HCPCS Code Families

There is no single list of all ambulatory care CPT codes.

CPT 2026 contains more than 11,500 codes overall, and ambulatory facilities may provide services across dozens of specialties.

Therefore, a claim should never receive a CPT code simply because the patient was treated in an ambulatory setting.

The code must represent the specific documented service performed.

The following table is a practical reference to frequently encountered ambulatory categories. It is not an exhaustive code list.

The AMA made the CPT 2026 Category I code set effective January 1, 2026 and added new digital-health codes, including shorter-duration remote monitoring services. Medicare coverage and payment requirements still must be checked separately from the existence of a CPT code.

Important Distinction: A CPT Code Does Not Guarantee Payment

A valid CPT code tells the payer what service was performed. It does not, by itself, establish:

• Medical necessity
• Coverage
• Prior authorization
• Correct POS
• Network eligibility
• Frequency limits
• Proper modifier use
• Payment amount

Coverage is determined by the applicable payer contract, benefit plan, Medicare rule, Medicaid program, National Coverage Determination, Local Coverage Determination, or other policy.

Medicare Preventive Ambulatory Services

Preventive services are common in ambulatory practices, but Medicare billing should not be confused with commercial preventive physical billing.

CMS identifies:

• G0402 for the Initial Preventive Physical Examination
• G0438 for the initial Medicare Annual Wellness Visit
• G0439 for subsequent Annual Wellness Visits

CMS also states that there is no single required diagnosis code for an AWV; the diagnosis reported should be consistent with the patient’s encounter. When a significant, separately identifiable medically necessary problem-oriented E/M service is performed at the same encounter, an appropriate 99202–99205 or 99211–99215 service may potentially be reported with modifier 25 when all requirements are satisfied.

Do not automatically substitute preventive CPT codes 99381–99397 for Medicare AWV or IPPE services. Those services represent different benefit and coding concepts.

ICD-10-CM and DX Codes for Ambulatory Care

Another common question is:

“What is the ambulatory care diagnosis code?”

There is no single ICD-10-CM code for ambulatory care.

The diagnosis code represents why the patient received the service, not the fact that it occurred in an ambulatory setting.

“DX code” in everyday billing terminology normally refers to the ICD-10-CM diagnosis code reported on the claim.

Common ICD-10-CM Examples Seen in Ambulatory Care

Depending on documentation, an ambulatory practice may encounter codes such as:

These examples are intended to show the range of diagnosis categories encountered in ambulatory practice. They are not a substitute for indexing the documented diagnosis and confirming the code in the current ICD-10-CM Tabular List.

The CDC provides the official ICD-10-CM browser and release files, while the official coding guidelines require coders to use the Alphabetic Index and then verify the selected code in the Tabular List.

The Most Important ICD-10-CM Rule for Ambulatory Outpatient Coding

One of the biggest differences between inpatient and outpatient diagnosis coding involves uncertain diagnoses.

For outpatient services, do not code a condition documented only as:

• Probable
• Suspected
• Questionable
• Rule out
• Compatible with
• Consistent with
• Working diagnosis

Instead, code to the highest degree of certainty known for that encounter, such as the documented sign, symptom, abnormal finding, or other reason for the visit.

The FY 2026 ICD-10-CM Official Guidelines specifically state that the inpatient uncertain-diagnosis rule does not apply to outpatient encounters.

Example

A patient visits an urgent care center with cough, fever, and fatigue. The provider documents:

Suspected pneumonia; chest X-ray ordered.

If pneumonia is not confirmed at the time applicable coding is completed, the coder should not simply assign a pneumonia diagnosis because it was “suspected.” The documented signs and symptoms should be evaluated under the outpatient guidelines.

If the definitive diagnosis later becomes available in an interpreted diagnostic report and the official rules permit its use for that encounter, coding should follow the applicable outpatient diagnostic-service guidance.

First-Listed Diagnosis in Ambulatory Care

Hospital outpatient and physician-office coding uses the term first-listed diagnosis rather than the inpatient concept of principal diagnosis.

Generally, the first-listed condition is the diagnosis, condition, problem, or reason for the encounter chiefly responsible for the services provided, subject to ICD-10-CM conventions and chapter-specific instructions.

For same-day outpatient surgery, the FY 2026 guidelines instruct coders to report the reason for surgery as the first-listed diagnosis, even when the planned surgery is not performed because of a contraindication.

Coders should also report additional conditions when they coexist at the encounter and require or affect evaluation, treatment, management, or care. A historical diagnosis that has no relevance to the current service should not automatically appear on every claim.

Ambulatory Surgery Center Coding and Billing

An ambulatory surgical center is a specific type of ambulatory facility, not simply another name for an outpatient clinic.

CMS defines POS 24 as an Ambulatory Surgical Center—a freestanding facility where surgical and diagnostic services are delivered on an ambulatory basis.

Medicare-certified ASCs provide surgical services to patients who are not expected to require hospitalization. CMS states that ASC participation is limited to entities providing surgical services where the expected duration generally does not extend beyond 24 hours after admission.

Not Every Surgical CPT Code Is Payable in an ASC

This is a major billing issue.

CMS maintains an ASC Covered Procedures List (CPL) and related payment files. A procedure being valid in CPT does not mean Medicare automatically pays the ASC facility for performing it.

For CY 2026, CMS made substantial revisions to the ASC Covered Procedures List and added hundreds of procedures under revised criteria. Because the list and payment indicators can be updated, ASC billers should use the CMS file applicable to the exact date of service.

Codes commonly encountered in ambulatory surgery may include procedures such as colonoscopy, cataract extraction, arthroscopy, pain procedures, endoscopy, dermatologic surgery, and other specialty services. The correct CPT/HCPCS code must be selected from the specific operative documentation and then checked against payer and ASC coverage rules.

Professional vs. Facility Billing

An ASC encounter can generate more than one claim.

For example:

• The ASC may bill its facility service.
• The surgeon may bill professional services.
• An anesthesiology professional may submit a separate claim.
• Pathology or other professional components may be billed separately when appropriate.

CMS states that ASC facility payment is limited to covered surgical procedures and qualifying ancillary services, while physician and certain other professional services may be separately payable under Medicare Part B rules.

This distinction is essential when reviewing duplicate-payment edits or explaining a patient’s Explanation of Benefits.

Hospital Outpatient Billing Is Different From Physician Office Billing

A hospital outpatient department may involve both institutional and professional reimbursement.

Hospitals commonly report outpatient facility services through institutional claim processes, while physicians and other eligible practitioners submit professional services separately when appropriate.

CMS identifies CMS-1500/837P as the professional claim formats used by non-institutional providers and suppliers.

Hospital outpatient facility claims operate under institutional billing rules and may be paid under the Hospital Outpatient Prospective Payment System (OPPS), fee schedules, or another applicable methodology.

Therefore, a clinic operating as a hospital provider-based department may have a different billing structure than an independent physician office, even when the clinical encounter appears similar to the patient.

FQHC Ambulatory Billing

Federally Qualified Health Centers use another distinct payment structure.

For 2026 Medicare FQHC billing, CMS identifies payment-specific codes including:

• G0466 — new-patient qualifying FQHC visit
• G0467 — established-patient qualifying FQHC visit
• G0468 — qualifying FQHC IPPE/AWV visit
• G0469/G0470 — applicable mental-health FQHC visit categories

CMS instructs FQHCs to report qualifying encounter information under its PPS billing structure rather than treating the claim exactly like a standard POS 11 physician-office claim.

Practices should therefore avoid assuming that a CPT code generates identical payment across an independent office, HOPD, ASC, FQHC, and RHC.

What Happens During an Ambulatory Care Visit?

Although workflow varies by specialty, most ambulatory encounters follow a similar sequence.

Before the Visit

The front-end revenue-cycle team may need to confirm:

• Patient demographics
• Insurance eligibility
• Benefit coverage
• Referral requirements
• Network status
• Prior authorization
• Medical-necessity criteria
• Scheduled services
• Correct rendering and billing provider information

Many avoidable denials begin before the patient reaches the examination room.

Registration and Clinical Intake

The team may document:

• Chief complaint
• Vital signs
• Medication list
• Allergies
• Relevant medical history
• Screening information
• Reason for the encounter

Clinical staff should avoid selecting diagnoses solely to satisfy billing requirements. Diagnosis reporting should flow from provider-supported documentation and applicable coding rules.

Provider Evaluation

The physician or qualified healthcare professional evaluates the patient and documents the assessment and plan.

For office/outpatient E/M services, 99202–99205 and 99211–99215 remain central code families. Selection should follow the current CPT rules for medical decision-making or total time when applicable rather than relying on outdated documentation formulas. CMS continues to recognize these code families in its current E/M guidance.

Diagnostic or Therapeutic Services

The patient may also receive:

• Laboratory testing
• Imaging
• ECG
• Injections
• Infusions
• Minor procedures
• Wound care
• Therapy
• Behavioral health services

These services should be separately reported only when coding and payer rules allow.

Checkout and Follow-Up

The patient may receive:

• Medication instructions
• Post-procedure instructions
• Referrals
• Follow-up appointments
• Test orders
• Warning signs requiring urgent evaluation
• Preventive-care recommendations

Accurate capture of the final assessment and services performed supports both continuity of care and cleaner claims.

A Practical Ambulatory Care Billing Workflow

A reliable ambulatory care practice should connect clinical documentation and billing rather than treating coding as an isolated back-office task.

Step 1: Identify the Exact Setting

Confirm whether the encounter took place in:

• POS 11 office
• POS 20 urgent care
• POS 19/22 hospital outpatient department
• POS 24 ASC
• FQHC
• RHC
• Another ambulatory facility

Step 2: Identify the Service Performed

Select the CPT or HCPCS code that accurately represents the service documented.

Do not select a code based solely on:

• The scheduled appointment type
• A superbill default
• The patient’s previous visit
• A payer’s desired reimbursement
• A problem-list diagnosis

Step 3: Determine the First-Listed Diagnosis

Identify the condition or reason chiefly responsible for the outpatient service, subject to ICD-10-CM conventions.

Step 4: Add Relevant Secondary Diagnoses

Report coexisting conditions when they affect the care, treatment, evaluation, or management provided during the encounter.

Step 5: Link Diagnoses to Procedures

Each CPT/HCPCS line should point to the diagnosis or diagnoses supporting that specific service where the claim format requires diagnosis pointers.

A patient may have six diagnoses in the chart, but that does not mean all six support every service line.

Step 6: Review Modifiers

Common modifiers encountered in ambulatory billing may include:

• 25 — separately identifiable E/M on the same day as another qualifying service
• 26 — professional component, when applicable
• TC — technical component, when applicable
• 59 — distinct procedural service when requirements are met
• XE, XP, XS, XU — more specific subset modifiers where appropriate
• RT/LT — laterality when required by the code or payer
• Therapy modifiers such as GP, GO, or GN when applicable

Modifier use must be supported by the clinical circumstances. A modifier should never be added merely to force a claim through an edit.

Step 7: Run Coding Edits

CMS NCCI Procedure-to-Procedure edits identify CPT/HCPCS combinations that generally should not be reported together unless circumstances and an appropriate modifier support separate reporting.

CMS also maintains Medically Unlikely Edits for units of service.

These files are updated quarterly. The Medicare Q3 2026 NCCI edits became effective July 1, 2026.

Step 8: Submit and Track the Claim

The billing team should monitor:

• Initial acceptance
• Clearinghouse rejection
• Payer rejection
• Claim adjudication
• Denial reason
• Patient responsibility
• Corrected claim requirements
• Appeal deadlines

Common Ambulatory Care Billing Problems

Wrong Place of Service

Billing POS 11 when the service actually occurred in an HOPD or ASC can create reimbursement and compliance problems.

Unsupported Diagnosis Coding

Using a chronic diagnosis that was not evaluated or relevant to the encounter simply to support medical necessity can be problematic.

Coding a “Rule-Out” Condition

This is a frequent outpatient ICD-10-CM error. Outpatient coders generally code signs, symptoms, or other documented reasons for the encounter when the diagnosis remains uncertain.

Incorrect Modifier 25 Use

Modifier 25 is not justified simply because an E/M code and procedure occurred on the same date.

The E/M work must meet the applicable requirements for a significant, separately identifiable service.

Missing Authorization

The CPT and ICD-10-CM coding may be correct, but the payer can still deny the claim if a required authorization was not obtained.

Unbundling Services

Reporting separately services that are included in a more comprehensive code can trigger NCCI edits or payer audits.

Excessive Units

Incorrect units of service may trigger MUEs or payer-specific edits.

Using an Outdated Code Set

This is particularly important around January 1 CPT updates and October 1 ICD-10-CM updates.

For example, a September 2026 encounter and an October 2026 encounter may require different ICD-10-CM release files even though both occur in calendar year 2026.

Practical Coding Examples

Example 1: Established Patient With Hypertension

An established patient attends a primary care office for hypertension management. The provider reviews blood pressure trends, medications, adherence, relevant laboratory information, and adjusts treatment.

Potential coding framework:

• CPT: Appropriate established-patient E/M from 99211–99215 based on documented CPT selection criteria
• ICD-10-CM: I10 when supported as the condition managed
• POS: 11 if performed in a qualifying physician office
• Possible HCPCS: G2211 if Medicare requirements are independently satisfied

Do not choose the E/M level solely from the diagnosis. Hypertension does not automatically equal a particular visit level.

Example 2: Urgent Care for Cough With Pneumonia Not Confirmed

A patient presents to urgent care with cough and fever. The provider documents “rule out pneumonia” and orders imaging.

Possible framework before a definitive diagnosis is available:

• Appropriate new or established outpatient E/M
• POS 20 when the location meets the CMS urgent care definition
• Symptom diagnosis code(s), such as R05.9 when supported
• Diagnostic test code as applicable

Do not code pneumonia merely because it is being ruled out.

Example 3: Medicare Annual Wellness Visit Plus Problem-Oriented Care

A Medicare patient receives a subsequent AWV. During the same encounter, the clinician separately evaluates a worsening chronic condition and performs medically necessary problem-oriented management beyond the AWV requirements.

Potential framework:

• G0439 for the subsequent AWV
• Appropriate office/outpatient E/M when separately supported
• Modifier 25 on the E/M where required
• ICD-10-CM diagnosis supporting the separate medical problem

CMS permits additional payment for a significant, separately identifiable medically necessary E/M service with an AWV when the requirements are satisfied.

Example 4: Outpatient Same-Day Surgery

A patient arrives for a scheduled ambulatory surgical procedure.

The coding team should:

1. Review the operative documentation.
2. Assign the appropriate CPT/HCPCS procedure.
3. Report the reason for surgery as the first-listed diagnosis according to outpatient guidance.
4. Verify the facility setting and POS.
5. Confirm that the procedure is covered in the ASC if Medicare ASC facility payment is expected.
6. Check applicable modifiers and NCCI edits.

The same-day nature of the case does not create a special generic “ambulatory surgery CPT code.”

Documentation Requirements for a Clean Ambulatory Claim

Good ambulatory documentation should make it possible for another qualified reviewer to understand:

• Why the patient was seen
• What conditions were assessed
• What work was performed
• What tests or procedures were ordered or completed
• The treatment plan
• The medical necessity of services
• Relevant medication management
• Any separately identifiable services
• The provider responsible for the service
• Where and when the service occurred

For E/M coding, avoid adding documentation merely to increase note length. The record should reflect the medically appropriate work performed.

For ICD-10-CM, the official guidelines emphasize that accurate coding depends on complete, consistent documentation and collaboration between providers and coders.

How Ambulatory Practices Can Improve Revenue-Cycle Accuracy

An ambulatory care practice can reduce preventable billing problems by building controls around the entire encounter rather than relying only on claim scrubbing.

Useful controls include:

• Eligibility verification before the visit
• Prior-authorization tracking
• Accurate location mapping
• Current CPT, HCPCS, and ICD-10-CM files
• Provider-specific coding education
• Diagnosis-to-procedure linkage reviews
• Automated NCCI checking
• Modifier audits
• Denial trend analysis
• Documentation feedback
• Regular payer-policy review
• Quarterly coding-edit updates

Organizations operating multiple locations should pay particular attention to POS mapping. A health system may have independent offices, provider-based departments, urgent care centers, ASCs, and FQHC locations that look similar operationally but require different billing rules.

Conclusion

Ambulatory care covers a wide range of outpatient services, from preventive and primary care to diagnostics, specialty care, therapy, and ambulatory surgery. Accurate ambulatory billing and coding requires the correct CPT, HCPCS, ICD-10-CM, place of service, modifiers, and payer-specific requirements.

For 2026 dates of service, always verify the applicable code-set version and current CMS and payer guidance. This helps support accurate claims, reduce denials, and maintain compliant ambulatory billing practices.

Frequently Asked Questions About Ambulatory Care

What is ambulatory care?

Ambulatory care is healthcare provided without inpatient hospital admission. It includes services delivered in physician offices, clinics, hospital outpatient departments, ambulatory surgery centers, dialysis facilities, and other outpatient environments.

What does ambulatory mean in medical terms?

It can mean either that a patient is able to walk or that healthcare is being delivered on an outpatient basis. The intended meaning depends on the clinical context.

What does it mean when a patient is ambulatory?

When a clinical note states that a patient is ambulatory, it generally means the patient is capable of walking or moving around. That statement alone does not justify a diagnosis code for a mobility disorder.

Is ambulatory care the same as outpatient care?

The terms overlap substantially and are often used interchangeably. “Ambulatory care” may describe the broader care-delivery model, while “outpatient” is frequently used as a formal patient-status and billing term.

What are examples of ambulatory care facilities?

Examples include physician offices, independent clinics, urgent care centers, hospital outpatient departments, ambulatory surgical centers, rehabilitation facilities, dialysis centers, FQHCs, RHCs, and public health clinics.

What CPT code is used for ambulatory care?

There is no single CPT code for ambulatory care. The CPT/HCPCS code must describe the actual service, such as an E/M visit, laboratory test, procedure, therapy service, preventive service, or surgery.

What ICD-10 code is used for ambulatory care?

There is no general ICD-10-CM code for “ambulatory care.” The diagnosis code reports the condition, symptom, screening purpose, follow-up reason, or other documented reason for the encounter.

What CPT codes are commonly used for ambulatory outpatient visits?

The core office/outpatient E/M families are 99202–99205 for new patients and 99211–99215 for established patients. Other codes depend on the actual services performed.

What Place of Service code is used for ambulatory care?

It depends on the location. Common examples include POS 11 for an office, POS 20 for urgent care, POS 19 or 22 for hospital outpatient departments, and POS 24 for an ASC.

Can suspected diagnoses be coded in ambulatory care?

Generally, no. Under outpatient ICD-10-CM rules, conditions documented only as probable, suspected, questionable, rule out, or similar uncertainty terms are not coded as though confirmed. Report the documented condition, sign, symptom, abnormal finding, or other reason for the visit to the highest degree of certainty available.