R55: Syncope and collapse

The ICD-10-CM code for syncope and collapse when a transient loss of consciousness with spontaneous recovery is documented and no underlying cause has been established as the definitive diagnosis.

Billable

FY2027

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At a glance

Code Family

R55: Syncope and collapse.

Condition

Syncope

Family Specificity

R55 is a three character code with no children. There is no decimal to add and no specificity ladder inside the family.

HCC Mapping (v28)

None. Published CMS-HCC v28 category code lists do not include R55.

DRG Grouping

Principal diagnosis on the logic list for MS-DRG 312, Syncope and Collapse, in MDC 05 under the FY2027 MS-DRG v44 grouper. MS-DRG 312 is a single unsplit DRG.

Billable

Yes

Which R55 code do I assign?

R55 is a three character code with no children, which means there is no decimal to add and no specificity ladder inside the family. The decision that matters is R55 against the underlying cause once that cause is known. The Excludes1 note at R55 names most of the alternatives by code.

When documentation says…

Code

Syncope, cause not established after workup

R55

Syncope and collapse. Blackout, Fainting and Vasovagal attack are the inclusion terms printed at R55 in the FY2027 tabular. Section I.B.4 of the FY2027 Official Guidelines permits a symptom code when a related definitive diagnosis has not been established by the provider.

Vasovagal syncope

R55

Vasovagal attack is printed as an inclusion term at R55. The Alphabetic Index sub-entries for vasovagal, vasodepressor, vasomotor, cardiac and heart syncope all resolve to R55. Naming the reflex mechanism does not move the encounter off R55.

Presyncope, no loss of consciousness

R55

The FY2027 Alphabetic Index main term is printed Syncope (near) (pre-) with code R55. Near and pre are nonessential modifiers on that main term, which routes both presyncope and near syncope to R55. The tabular at R55 names neither term. Section I.B.1 of the FY2027 Official Guidelines directs coders to use both the Alphabetic Index and the Tabular List.

Syncope on standing, orthostatic vital signs recorded

I95.1

Orthostatic hypotension. The Excludes1 note at R55 names orthostatic hypotension by code. R55 and I95.1 are not reported together for the same condition.

Carotid sinus syncope

G90.01

Carotid sinus syncope. The Excludes1 note at R55 names it by code. Where carotid sinus hypersensitivity is documented as the mechanism, G90.01 replaces R55 rather than accompanying it.

Syncope explained by a documented arrhythmia

I49.5

Sick sinus syndrome, given here as one of the arrhythmia codes. Once the provider names the arrhythmia as the cause, the arrhythmia is the definitive diagnosis. R55 carries no Excludes1 note for the arrhythmia codes. The bar on reporting R55 comes from Section I.B.4 rather than from a tabular note.

Pulseless, resuscitation performed

I46.9

Cardiac arrest, cause unspecified. Cardiac arrest is not syncope. Syncope resolves without intervention. R55 carries no Excludes1 note for category I46. The separation rests on what the record says about the pulse and the resuscitation.

Tabular notes

EXCLUDES1

R55 carries a long Excludes1 note. It names cardiogenic shock (R57.0), carotid sinus syncope (G90.01), heat syncope (T67.1), neurocirculatory asthenia (F45.8), neurogenic orthostatic hypotension (G90.3), orthostatic hypotension (I95.1), postprocedural shock (T81.1-), psychogenic syncope (F48.8), shock NOS (R57.9), shock complicating or following abortion or ectopic or molar pregnancy (O00–O07, O08.3), shock complicating or following labor and delivery (O75.1), Stokes-Adams attack (I45.9) and unconsciousness NOS (the R40.2 codes). Excludes1 means the codes are not reported together for the same condition. Every entry on that list is a replacement for R55, not a companion to it. Two entries sit closest to the R55 fact pattern: I95.1 for a faint on standing and G90.01 for a faint on carotid sinus pressure. A third is easy to miss. T81.10 carries Collapse NOS during or resulting from a procedure as a printed inclusion term, which puts a periprocedural collapse outside R55. Note also what the list does not contain. There is no Excludes1 entry for convulsions in category R56, for epilepsy in category G40, for cardiac arrest in category I46 or for the arrhythmia codes. Separation from those conditions rests on provider documentation and on Section I.B.4 of the FY2027 Official Guidelines, not on a tabular exclusion.

EXCLUDES2

R55 carries no Excludes2 note of its own. Chapter 18 carries one at the chapter level and R55 inherits it. That note excludes abnormal findings on antenatal screening of mother (O28.-), certain conditions originating in the perinatal period (P04–P96), signs and symptoms of breast (N63, N64.5) and signs and symptoms classified in the body system chapters. The last clause is the one that governs syncope. Orthostatic hypotension sits in chapter 9 and carotid sinus syncope sits in chapter 6 because the classification places those signs with their body systems. Excludes2 permits dual coding where both conditions are genuinely present and clinically appropriate.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda make no addition, deletion or revision to R55. The FY2027 tabular addenda change no instructional note at R55. R55 is in the FY2027 billable code list and remains billable at three characters. One FY2027 change points to R55 from elsewhere: new code I49.82, Ventricular bigeminy, carries a Use additional note for associated symptoms such as dizziness (R42) and syncope (R55).

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

None. Published CMS-HCC v28 category code lists do not include R55.

Syncope is a symptom rather than a condition. R55 carries no v28 weight. Some chapter 18 codes do map in v28, such as R56.9, Unspecified convulsions.

The condition that risk adjusts is the cause, once the provider names it.

Where a specified arrhythmia is documented as the cause, that arrhythmia maps to HCC 238, Specified Heart Arrhythmias, under CMS-HCC v28. Published v28 code lists for HCC 238 include I44.2, I48.91 and I49.5.

CMS-HCC v28 is at full weight for payment year 2026.

MS-DRG v44 (FY2027)

R55 sits on the principal diagnosis logic list for MS-DRG 312, Syncope and Collapse, in MDC 05, diseases and disorders of the circulatory system.

MS-DRG 312 is a single unsplit DRG. It has no with CC or with MCC partner. A secondary diagnosis cannot move a syncope admission to a higher weighted partner DRG.

The same principal diagnosis list carries I95.1, I95.2, I95.3 and I95.81. Reporting orthostatic hypotension in place of R55 does not by itself move the DRG. What it changes is the clinical record and the Excludes1 compliance picture.

Where the workup establishes an arrhythmia, a conduction disorder or heart failure as the principal diagnosis, that condition drives the DRG in place of MS-DRG 312.

Medicare and commercial payers

There is no National Coverage Determination specific to syncope diagnosis coding.

R55 identifies an undetermined transient loss of consciousness. A device or an intervention whose coverage language requires a named cause will not be supported by R55 alone.

These coding and risk adjustment rules apply to Medicare Fee-for-Service and to Medicare Advantage plans using CMS-HCC v28 for payment year 2026.

WHERE SPECIFICITY IS LOST

R55 names no mechanism and no cause. There is no more specific code inside the family to step up to.

Reporting R55 after the workup has established a cause reports a symptom in place of the diagnosis. Section I.B.4 allows the symptom code only where a related definitive diagnosis has not been established.

Reporting R55 alongside a code in its Excludes1 note for the same condition is an Excludes1 violation. Orthostatic hypotension (I95.1) and carotid sinus syncope (G90.01) are the two that sit closest to the R55 fact pattern.

Reporting R55 for a fall loses the fall. The fall is recorded by an external cause code from W00–X58. The injury is coded from chapter 19.

Reporting R55 for a convulsion or for a cardiac arrest misstates the event. A convulsion without an established epilepsy diagnosis belongs in category R56. A pulseless event requiring resuscitation belongs in category I46.

Reporting R42 for a documented presyncope sets aside the Index instruction. The main term Syncope (near) (pre-) sends near syncope and presyncope to R55.

SEVERITY DESIGNATION (MS-DRG V44.0)

R55 carries no severity designation. It appears in neither Appendix G, the CC list, nor Appendix H, the MCC list, of the ICD-10 MS-DRG Definitions Manual Version 44.0. A case reaches the higher tier of its DRG pair on a designation carried by another diagnosis.

Documentation checklist to support R55

Chart elements that support code selection and reduce specificity-driven denials.

Provider documentation of a transient loss of consciousness with spontaneous recovery, or of a collapse, a blackout or a faint.

A record showing that no underlying cause has been established as the definitive diagnosis for this encounter, which is what supports a symptom code under Section I.B.4.

Absence of every condition named in the R55 Excludes1 note. Orthostatic hypotension, carotid sinus syncope, heat syncope, psychogenic syncope and the shock codes each replace R55 rather than accompany it.

Orthostatic vital signs and their result, where they were taken. A documented orthostatic drop moves the encounter to I95.1.

How the provider characterized any convulsive movement during the event. A seizure moves the encounter to category R56 or to category G40. Jerking during a faint is still syncope.

Whether a pulse was present and whether resuscitation was performed. A pulseless arrest is cardiac arrest in category I46, not syncope.

Whether the patient fell, with any resulting injury. The fall needs an external cause code from W00–X58. The injury needs a code from chapter 19.

The workup performed and its results, including ECG, telemetry, echocardiography and orthostatic testing, which is what shows the cause was sought and not found.

For outpatient encounters, documentation of the event as it occurred. A suspected arrhythmia or a rule out seizure is not coded in the outpatient setting.

FAQ

Is R55 billable without a decimal?

Yes. R55 is billable at three characters. It has no child codes. There is no R55.0 and no R55.9 to look for. Nothing is added after the three characters. R55 is complete as written. Readers arriving expecting a decimal will not find one.

Which syncope terms stay at R55?

Blackout, Fainting and Vasovagal attack are printed as inclusion terms at R55 in the FY2027 tabular. The Alphabetic Index sub-entries for vasovagal, vasodepressor, vasomotor, cardiac and heart syncope all resolve to R55. The Index main term is printed Syncope (near) (pre-) with code R55, which keeps presyncope and near syncope at R55 as well. Naming the reflex mechanism does not move the encounter. What moves it is a named cause. The R55 Excludes1 note lists the codes those causes carry.

Is syncope the same as a seizure or a cardiac arrest?

No. R55 covers a transient loss of consciousness with spontaneous recovery. A convulsion where no epilepsy diagnosis has been established is R56.9, unspecified convulsions. An established epilepsy diagnosis moves the encounter to category G40. A pulseless event requiring resuscitation is cardiac arrest in category I46. R55 carries no Excludes1 note for R56, for G40 or for I46. The separation rests on what the provider documents about the event, not on a tabular exclusion.

What must the record show to support R55?

The record must show a documented transient loss of consciousness, a collapse, a blackout or a faint. It must show that the cause was sought and not established for this encounter. It must not document, as the cause, a condition named in the R55 Excludes1 note, which includes orthostatic hypotension, carotid sinus syncope, heat syncope, psychogenic syncope, neurocirculatory asthenia, Stokes-Adams attack and the shock codes. Where orthostatic vital signs were taken, the record shows their result. Where the patient fell, it shows the fall and any injury.

Does R55 map to an HCC under CMS-HCC v28?

No. Published CMS-HCC v28 category code lists do not include R55. Syncope is a symptom and the model assigns it no weight. The condition that risk adjusts is the cause. Where a specified arrhythmia is documented, that arrhythmia maps to HCC 238, Specified Heart Arrhythmias. CC and MCC designation is a separate question from HCC mapping. R55 is on neither the MCC list nor the CC list for FY2027 (CMS Tables 6I and 6J).

How is R55 sequenced in the inpatient and outpatient settings?

Sequence R55 as the principal or first listed diagnosis where the syncope is the reason for the encounter and no cause has been established. Once the workup establishes a cause, that condition takes the principal diagnosis position. R55 is then not reported as an additional code where the syncope is integral to the established condition, under Section I.B.5 of the FY2027 Official Guidelines. In the outpatient setting, a suspected arrhythmia or a rule out seizure is not coded. The documented syncope is coded instead, under Section IV.H. On the inpatient side, a diagnosis documented as uncertain at discharge may be coded as though established under Section II.H, the guideline for uncertain diagnoses. That guideline can move an inpatient encounter off R55 where the discharge summary names a probable cause.

How does R55 work when the patient fell?

R55 records the cause of the fall. The fall itself is an external cause and takes a code from W00–X58, such as W19.XXXA for an unspecified fall at an initial encounter. External cause of morbidity codes are never recorded as a principal diagnosis under Section I.C.20.a.6 of the FY2027 Official Guidelines. Sequence the injury or the syncope first, then add the external cause code. Where the record documents repeated falls rather than a single event, R29.6 is available. Z91.81 records a history of falling.

What changed for R55 in FY2027?

R55 is unchanged in the FY2027 update, effective 1 October 2026. The FY2027 addenda add no child code beneath it and change no note at it. New FY2027 code I49.82, Ventricular bigeminy, carries a Use additional note that names syncope (R55) as an associated symptom.

Related codes

Codes in the same family as R55. Only codes with a published page render as links.

Sibling codes in the R55 family

R56.9: Unspecified convulsions.
R57.0: Cardiogenic shock.
R57.1: Hypovolemic shock.
R57.9: Shock, unspecified.
R53.1: Weakness.

Additional codes to consider

Codes outside the R55 family considered alongside R55.

Companion: code alongside when documented

W19.XXXA: Unspecified fall, initial encounter, where the syncope caused a fall and an injury from the fall is coded (Guideline I.C.20.a.1).
R29.6: Repeated falls, where the patient has recently fallen and the reason for the fall is being investigated (Guideline I.C.18.d).
Z91.81: History of falling, where the patient has fallen in the past and is at risk for future falls (Guideline I.C.18.d).
R05.4: Cough syncope, reported after R55 when the syncope occurs with cough. R05.4 carries a Code first note for syncope and collapse (R55). The Index sends Cough, syncope to R05.4.
Y92.-: Place of occurrence of the external cause, reported after the fall code (Guideline I.C.20.b).

Consider instead

I95.1: Orthostatic hypotension, named in the R55 Excludes1 note.
G90.01: Carotid sinus syncope, named in the R55 Excludes1 note.
G90.3: Multi-system degeneration of the autonomic nervous system, the code the Excludes1 note gives for neurogenic orthostatic hypotension.
T67.1XXA: Heat syncope, initial encounter, the code the Excludes1 note names as heat syncope.
F48.8: Other specified nonpsychotic mental disorders, the code the Excludes1 note gives for psychogenic syncope.
F45.8: Other somatoform disorders, the code the Excludes1 note gives for neurocirculatory asthenia.
I45.9: Conduction disorder, unspecified, the code the Excludes1 note gives for Stokes-Adams attack.
R57.0: Cardiogenic shock, named in the R55 Excludes1 note.
R57.9: Shock, unspecified, the code the Excludes1 note gives for shock NOS.
T81.10XA: Postprocedural shock unspecified, initial encounter, which carries Collapse NOS during or resulting from a procedure as an inclusion term.
R40.20: Unspecified coma, within the subcategory the Excludes1 note names for unconsciousness NOS.
R42: Dizziness and giddiness, where the record documents light-headedness or dizziness without a near faint.
R56.9: Unspecified convulsions, for a convulsion where no epilepsy diagnosis has been established.
I46.9: Cardiac arrest, cause unspecified, for a pulseless event requiring resuscitation.
I49.5: Sick sinus syndrome, where an arrhythmia is documented as the cause.
I48.91: Unspecified atrial fibrillation, where an arrhythmia is documented as the cause.
I44.2: Atrioventricular block, complete, where a conduction disorder is documented as the cause.
R00.1: Bradycardia, unspecified, which the Alphabetic Index gives for the sub-entry Syncope, bradycardia.
G97.1: Other reaction to spinal and lumbar puncture, which the Alphabetic Index gives for syncope due to spinal or lumbar puncture.
I20.89: Other forms of angina pectoris, which the Alphabetic Index gives for syncope anginosa.
G45.9: Transient cerebral ischemic attack, unspecified, where a TIA is established as the cause.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software