2026 ICD-10-CM Diagnosis Code T78.3XXSAngioneurotic edema, sequela
T78.3XXS is a billable ICD-10-CM diagnosis code for angioneurotic edema, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T78.3XXS is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- ACE inhibitor-aggravated angioedema
- Acquired angioedema due to C1 inhibitor autoantibody
- Acquired angioedema due to lymphoproliferative disorder
- Acquired angioedema type I
- Acquired angioedema type II
- Acquired C1 esterase inhibitor deficiency
- Allergic angioedema
- Allergic angioedema due to bite and/or sting
- Allergic angioedema due to ingested food
- Allergic urticaria and/or angioedema
- Allergic urticaria caused by ingested food
- Angioedema
- Angioedema and/or urticaria
- Angioedema caused by angiotensin-converting-enzyme inhibitor
- Angioedema due to disorder of kinin metabolism
- Angioedema of eyelid
- Angioedema of lip
- Angioedema of tongue
- Aspirin-induced angioedema-urticaria
- Autoimmune angioedema
- Autoimmune urticaria and/or angioedema
- Azo-dye-induced angioedema-urticaria
- Chemical-aggravated angioedema-urticaria
- Cholinergic angioedema
- Cutis laxa following urticaria-angioedema
- Cutis laxa, acquired type
- Disorder of eosinophil
- Drug-aggravated angioedema-urticaria
- Drug-induced angioedema-urticaria
- Edema of intestinal tract
- Edema of oral soft tissues
- Edema of the tongue
- Episodic angioedema with eosinophilia
- Episodic eosinophilia
- Food-induced angioedema-urticaria
- Giant urticaria
- Hevea brasiliensis latex protein-induced angioedema-urticaria
- Idiopathic angioedema
- Idiopathic urticaria and/or angioedema
- Intestinal angioedema caused by angiotensin-converting enzyme inhibitor
- NSAID-induced angioedema-urticaria
- Penicillin-induced angioedema-urticaria
- Physical angioedema
- Respiratory angioedema
- Sodium benzoate-induced angioedema-urticaria
- Urticaria caused by food additive
- Urticaria caused by salicylate
- Urticaria medicamentosa
- Venom-induced angioedema-urticaria
- Vibratory angioedema
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Adverse effects, not elsewhere classified (T78). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Angioedema
swelling involving the deep dermis, subcutaneous, or submucosal tissues, representing localized edema. angioedema often occurs in the face, lips, tongue, and larynx.Angioedemas, Hereditary
inherited disorders that are characterized by subcutaneous and submucosal edema in the upper respiratory tract and gastrointestinal tract.Hereditary Angioedema Type III
a form of hereditary angioedema that occurs in women and is precipitated or worsened by high estrogen levels. it is associated with mutations in the gene for factor xii that result in its increased activity.Hereditary Angioedema Types I and II
forms of hereditary angioedema that occur due to mutations in the gene for complement c1 inhibitor protein. type i hereditary angioedema is associated with reduced serum levels of complement c1 inhibitor protein. type ii hereditary angioedema is associated with the production of a non-functional complement c1 inhibitor protein.Angioedema
rapid swelling of the deep layers of the skin due to transient vascular leakage of serous fluid.Hereditary Angioedema
autosomal dominant inherited disorder characterized by abnormalities of c1 inhibitor. patients present with swelling of the skin, subcutaneous tissues, and mucosa sites.Hereditary Angioedema Types I and II
autosomal dominant inherited disorders characterized by abnormalities of c1 inhibitor. patients present with swelling of the skin, subcutaneous tissues, and mucosa sites. in type i hereditary angioedema, the plasma levels of c1 inhibitor are decreased. in type ii hereditary angioedema, the c1 inhibitor is dysfunctional and its plasma levels may be normal or elevated.SERPING1 wt Allele|Angioedema, Hereditary Gene|C1IN|C1INH|C1NH|HAE1|HAE2|Serine (or Cysteine) Proteinase Inhibitor, Clade G (C1 Inhibitor), Member 1, (Angioedema, Hereditary) Gene|Serine/Cysteine Proteinase Inhibitor Clade G Member 1 Gene|Serpin Family G Member 1 wt Allele|Serpin Peptidase Inhibitor, Clade G (C1 Inhibitor), Member 1 Gene|Serpin Peptidase Inhibitor, Clade G, Member 1 Gene
human serping1 wild-type allele is located in the vicinity of 11q12.1 and is approximately 22 kb in length. this allele, which encodes plasma protease c1 inhibitor protein, plays a role in serine proteinase inhibition. mutation of the gene is associated with hereditary angioedema types 1 and 2 and partial deficiency of complement component 4.
Patient EducationClinical
Allergy
An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are:
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Convert T78.3XXS to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T78.3XXSOverview
Is T78.3XXS (Angioneurotic edema) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report angioneurotic edema, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T78.3XXS mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the angioneurotic edema itself has resolved, not the original event.
What MS-DRG does T78.3XXS group to?
When angioneurotic edema, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T78.3XXS exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for angioneurotic edema, sequela on inpatient claims.
What is the ICD-9 equivalent of T78.3XXS?
Under the General Equivalence Mappings, angioneurotic edema, sequela converts to ICD-9-CM 909.9 (late eff exter cause NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
