empyema

DEFINITION of empyema

empyema is the accumulation of pus (purulent exudate) within a natural, pre-existing anatomical cavity, most classically the pleural space (empyema thoracis/pyothorax), but also used for the gallbladder, mastoid, paranasal sinuses, orbit, and subdural space. Unlike an abscess, which forms a new, walled-off cavity carved out of tissue, empyema fills a cavity that already exists anatomically. In the chest, it typically develops in three stages: an initial free-flowing exudative parapneumonic effusion, progressing to a fibrinopurulent stage with loculations, and finally an organizing stage where a thick fibrous peel encases the lung, restricting expansion. It is most commonly a complication of bacterial pneumonia (parapneumonic empyema), but can also follow thoracic surgery, trauma, or esophageal perforation. Clinically distinguished from simple parapneumonic effusion by pleural fluid analysis (low pH <7.2, low glucose, elevated LDH, positive Gram stain/culture, or frank pus on aspiration).

---

ETYMOLOGY of empyema

greek From Greek empyema (ἐμπύημα), from empyein (ἐμπύειν) “to suppurate, fester,” itself from en- (“in”) + pyon (πύον, “pus”). Literally “a festering within.” The root py-/pyo- (“pus”) is highly productive in medical terminology, appearing in pyothorax, pyuria, pyoderma, and pyogenic.

---

ALIASES / ALTERNATE TERMS

Term	Context
Pyothorax	Direct clinical synonym for pleural/thoracic empyema
Empyema thoracis	Formal term specifying the pleural cavity
Complicated parapneumonic effusion	Preceding/overlapping stage, not yet frank pus
Empyema of gallbladder	Suppurative acute cholecystitis variant
Subdural empyema	Intracranial, subdural space collection

---

RELATED TERMS

• abscess — a new, walled-off collection of pus within tissue; empyema occupies a pre-existing cavity instead.
• pleural effusion — any fluid (not necessarily infected) in the pleural space; empyema is the infected, purulent subtype.
• Parapneumonic effusion — the precursor stage of thoracic empyema, seen with adjacent pneumonia before frank pus develops.
• decortication — surgical stripping of the fibrous peel in organized/chronic empyema to allow lung re-expansion.
• pyogenic — adjective describing pus-producing organisms or processes.
• mastoiditis — mastoid empyema is coded as acute mastoiditis with subperiosteal abscess.
• cholecystitis — empyema of the gallbladder is classified as a form of acute cholecystitis.

---

CODING CORNER

ICD-10-CM Codes

Thoracic/Pleural Empyema (J86 — Pyothorax)

Code	Description
J86.9	Pyothorax without fistula (empyema NOS, thoracic empyema)
J86.0	Pyothorax with fistula (bronchopleural or cutaneous fistula present)

ENT — Mastoid Empyema (Acute Mastoiditis with Subperiosteal Abscess)

Code	Description
H70.111	Acute mastoiditis with subperiosteal abscess, right ear
H70.112	Acute mastoiditis with subperiosteal abscess, left ear
H70.113	Acute mastoiditis with subperiosteal abscess, bilateral
H70.119	Acute mastoiditis with subperiosteal abscess, unspecified ear

ENT — Sinus Empyema

Code	Description
J01.90	Acute sinusitis, unspecified (acute sinus empyema)
J32.9	Chronic sinusitis, unspecified (chronic sinus empyema)

Ophthalmology — Orbital Empyema (Orbital Abscess)

Code	Description
H05.011	Abscess of orbit, right eye
H05.012	Abscess of orbit, left eye
H05.013	Abscess of orbit, bilateral
H05.019	Abscess of orbit, unspecified eye

Gallbladder Empyema

Code	Description
K81.0	Acute cholecystitis (includes empyema of gallbladder)

Intracranial — Subdural Empyema

Code	Description
G06.2	Extradural and subdural abscess, unspecified (subdural empyema)

CPT Codes

Thoracic Drainage/Decortication

CPT Code	Description
32551	Tube thoracostomy, includes water seal, when performed; open
32554	Thoracentesis, needle or catheter, aspiration of the pleural space; without imaging guidance
32556	Pleural drainage, percutaneous, with insertion of indwelling catheter; without imaging guidance
32220	Decortication, pulmonary (separate procedure); total
32225	Decortication, pulmonary (separate procedure); partial

ENT — Mastoid/Sinus Drainage

CPT Code	Description
69501	Mastoidectomy; complete
69511	Mastoidectomy; radical
31267	Nasal/sinus endoscopy, surgical, with maxillary antrostomy; with removal of tissue from maxillary sinus
31255	Nasal/sinus endoscopy, surgical; with ethmoidectomy, total (anterior and posterior)

⚠️ Coding Note: For thoracic empyema, J86.0 vs J86.9 hinges on documented presence of a bronchopleural or cutaneous fistula — query if fistula status is ambiguous. When empyema complicates pneumonia, sequencing follows the circumstances of admission (empyema is usually principal if it is the reason for the encounter; otherwise the underlying pneumonia may sequence first per official guidelines). Watch for undercoding when documentation says only “complicated pleural effusion” without confirmed pus/positive culture — this may not meet criteria for J86.- and should be queried rather than defaulted. Procedure selection (simple thoracentesis vs. tube thoracostomy vs. decortication) should match the documented stage (free-flowing vs. loculated/fibrinopurulent vs. organized with peel), since decortication (32220/32225) requires evidence of a restrictive fibrous rind, not just drainage. For mastoid and orbital empyema, laterality is mandatory — never default to unspecified when the operative note states a side.

---

DERIVATIONS of empyema

TABLE definition AS Definition
FROM #medterm 
WHERE length(filter(roots, (word) => econtains([[empyema]].roots, word))) > 0 AND file.name != [[empyema]].file.name
SORT file.name ASC

---

Query functionality

TABLE definition AS Definition
FROM #medterm
WHERE file.name != this.file.name
AND any(contains(this.description, description))

Med terms dictionary Appendix A Prefixes Appendix B Combining Forms Appendix C Suffixes Appendix D Suffix forms