Класифікація синовіальних випотів

Examination

Normal

Hemorrhagic

Infectious

Inflammatory

Noninflammatory

Gross examination

Appearance

Clear

Bloody

Turbid or purulent

Yellow, cloudy

Straw-colored, clear

Routine laboratory examination

Culture

Negative

Negative

Often positive

Negative

Negative

Polymorphonuclear leukocyte %*

< 25

Usually >85

> 50

< 25

White blood cell count*

<200/mcL

Affected by amount of blood

5,000–>100,000/mcL

1,000–50,000/mcL

200–1000/mcL

* White blood cell (WBC) count and polymorphonuclear leukocyte % in infectious arthritis are lower if the organism is less virulent (eg, in gonococcal, Lyme, tuberculous, or fungal arthritis) or partially treated. Some effusions in systemic lupus erythematosus and other systemic rheumatic diseases are only equivocally inflammatory, with a WBC count of 500–2000/mcL. Noninfectious effusions rarely have up to 100,000 WBC/mcL.