Mendelson's syndrome is an acute pneumonia caused by regurgitation of stomach contents and aspiration of chemical material, usually gastric juices. The pneumonia develops rapidly, and within hours the patient may become tachypnoeic, hypoxic and febrile. There is minimal sputum. The condition often follows anaesthesia when the gag reflex is depressed, particularly during pregnancy.
A secondary bacterial infection may develop - indicated by sputum, persistent fever, leukocytosis, and sepsis.
The differential of this condition includes cardiac failure and amniotic fluid embolism.