Vomiting

Definition:

Vomiting is the forceful ejection of gastric contents through the mouth. There are three phases:

Nausea – A feeling of wanting to vomit often associated with autonomic effects (including hypersalivation, pallor and sweating)

Retching – A strong involuntary effort to vomit

Vomiting – The expulsion of gastric contents through the mouth

Control of vomiting:

The vomiting centres are located in the lateral reticular formation of the medulla and are stimulated by the chemoreceptor trigger zones (CTZs) in the floor of the fourth ventricle, and also by afferents from the gut.

The zones are directly stimulated by:

Drugs

Motion

Metabolic causes

Aetiology:

There are many causes of vomiting (see below) but nausea and vomiting without pain are frequently non-GI in origin.

Large volumes of vomit suggest intestinal obstruction

Faeculent vomit suggests low intestinal obstruction from a gastrocolic fistula

Projectile vomiting is associated with pyloric stenosis

Chronic nausea and vomiting with no other abdominal symptoms usually have psychological causes.

Early morning vomiting is seen in:

Pregnancy

Alcohol dependence

Some metabolic disturbances (e.g. uraemia)

Causes of vomiting:

Any GI disease

Acute infections:

Influenza

Pertussis

CNS disease:

Raised ICP

Meningitis

Vestibular disturbances

Migraine

Metabolic causes:

Uraemia

Diabetes (ketoacidosis or gastroparesis)

Hypercalcaemia

Vomiting

Drugs (many!):

Digitalis toxicity

Opiates

Cytotoxics

Reflex:

Severe pain

Infarction

Psychogenesis

Pregnancy

Alcohol excess