be present from birth or may be a result
of adhesions. It requires emergency
treatment, usually by surgery.
vomitingInvoluntary forcible expulsion
of stomach contents through the mouth.
Vomiting may be preceded by nausea,
pallor, sweating, excessive salivation,
and slowed heart-rate. It occurs when
the vomiting centre in the brainstemis
activated by signals from 1 of 3 places
in the body: the digestive tract; the bal-
ancing mechanism of the inner ear; or
the brain, either due to thoughts and
emotions or via the part of the brain
that responds to poisons in the body.
The vomiting centre sends messages to
both the diaphragm, which presses
down on the stomach, and the abdomi-
nal wall, which presses inwards, thereby
expelling the stomach contents upwards
through the oesophagus.
Vomiting may be due to overindulgence
in food or alcohol, is a common side
effect of many drugs, and may follow
general anaesthesia. Vomiting is also
common in gastrointestinal disorders
such as peptic ulcer, acute appendicitis,
gastroenteritis, and food poisoning. Less
commonly, it isdue to obstruction (see
pyloric stenosis; intussusception) or a tu-
mour of the digestive tract. It may also
be due to inflammation (see hepatitis;
pancreatitis; cholecystitis).
Other possible causes are pressure on
the skull (see encephalitis; hydrocepha-
lus; brain tumour; head injury; migraine),
conditions affecting the ear’s balancing
mechanism (see Ménière’s disease; laby-
rinthitis; motion sickness), and hormonal
disorders (see Addison’s disease).
Vomiting may be a symptom of keto-
acidosis in poorly controlled diabetes
mellitus. It may also be a symptom of an
emotional problem or be part of the
disorders anorexia nervosaor bulimia.
Persistent vomiting requires medical
investigation. Treatment depends on the
cause. Antiemeticsmay be given. (See also
vomiting blood; vomiting in pregnancy.)
vomiting bloodA symptom of bleed-
ing from within the digestive tract.
Vomiting blood may be caused by a
tear in the lower oesophagus (see Mal-
lory–Weiss syndrome), bleeding from
oesophageal varices, erosive gastritis,
peptic ulcer, or, rarely, stomach cancer.
Blood can also be vomited if it is swal-
lowed during a nosebleed. Vomited
blood may be dark red, brown, black, or
may resemble coffee grounds. Vomiting
of blood is often accompanied by the
passing of black, tarry faeces.
The cause of vomiting blood is investi-
gated by endoscopyof the oesophagus
and stomach, or by barium X-ray exami-
nations. If blood loss is severe, blood
transfusion, and possibly surgery to
stop the bleeding, may be required.
vomiting in pregnancyNausea and
vomiting in early pregnancyare com-
mon and are most likely to be caused
by changes in the hormone levels. Vom-
iting occurs most frequently in the
morning, but it may occur at any time. It
is sometimes precipitated by stress,
travelling, or food.
In rare cases, the vomiting becomes
severe and prolonged. This can cause
dehydration, nutritional deficiency, altera-
tions in blood acidity, and weight loss.
Immediate hospital admission is then
required to replace lost fluids and
chemicals by intravenous infusion, to
rule out any serious underlying disor-
der, and to control the vomiting.
von Recklinghausen’s diseaseAn-
othername for neurofibromatosis.
von Willebrand’s diseaseAn inheri-
ted lifelong bleeding disordersimilar to
haemophilia. People with the condition
have a reduced concentration in their
blood of a substance called von Wille-
brand factor, which helps plateletsin
the blood to plug injured blood vessel
walls and forms part of factor VIII(a
substance vital to blood coagulation).
Symptoms of deficiency of this factor
include excessive bleeding from the
gums and from cuts and nosebleeds.
Women may have heavy menstrual bleed-
ing. In severe cases, bleeding into joints
and muscles may occur.
The disease is diagnosed by blood-
clotting testsand measurement of blood
levels of von Willebrand factor. Bleeding
episodes can be prevented or controlled
by desmopressin (a substance resem-
bling ADH). Factor VIII or concentrated
von Willebrand factor may also be used
to treat bleeding.VOMITING VON WILLEBRAND’S DISEASE
V