skin. Hereditary coproporphyria also has
similar effects and may cause addi-
tional skin symptoms.
Protoporphyria usually causes skin
symptoms after exposure to sunlight, as
does porphyria cutanea tarda. In this
type, wounds are slow to heal, and
urine is sometimes pink or brown. Many
cases are precipitated by liver disease.
The rarest and most serious form, con-
genital erythropoietic porphyria, causes
red discoloration of urine and the teeth,
excessive hair growth, severe skin blis-
tering and ulceration, and haemolytic
anaemia. Death may occur in childhood.
Diagnosis is made from abnormal lev-
els of porphyrins in the urine and faeces.
Treatment is difficult. Avoiding sunlight
and/or precipitating drugs is the most
important measure. Acute intermittent
porphyria, variegate porphyria, and hered-
itary coproporphyria may be helped by
administration of glucoseor haematin.
Cases of porphyriacutanea tarda may be
helped byvenesection.
portal hypertensionIncreased blood
pressure in the portal vein, which car-
ries blood from the stomach, intestine,
and spleen to the liver. This causes
oesophageal varices, which may rupture
and cause internal bleeding, and ascites.
The most common cause of portal
hypertension is cirrhosis.
Diagnosis is usually made from the
symptoms and signs. Doppler ultrasound
scanningmay be used to assess the pres-
sure in the portal vein. Various treatments
may be used to stop bleeding or prevent
further bleeding. For example, ruptured
blood vessels may be treated by scle-
rotherapy, in which a chemical is injected
into the veins to block them. A shuntis
sometimes carried out to prevent fur-
ther bleeding. Ascites is controlled by
restriction of salt and with diuretic drugs.
port-wine stainA purple-red birth-
mark that is level with the skin’s surface.
It is a permanent type of haemangioma.
positron emission tomographySee
PET scanning.
possetingA term for the regurgitation
of small quantities of milk by infants
after they have been fed.
postcoital contraceptionSee contra-
ception, emergency.posteriorRelating to the back of the
body, or referring to the rear part.
postherpetic neuralgiaBurning pain
caused by nerve irritation that occurs at
the site of a previous attack of herpes
zoster(shingles). See neuralgia.
postmaturityA condition in which a
pregnancy persists for longer than 42
weeks; the average length of a normal
pregnancy is 40 weeks (see gestation).
Postmaturity may be associated with a
family tendency to prolonged pregnancy,
or it may be a sign that the baby is
unable to descend properly (see engage-
ment). The risk of fetal death increases
after 42 weeks because the placentabe-
comes less efficient. Postmature infants
tend to have dry skin and may be more
susceptible to infection.
postmortem examinationAn alterna-
tive term for an autopsy.
postmyocardial infarction syndrome
Another name for Dressler’s syndrome.
postnasal dripA watery or sticky dis-
charge from the back of the nose into
the nasopharynx. The fluid may cause a
cough, hoarseness, or the feeling of a
foreign body. The usual cause is rhinitis.
postnatal careCare of the mother after
childbirthuntil about 6 weeks later.
postnatal depressionDepression in a
woman after childbirth. The cause is
probably a combination of sudden hor-
monal changes and psychological and
environmental factors. The depression
ranges from an extremely common and
mild, shortlived episode (“baby blues”)
to a rare, severe depressive psychosis.
Most mothers first get the “blues” 4–5
days after childbirth and may feel mis-
erable, irritable, and tearful. The cause
is hormonal changes, perhaps coupled
with a sense of anticlimax or an over-
whelming sense of responsibility for the
baby. With reassurance and support, the
depression usually passes in 2–3 days. In
about 10–15 per cent of women, the
depression lasts for weeks and causes a
constant feeling of tiredness, difficulty
in sleeping, loss of appetite, and rest-
lessness. The condition usually clears
up of its own accord or is treated with
antidepressant drugs.
Depressive psychosis usually starts 2–3
weeks after childbirth, causing severePORTAL HYPERTENSION POSTNATAL DEPRESSIONP