Bma Illustrated Medical Dictionary

of urticaria in which weals form after

the skin is stroked. Urticaria sometimes

occurs with angioedema.

The cause of urticaria is often un-

known. The most common known cause

is an allergic reaction (see allergy),

often to a particular food, food additive,

or drug. Urticaria may also be caused by

exposure to heat, cold, or sunlight. Less

commonly, it may be associated with

another disorder, such as vasculitis, sys-

temic lupus erythematosus, or cancer.

Itching can be relieved by applying

calamine lotion or by taking antihis-

tamine drugs. More severe cases may

require corticosteroid drugs. Identifying

and avoiding known trigger factors can

help prevent future reactions. A tend-

ency to urticaria often disappears in

time without treatment.

urticaria, neonatalA very common,

harmless skin condition, also known as

erythema neonatorum or toxic eryth-

ema, that affects newborn infants. A

blotchy rash, in which raised white or

yellow lumps are surrounded by ill-

defined red areas of inflammation,

forms, mainly affecting the face, chest,

arms, and thighs. The cause of neonatal

urticaria is unknown. The rash usually

clears up without treatment.

uterine muscle relaxantsDrugs that

are used to delay the premature del-

ivery of a fetus. Beta 2 -adrenoceptor

stimulants, such as salbutamol, relax

the muscle of the uterusand may post-

pone labour for days or weeks in at-risk

pregnancies of 24–33 weeks’ gestation.

Delay of premature labour for up to 48

hours allows time for corticosteroid

drugsto be given to the mother to help

the fetal lungs to mature.

uterovaginal prolapse See uterus,

prolapse of.

uterusThe hollow, muscular organ of

the female reproductive system in which

the fertilized ovum(egg) normally be-

comes embedded and in which the

embryoand fetusdevelop. The uterus

is commonly known as the womb. It is

situated in the pelvic cavity, behind the

bladderand in front of the intestines.

In a nonpregnant woman, the uterus

is 7.5–10 cm long and weighs 60–90 g.

The lower part opens into the vaginaat

the cervix; the upper part opens into the

fallopian tubes. The inside is lined with

endometrium. The uterus expands in size

during pregnancy to accommodate the

growing baby. At full-term, the powerful

uterine muscles expel the baby via the

birth canal (see childbirth). After the

menopause, the endometrium atrophies

(becomes thinner) and the uterine mus-

cle and connective tissue are reduced.

Conditions that affect the uterus include

congenitaldisorders, such as malform-

ation or absence of the uterus; tumours,

including polyps, fibroids, and cancer

of the endometrium (see uterus, cancer

of); infections, causing endometritis; and

hormonal disorders. (See also uterus,

prolapse of; uterus, retroverted.)

uterus, cancer ofA malignant growth

in the tissues of the uterus. Cancer of

the uterus mainly affects the cervix (see

cervix, cancer of) and endometrium. In

rare cases, the uterine muscle is affected

by a type of cancer called a leiomyosar-

coma. The term uterine cancer usually

refers to cancer of the endometrium.

Risk factors for endometrial cancer

include anything that may raise oestro-

gen levels in the body, such as obesity, a

history of failure to ovulate, or taking

oestrogen hormones long term if these

are not balanced with progestogen drugs.

It is also more common in women who

have had few or no children.

Before the menopause, the first symp-

tom of cancer of the uterus may be

menorrhagiaor bleeding between per-

iods or after sexual intercourse; after

URTICARIA, NEONATAL UTERUS, CANCER OF

U

UTERUS

Uterus

Vagina

Bladder

Cervix

Fallopian tube Ovary