reflux An abnormal backflow of fluid in
a body passage due to failure of the
passage's exit to close fully. A common
type of reflux is
fluid from the stomach (see
refraction The bending of light rays as
they pass from one substance to anoth-
er. It is the mechanism by which images
are focused on the
in the eye.
regression A term used in
to describe the process of
returning to a childhood level of behavi-
our, such as thumb-sucking.
regurgitation A backflow of fluid. In
medicine, the term is used to describe
the return of swallowed food or drink
from the stomach into the
and mouth. The term is also used to
describe the backflow of blood through
that does not close fully
because of a disorder such as
rehabilitation Treatment aimed at enab-
ling a person to live an independent life
following injury, illness,
In a rehabilitation centre, a person's
or dependence is assessed
and a treatment programme is devel-
oped. Industrial rehabilitation centres
provide job retraining for those who
cannot return to their previous employ-
ment. Drug and alcohol rehabilitation
centres help people through withdrawal
and provide psychological support.
rehydration, oral See
rehydration therapy The treatment of
by administering fluids and
salts by mouth (oral rehydration) or by
. The amount of fluid
necessary depends on age, weight, and
the degree of dehydration. Mild dehy-
dration can usually be treated with oral
solutions, which are available as effer-
vescent tablet or powder to be made up
at home. In severe dehydration, or if the
patient cannot take fluids by mouth
because of nausea or vomiting, an
solution may be given in hospital.
reimplantation, dental Replacement of
in its socket after an accident so
that it can become reattached to sup-
porting tissues. The front teeth are most
commonly involved. The tooth needs to
be reimplanted soon after the accident
and is maintained with a splint (see
) while it heals. Healing
may take several weeks.
Reiter's syndrome A condition in which
there is a combination of
may also be
Reiter's syndrome is
more common in men.
The syndrome is caused by an
and usually develops only in
people with a genetic predisposition.
Most patients have the HLA-B27 tissue
The syndrome's development is induced
by infection: usually
, but sometimes bacillary
Reiter's syndrome usually starts with a
urethral discharge, which is followed by
conjunctivitis and then arthritis. The
arthritis usually affects
(usually the knee and/or ankle) and is
often associated with
Attacks can last for several months.
, and tissue in the
soles of the feet may also become in-
flamed. Skin rashes are common.
Diagnosis is made from the symptoms.
but may have to be taken for a long peri-
occur in about 1 in 3 cases.
destroying organisms or substances that
foreign. Rejection commonly refers to
the nonacceptance of tissue grafts or
organ transplants. To avoid rejection,
donor tissues are closely matched to
the recipient (see
are given to organ trans-
plant recipients to suppress rejection.
grafting; transplant surgery.)
relapse The recurrence of a disease
after an apparent recovery, or the return
of symptoms after a
relapsing fever An illness caused by
fever is transmitted to humans by
and is characterized by high fever.
It does not occur in the UK.