refluxAn 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 regurgitationof acid
fluid from the stomach (see acid reflux).
refractionThe bending of light rays as
they pass from one substance to anoth-
er. It is the mechanism by which images
are focused on the retinain the eye.
regressionA term used in psychoana-
lytic theoryto describe the process of
returning to a childhood level of behavi-
our, such as thumb-sucking.
regurgitationA backflow of fluid. In
medicine, the term is used to describe
the return of swallowed food or drink
from the stomach into the oesophagus
and mouth. The term is also used to
describe the backflow of blood through
a heart valvethat does not close fully
because of a disorder such as mitral
incompetence. (See also reflux.)
rehabilitationTreatment aimed at enab-
ling a person to live an independent life
following injury, illness, alcohol depen-
dence, or drug dependence. Treatment
may include physiotherapy, occupational
therapy, and psychotherapy.
In a rehabilitation centre, a person’s
disabilityor 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 ther-
apy.
rehydration therapyThe treatment of
dehydrationby administering fluids and
salts by mouth (oral rehydration) or by
intravenous infusion. The amount of fluid
necessary depends on age, weight, and
the degree of dehydration. Mild dehy-
dration can usually be treatedwith 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 intra-
venous infusionof salineand/or glucose
solution may be given in hospital.
reimplantation, dentalReplacement of
a toothin its socket after an accident sothat 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
splinting, dental) while it heals. Healing
may take several weeks.
Reiter’s syndromeA condition in which
there is a combination of urethritis, re-
active arthritis, and conjunctivitis. There
may also be uveitis. Reiter’s syndrome is
more common in men.
The syndrome is caused by an immune
responseand usually develops only in
people with a genetic predisposition.
Most patients have the HLA-B27 tissue
type (see histocompatability antigens).
The syndrome’s development is induced
by infection: usually nongonococcal ure-
thritis, but sometimes bacillary dysentery.
Reiter’s syndrome usually starts with a
urethral discharge, which is followed by
conjunctivitis and then arthritis. The
arthritis usually affects 1 or 2 joints
(usually the knee and/or ankle) and is
often associated with feverand malaise.
Attacks can last for several months.
Tendons, ligaments, and tissue in the
soles of the feet may also become in-
flamed. Skin rashes are common.
Diagnosis is made from the symptoms.
Analgesic drugsand nonsteroidal anti-
inflammatory drugs relieve symptoms
but may have to be taken for a long peri-
od.Relapsesoccur in about 1 in 3 cases.
rejectionAn immune responseaimed at
destroying organisms or substances that
the body’s immune systemrecognizes as
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 tissue-typing). Immuno-
suppressant drugs, corticosteroid drugs,
and ciclosporinare given to organ trans-
plant recipients to suppress rejection.
(See also grafting; transplant surgery.)
relapseThe recurrence of a disease
after an apparent recovery, or the return
of symptoms after a remission.
relapsing feverAn illness caused by
infection with spirochaetes. Relapsing
fever is transmitted to humans by ticks
or liceand is characterized by high fever.
It does not occur in the UK.REFLUX RELAPSING FEVERR