RECOMBINANT DNA
RECTUM
is overridden by the “brown eye” gene,
and the child has brown eyes. The child
must inherit the recessive blue eye gene
from both parents in order to have blue
eyes. Many genetic disorders are deter-
mined by a recessive gene. Examples
include
cystic fibrosis
and
sickle cell
anaemia.
The child will only have the
disease if he or she inherits the gene
from both parents.
recombinant DNA A section of
DNA
from an organism that has been artific-
ially spliced into the DNA of another
organism. (See
genetic
engineering.)
reconstructive
surgery See
arterial
reconstructive surgery; plastic surgery.
recovery
position The position in
which to place an unconscious, breath-
ing casualty, while waiting for medical
RECOVERY POSITION
help. The body is placed on its side with
the upper leg bent at a right angle; the
lower leg is kept straight. The lower arm
is bent at a right angle; the upper is
bent with the palm of the hand placed
against the lower cheek to support the
head, which is tilted back to keep the
airway open. Casualties with suspected
spinal injuries should not be placed in
the recovery position.
rectal bleeding The passage of blood
from the
rectum
or
anus
. The blood may
be red, dark brown, or black. It may be
mixed with, or on the surface of,
faeces
or
passed separately, and there may be pain.
Haemorrhoids
are the most common
cause of rectal bleeding. Small amounts
of bright red blood appear on the surface
of faeces or on toilet paper.
Anal fissure
,
anal fistula
,
proctitis
, or
rectal prolapse
may also cause rectal bleeding.
Cancer of the colon (see
colon, cancer
of) or the rectum (see
rectum, cancer
of),
or
polyps
can also cause bleeding. Dis-
orders of the colon such as
diverticular
disease
may cause dark red faeces. Black
faeces (
melaena
) may be due to bleed-
ing high in the digestive tract. Bloody
diarrhoea may be due to
ulcerative coli-
tis, amoebiasis,
or
shigellosis.
Diagnosis
may be made from a
rectal examination,
from p
roctoscopy
,
sigmoidoscopy
,
colon-
oscopy
, or a double-contrast
barium
X-ray examination.
rectal examination Examination of the
anus
and
rectum
, performed as part of a
general
physical examination
, to assess
symptoms of pain or changes in bowel
habits, and to check for the presence of
tumours
of the rectum or
prostate gland.
rectal
prolapse
Protrusion outside
the
anus
of the lin-
ing of the
rectum,
usually brought on
by straining to defe-
cate. The condition
commonly
causes
discomfort,
mucus
discharge, and
rec-
tal bleeding.
Rectal prolapse is
usually temporary
in young children
but is often perma-
nent in elderly people. If the prolapse is
large, leakage of
faeces
may occur.
Treatment is with a fibre-rich diet.
Surgery may also be performed.
rectocele Bulging inwards and down-
wards of the back wall of the
vagina
as
the
rectum
pushes against weakened tis-
sues in the vaginal wall. A rectocele is
usually associated with a
cystocele
or a
prolapsed uterus (see
uterus, prolapse of
).
There may be no symptoms, or the
rectocele may cause
constipation. Pelvic
floor exercises
may help. If not, an oper-
ation to tighten the tissues at the back
of the vagina may be recommended.
rectum A short, muscular tube that
forms the lowest part of the large intes-
tine and connects it to the
anus
.
Rectal disorders are diagnosed by
rectal examination
and
proctoscopy
or
by
sigmoidoscopy
.
Head tilted back to
keep airway open
R
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