Bma Illustrated Medical Dictionary

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 DNAA section of DNA

from an organism that has been artific-

ially spliced into the DNA of another

organism. (See genetic engineering.)

reconstructive surgerySee arterial

reconstructive surgery; plastic surgery.

recovery position The position in

which to place an unconscious, breath-

ing casualty, while waiting for medical

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 bleedingThe passage of blood

from the rectumor anus. The blood may

be red, dark brown, or black. It may be

mixed with, or on the surface of, faecesor

passed separately, and there may be pain.

Haemorrhoidsare 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 polypscan also cause bleeding. Dis-

orders of the colon such as diverticular

diseasemay 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 arectal examination,

from proctoscopy, sigmoidoscopy, colon-

oscopy, or a double-contrast barium

X-ray examination.

rectal examinationExamination of the

anusand 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

tumoursof the rectum or prostate gland.

rectal prolapse

Protrusion outside

the anusof 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 faecesmay occur.

Treatment is with a fibre-rich diet.

Surgery may also be performed.

rectoceleBulging inwards and down-

wards of the back wall of the vagina as

the rectumpushes against weakened tis-

sues in the vaginal wall. A rectocele is

usually associated with a cystoceleor a

prolapsed uterus (see uterus, prolapse of).

There may be no symptoms, or the

rectocele may cause constipation. Pelvic

floor exercisesmay help. If not, an oper-

ation to tighten the tissues at the back

of the vagina may be recommended.

rectumA 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 examinationand proctoscopyor

by sigmoidoscopy.

RECOMBINANT DNA RECTUM

R

RECOVERY POSITION

Victim’s hand

supporting the head

Leg bent

Head tilted back to

keep airway open