R

rapid gastric emptying A disorder, also called
dumping syndrome, in which food moves from
the STOMACHinto the SMALL INTESTINEincompletely
digested, resulting in the small intestine attempt-
ing to digest solid food particles. Normally the
digestive content that reaches the small intestine
is fairly liquefied. The incomplete gastric digestion
causes various gastrointestinal symptoms and
leads to MALABSORPTION. Rapid gastric emptying
typically occurs in people who have had stomach
surgery, particularly BARIATRIC SURGERYfor weight
loss. Some research studies suggest that rapid gas-
tric emptying in people who have not had stom-
ach surgery may be an early sign of type 2
DIABETES. The diagnostic path may include gas-
troscopy and BARIUM SWALLOWto rule out other
conditions. Treatment integrates dietary changes
and medications to slow PERISTALSIS. Dietary
changes include eating six small, low-carbohy-
drate meals throughout the day and drinking liq-
uids between, rather than with, meals.
See also ENDOSCOPY.

rebound tenderness A clinical sign of PERITONITIS
(generalized INFLAMMATION and INFECTION of the
abdominal cavity). During abdominal palpation,
the doctor presses slowly and firmly on the
abdomen, then suddenly releases the pressure.
The person feels a stabbing PAINwith release when
the result is positive and notices no change when
the result is negative. Rebound tenderness has a
high level of accuracy for both positive and nega-
tive results. Rebound tenderness often appears as
referred pain in appendicitis. The pressure and
release action applied to the left side of the
abdomen results in the person feeling pain on the
right side of the abdomen, at the approximate
location of the appendix.

See also DIGITAL RECTAL EXAMINATION(DRE).

rectal fistula An abnormal opening in the wall

of the RECTUM, often connecting the rectum with

another structure such as the URETHRA (rec-

tourethral fistula), the VAGINA (rectovaginal fis-

tula), or the ANUS(anorectal fistula). Rectal fistulas

may be congenital or acquired. Congenital fistulas

often occur in combination with other congenital

anomalies, notably those affecting the HEARTsuch

as tetralogy of Fallot (a collective of malformations

in the structure of the heart). Acquired rectal fis-

tulas may be idiopathic (without detectable

cause), though are more likely to occur in people

who have inflammatory conditions that affect the

gastrointestinal tract such as INFLAMMATORY BOWEL

DISEASE(IBD). RADIATION THERAPYas treatment for

PROSTATE CANCER, CERVICAL CANCER, OVARIAN CANCER,

COLORECTAL CANCER, or other cancers in the

abdomen can weaken the rectal wall, allowing fis-

tulas to develop. As well, fistulas involving any

portion of the gastrointestinal tract are frequent

complications of HIV/AIDS.

Symptoms vary with the location of the fistula

though often include FECAL INCONTINENCEor inap-

propriate presence of stool in the other involved

structure. The diagnostic path may include DIGITAL

RECTAL EXAMINATION(DRE), BARIUM ENEMA, and sig-

moidoscopy (endoscopic examination of the lower

COLON). Treatment is surgery to repair the fistula,

which can sometimes be extensive when the fis-

tula is long or deep. Potential complications vary

according to the nature of the OPERATIONnecessary.

In many people the surgical repairs end the symp-

toms and the person returns to his or her usual

activities with no further problems. In some peo-

ple, complications such as fecal incontinence arise

or new fistulas occur.

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