Radiation Colitis
(ray-dee-AY-shun koh-LY-tis)
Damage to the colon from radiation therapy.

Radiation Enteritis
(ray-dee-AY-shun en-tuh-RY-tis)
Damage to the small intestine from radiation therapy.

Radionuclide Scans
(RAY-dee-oh-NOO-clyd skanz)
Tests to find GI bleeding. Radioactive material is injected to highlight organs on a special camera. Also called scintigraphy (sihn-TIHG-ruh-fee).

Rapid Gastric Emptying
(RAH-pid GAH-strik EM-tee-ying)
See Dumping Syndrome.

Rectal Manometry
(REK-tul muh-NAW-muh-tree)
A test that uses a thin tube and balloon to measure pressure and movements of the rectal and anal sphincter muscles. Usually used to diagnose chronic constipation and fecal incontinence.

Rectal Prolapse
A condition in which the rectum slips so that it protrudes from the anus.

Rectum
The lower end of the large intestine, leading to the anus.

Reflux
A condition that occurs when gastric juices or small amounts of food from the stomach flow back into the esophagus and mouth. Also called regurgitation.

Reflux Esophagitis
Irritation of the esophagus because stomach contents flow back into the esophagus.

Regional Enteritis
See Crohn's Disease.

Regurgitation
See Reflux.

Retching
Dry vomiting.

Rotavirus
The most common cause of infectious diarrhea in the United States, especially in children under age 2.

Rupture
A break or tear in any organ or soft tissue.