Pancreas
A gland that makes enzymes for digestion and the hormone insulin.

Pancreatitis
Irritation of the pancreas that can make it stop working. Most often caused by gallstones or alcohol abuse.

Papillary Stenosis
A condition in which the openings of the bile ducts and pancreatic ducts narrow.

Parenteral Nutrition
A way to provide a liquid food mixture through a special tube in the chest. Also called hyperalimentation or total parenteral nutrition.

Parietal Cells
Cells in the stomach wall that make hydrochloric acid.

Pediatric Gastroenterologist
A doctor who treats children with digestive diseases.

Pepsin
An enzyme made in the stomach that breaks down proteins.

Peptic Ulcer
An ulcer in the wall of the stomach or duodenum resulting from the digestive action of the gastric juice on the mucous membrane when the latter is rendered susceptible to its action (as by psychosomatic or local factors)

Peptic
Related to the stomach and the duodenum, where pepsin is present.

Peptic Ulcer
A sore in the lining of the esophagus, stomach, or duodenum. Usually caused by the bacterium Helicobacter pylori. An ulcer in the stomach is a gastric ulcer; an ulcer in the duodenum is a duodenal ulcer.

Percutaneous
Passing through the skin.

Percutaneous Transhepatic Cholangiography
X-rays of the gallbladder and bile ducts. A dye is injected through the abdomen to make the organs show up on the x-ray.

Perforated Ulcer
An ulcer that breaks through the wall of the stomach or the duodenum. Causes stomach contents to leak into the abdominal cavity.

Perforation
(PUR-fuh-RAY-shun)
A hole in the wall of an organ.

Perianal
The area around the anus.

Perineal
Related to the perineum.

Perineum
The area between the anus and the sex organs.

Peristalsis
A wavelike movement of muscles in the GI tract. Peristalsis moves food and liquid through the GI tract.

Peritoneum
The lining of the abdominal cavity.

Peritonitis
Infection of the peritoneum.

Pernicious Anemia
Anemia caused by a lack of vitamin B12. The body needs B12 to make red blood cells.

Peutz-Jeghers Syndrome
An inherited condition. Many polyps grow in the intestine. There is little risk of cancer.

Pharynx
The space behind the mouth. Serves as a passage for food from the mouth to the esophagus and for air from the nose and mouth to the larynx.

Polyp
Tissue bulging from the surface of an organ. Although these growths are not normal, they often are not cause for concern. However, people who have polyps in the colon may have an increased risk of colorectal cancer.

Polyposis
The presence of many polyps.

Porphyria
A group of rare, inherited blood disorders. When a person has porphyria, cells fail to change chemicals (porphyrins) to the substance (heme) that gives blood its color. Porphyrins then build up in the body. They show up in large amounts in stool and urine, causing the urine to be colored reddish-purple.

Portal Hypertension
High blood pressure in the portal vein. This vein carries blood into the liver. Portal hypertension is caused by a blood clot. This is a common complication of cirrhosis.

Portal Vein
The large vein that carries blood from the intestines and spleen to the liver.

Portosystemic Shunt
An operation to create an opening between the portal vein and other veins around the liver.

Postcholecystectomy Syndrome
A condition that occurs after gallbladder removal. The muscle between the gallbladder and the small intestine does not work properly, causing pain, nausea, and indigestion. Also called biliary dyskinesia.

Postgastrectomy Syndrome
A condition that occurs after an operation to remove the stomach (gastrectomy). See also Dumping Syndrome.

Postvagotomy Stasis
Delayed stomach emptying. Occurs after surgery on the vagus nerve.

Pouch
A special bag worn over a stoma to collect stool. Also called an ostomy appliance.

Primary Biliary Cirrhosis
A chronic liver disease. Slowly destroys the bile ducts in the liver. This prevents release of bile. Long-term irritation of the liver may cause scarring and cirrhosis in later stages of the disease.

Primary Sclerosing Cholangitis
Irritation, scarring, and narrowing of the bile ducts inside and outside the liver. Bile builds up in the liver and may damage its cells. Many people with this condition also have ulcerative colitis.

Proctalgia Fugax
Intense pain in the rectum that occasionally happens at night. Caused by muscle spasms around the anus.

Proctectomy
An operation to remove the rectum.

Proctitis
Irritation of the rectum.

Proctocolectomy
An operation to remove the colon and rectum. Also called coloproctectomy.

Proctocolitis
Irritation of the colon and rectum.

Proctologist
A doctor who specializes in disorders of the anus and rectum.

Proctoscope
A short, rigid metal tube used to look into the rectum and anus.

Proctoscopy
Looking into the rectum and anus with a proctoscope.

Proctosigmoiditis
Irritation of the rectum and the sigmoid colon.

Proctosigmoidoscopy
An endoscopic examination of the rectum and sigmoid colon. See also Endoscopy.

Prokinetic Drugs
Medicines that cause muscles in the GI tract to move food. An example is cisapride (SIS-uh-pryd) (Propulsid).

Prolapse
A condition that occurs when a body part slips from its normal position.

Protein
One of the three main classes of food. Protein is found in meat, eggs, and beans. The stomach and small intestine break down proteins into amino acids. The blood absorbs amino acids and uses them to build and mend cells. See also Amino Acids.

Proton Pump Inhibitors
Medicines that stop the stomach's acid pump. Examples are omeprazole (oh-MEH-prah-zol) (Prilosec) and lansoprazole
Prune Belly Syndrome
A condition of newborn babies. The baby has no abdominal muscles, so the stomach looks like a shriveled prune. Also called Eagle-Barrett syndrome.

Pruritus Ani
Itching around the anus.

Pseudomembranous Colitis
(SOO-doh-MEM-bray-nus koh-LY-tis)
Severe irritation of the colon. Caused by Clostridium difficile bacteria. Occurs after taking oral antibiotics, which kill bacteria that normally live in the colon.

Pyloric Sphincter
(py-LOR-ik SFEENK-tur)
The muscle between the stomach and the small intestine.

Pyloric Stenosis
(py-LOR-ik stuh-NOH-sis)
A narrowing of the opening between the stomach and the small intestine.

Pyloroplasty
(py-LOR-oh-plah-stee)
An operation to widen the opening between the stomach and the small intestine. This allows stomach contents to pass more freely from the stomach.

Pylorus
(py-LOR-us)
The opening from the stomach into the top of the small intestine (duodenum).