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Chapter 12
Gastroenterology
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
What is Gastroenterology?
• Gastroenterology
– Study of digestive system
• Gastroenterologist
– Cares for patients with digestive problems
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•
Gastrointestinal System Overview
– Also called the alimentary tract
– Functions:
• Digestion
• Absorption
• Excretion
– Components: mouth, throat, esophagus, stomach,
small intestine, largest intestine, rectum, and anus
– Accessory organs: pancreas, liver, and gallbladder.
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• Mouth (oral cavity) and throat
– Mouth contains hard palate, soft palate,
tongue, and uvula
– Throat (oropharynx) includes soft palate,
tonsils, posterior part of tongue and posterior
wall of throat
– Chewing breaks down food
– Food passes into throat
• Esophagus
– Connects the throat with the stomach
– Forces food down by muscle contractions
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• Stomach
– Receives food from esophagus
– Stores food and breaks it down
– Components:
• Cardia: top portion
• Fundus: left and above the cardia
• Body: large central part
• Antrum: lower portion
• Pylorus: between the stomach and small intestine
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• Small Intestine: “small bowel”
– Connects stomach to the large intestine
– Where actual digestion of food takes place
– Components:
• Duodenum: top portion
• Jejunum: middle portion
• Ileum: bottom portion
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• Large Intestine: “colon”
– Moves waste (stool) to be excreted by the body
(obstipation means the inability of the colon to pass
stool)
– Components:
• Cecum – absorbs remaining fluid after digestion
• Vermiform appendix
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• Colon
– Ascending colon: right-sided portion
– Transverse colon: top portion
– Descending colon: left-sided portion
– Sigmoid colon: bottom portion
– Rectum: chamber at the end of the colon until
defecation (release of stool) occurs
– Anus: opening at the end
– Anal sphincter: keeps anus closed until defecation
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Accessory Organs
• Accessory organs are not part of the digestive
tract but play a vital role in digestive activities
• Salivary Glands
– Three pairs:
• Parotid (side of the face and in front of and
below the external ear)
• Submandibular (beneath the mandible, or
lower jaw)
• Sublingual (under the tongue)
• Glands secrete saliva into the mouth to aid in chewing
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• Liver
– Largest organ in the body
– The falciform ligament divides the liver into right
and left lobes
– Cleanses blood and removes toxic substances that
may be ingested
– Plays key role in metabolism of sugars, fats, and
proteins
– Produces bile, a substance that assists in the
digestion and absorption of fats
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• Gallbladder and Biliary Tract
– Gallbladder is attached to the lower surface of the
liver which receives bile from the liver through
ducts to release it into the small intestine
– Biliary tract: A series of ducts name according to
the structures to which they are connected
• Hepatic ducts (right and left): Begin in the liver
• Cystic duct: Begins at gallbladder
• Pancreatic duct: Joins the pancreas
• Common bile duct: Convergence of right and
left hepatic ducts
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• Pancreas
– A large glandular structure that lies in front of the
upper spine and behind the stomach
– Releases digestive enzymes through biliary ducts into
the duodenum to aid in digestion
– Also part of the endocrine system, producing
hormones and chemicals to help regulate blood sugar
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The Digestive Process
• Process involves:
– Breaking down food
– Moving food through digestive tract
– Absorbing nutrients by the body
– Creating waste to be eliminated
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Process:
– Food is broken down in the mouth by chewing
– Food enters esophagus and is forced down to the
stomach by peristalsis (wave-like movements of
muscle)
– The stomach:
• Stores the swallowed food
• Mixes the food with digestive juices to create
chyme (mushy liquid)
• Empties chyme into small intestine
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– Small intestine receives chyme
– Enzymes break down fats, proteins, and sugars
– Bile breaks down fats
– Liquid is absorbed through cell walls to nourish the body
– Waste is passed to large intestine
– Colon absorbs liquid and passes solid waste through
– Stool reaches the rectum, where it is stored until
defecation occurs.
– Rectum contracts, expelling stool through anus.
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Common GI Diseases and Treatments
• Peptic Disorders: damage to the GI lining from stomach
acids or bacteria
– Gastritis: inflammation of stomach lining
• Causes: Certain foods, medications, Helicobacter pylori
(or H. pylori) bacteria
– Gastroesophageal reflux disease (GERD)
• Stomach acids flow back into esophagus
• Results: Inflammation, pain, stricture, globus sensation
• Barrett esophagus: actual change in the normal cell
makeup (called metaplasia) to abnormal cells in the
esophagus, increasing risk of cancer
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• Peptic Ulcer Disease (PUD): ulcers in stomach
(gastric ulcer), or duodenum (duodenal ulcer).
– Ulcers cause:
• Vomiting of blood (hematemesis)
• Black, tarry stools (melena)
• Tip: Stools are described as “melanotic,” NOT
“melenic”, a common dictation error
• Inflammation and infection of abdominal wall
(peritonitis)
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• Treatments for peptic ulcer disease:
• Medications:
• Antacids: Used to neutralize acid
• Histamine (H2) blockers: Reduce the secretion of
acid in the stomach
• Proton pump inhibitors (PPIs): Reduce acid
production and promote healing of ulcers faster than
H2 blockers alone
• Surgical procedures:
• Nissen fundoplication: Surgeons reconstruct the area
of the lower esophageal sphincter connecting the
esophagus and fundus of the stomach
• Term derives from fundo- (fundus) and –plication
(wrapping)
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• Vagotomy: Surgical cutting of the vagus nerve to reduce
acid secretions in the stomach
• Antrectomy: The surgical removal of the lower part of
the stomach, the area which produces a hormone that
stimulates the secretion of gastric juices
• Billroth Procedures
– Billroth I (gastroduodenostomy): Antrectomy as
above and surgically attaching remaining portion of
stomach to the duodenum
– Billroth II (gastrojejunostomy): Similar procedure
except remaining portion of stomach is attached to
the jejunum
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• Gallbladder Disease
– Gallstones: rock-like material in the gallbladder
• Cholelithiasis: gallstones in the gallbladder
• Choledocholithiasis: gallstones in the common
bile duct
– Treatment: Cholecystectomy
• Open: uses a large incision in the abdomen
• Laparoscopic: tiny incisions, faster recovery time
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• Pancreatic Disorders
– Pancreatitis: Inflammation and damage to the
pancreas by digestive juices
• Acute pancreatitis: Occurs suddenly
• Chronic pancreatitis: Slow, ongoing inflammation
causing scarring and pain
– Pancreatic cancer: Cancerous cells grow in the
pancreas, seldom detected in early stages
• Whipple procedure (also called
pancreaticoduodenectomy): Removes tumors from
the head of the pancreas, as well as duodenum
and other nearby tissues
• Cancer-killing drugs: 5-FU, Gemzar, Tarceva
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• Hepatitis: An inflammation of the cells of the liver,
causing injury or destruction
– Causes: Bacteria, drugs, tons, excess alcohol, or can
be caused by an autoimmune disorder
– Acute hepatitis: Sudden onset with limited course
– Chronic hepatitis: Slowly progressive and persistent
• Alcoholic hepatitis: Inflammation of the liver caused by
alcohol
• Nonalcoholic steatohepatitis (NASH), also called “fatty
liver disease”: Similar to alcoholic hepatitis but causes
injury related to fat (caused by obesity, diabetes)
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• Viral hepatitis: When any one of several hepatitis
viruses infect the liver and begin replicating. The most
serious form, delineated by types A through E:
– Hepatitis A (HAV) also called “infectious hepatitis” – most
common, spread by fecal-oral contamination, unwashed
hands
– Hepatitis B (HBV), spread by blood and other body fluids
– Hepatitis C (HCV), spread by blood and blood products.
Slowly progressive and mutates easily into new variations
• Genetic variants are called genotypes (6) with
subtypes which are dictated as arabic numbers 1
through 6 with subtypes classified alphabetically, for
example: HCV, genotype 1a.
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– Diagnosed by blood tests:
• Levels of liver enzymes
• Antigen tests: presence of virus in the blood
• Antibody tests: body’s reaction to the infection
– Treatment:
• Drugs to reduce liver damage and boost immune
system (interferon)
• Liver transplantation
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• Cirrhosis: liver cells are damage and replaced by scar
tissue
– Complications:
• Spider angiomas: tiny clusters of red veins close to the
surface of the skin
• Ascites: fluid accumulation in the abdomen
• Jaundice (also called icterus): yellowish cast to the skin
• Palmar erythema: The palms of the hands turn red and
blotchy
• Xanthomas: Small fatty yellow lumps on eyelids,
hands, and elbows
• Steatorrhea: Feces contain excessive fat, causing them
to float
• Hepatomegaly: Enlarged liver
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• Varices: Complication of diseased liver
– Esophageal varices: Complication of the liver where
abnormally enlarged veins in the wall of the lower
esophagus develop when normal blood flow to the liver is
blocked, causing portal hypertension (increased blood
pressure in the portal vein of the liver)
– Gastric varices: Dilated blood vessels in the stomach
• Treatments:
– Medications for to control bleeding and hypertension (beta
blockers for hypertension, vasopressin and somatostatin
for GI bleeding)
– Surgery: Transjugular intrahepatic portosystemic shunt
(TIPS) procedure to place stent in the liver and reroute
blood flow, relieving pressure and stopping bleeding
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• Irritable bowel syndrome: Disorder of the motility
of the digestive tract
– The word “syndrome” means “group of symptoms”
– Cause unknown as it manifests several symptoms
without a single cause
– Treatments:
• Antispasmodics to slow bowel spasms
• Laxatives to treat constipation
• Antidepressants (stress management)
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• Inflammatory Bowel Disease: Group of disorders
that cause the intestines to become chronically
inflamed and swollen
• Ulcerative colitis: Ulcerated inflammation of the
top layer of the large intestine
• Pancolitis: Inflammation of the entire colon
• Crohn disease: Open sores affecting all areas of
the GI system
– Complications
• Stricture: A narrowing f part of the intestine
• Fistula: An abnormal opening or passageway
• Fissure: A crack in the anal skin
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– Treatments: Controlling inflammation, correcting
nutritional deficiencies, reducing symptoms
– Drug Treatments:
• Anti-inflammatories: Sulfasalazine (Azulfidine),
steroids (prednisone)
• Immune system suppressors: Imuran and 6mercaptopurine (6-MP)
• Antibiotics: Metronidazole (Flagyl)
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• Surgical Treatments:
– Stricturoplasty: Surgical repair of the stricture in the
bowel
– Small bowel resection: diseased portion of bowel is
removed and the two healthy ends are sewn together
(called anastomosis)
• Anastomosis can be dictated as “end-to-end” or
“side-to-side”
– Ileostomy: End of the small intestine (ileum) is
brought out through a surgical opening in the
abdomen (a stoma). Waste is expelled through a
bag (an ostomy bag)
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• Surgical Treatments (Continued):
– Colectomy: Part or all of the colon is removed
– Proctocolectomy: Entire colon and rectum are
removed
– Ileal Pouch Anal Anastomosis (IPAA): Colon and
rectum are removed and internal pouch is created
form the ileum (called a J pouch). The pouch is
attached to the anus so that waste can leave the
body through the anus and not through an ostomy
bag
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• Intussusception
– Intestinal obstruction in children
– Intestine folds upon itself like a telescope
– Can correct itself or be repaired surgically by pushing
“telescoped” sections back into place
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• Diverticular Disease: presence of diverticula
– Diverticulosis: the presence of diverticula
– Diverticulitis: inflammation of diverticula
– Treatments:
– Diet and lifestyle modifications
– Antibiotics to treat infection in the colon: Flagyl,
amoxicillin (Amoxil) or tetracycline (Sumycin)
– Surgically resecting diseased segments of bowel
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Diagnostic Studies and Procedures
• Laboratory Tests
– Blood Tests
• Alkaline phosphatase
• Serum amylase
• Serum bilirubin
• Serum lipase
• Total cholesterol
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– Model for End-Stage Liver Disease (MELD) score: A
score for allocating livers for transplantation in
patients with liver disease
– Stool studies
• Fecal fat test: Elevated levels indicate
malabsorption, enabling fat to pass into the
stool
• Fecal occult blood test: Checks for occult, or
“hidden,” blood in the stool
• Stool culture: Check for the presence of abnormal
bacteria in the digestive tract
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• Imaging Studies
– Upper GI Series: Also called “barium swallow,” it is
an x-ray examination of the esophagus, stomach,
and duodenum
• Esophagram: Examination of esophagus only
• Cine-esophagram: Rapid-sequence x-rays are
taken during swallowing process to get sequential
pictures of swallowing mechanism
– Gastric emptying study (GES): Evaluates the speed
at which food empties from the stomach and enters
the small intestine
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• Imaging Studies (continued)
– Lower GI series: An x-ray examination of the large
intestine, including the rectum. Also called “barium
enema”
– Hepatobiliary iminodiacetic acid scan (HIDA):
Examines the function of the liver, gallbladder, and
bile ducts. Also called cholescintigraphy. Tracer
injected and scanner placed over the body to track
its movement through the biliary tract
– Abdominal ultrasound: Used to diagnose gallstones
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• Endoscopic Procedures
– Esophagogastroduodenoscopy (EGD): “upper
endoscopy”: Endoscopic examination of the
esophagus, stomach, and duodenum
• Esophagoscopy: Examination of esophagus only
• Gastroscopy: Examination of stomach only
• Gastroduodenoscopy: Examination of duodenum
– Colonoscopy: Examination of the entire length of the
large intestine to help identify abnormal growths or
polyps using a colonoscope
• Sigmoidoscopy: Examination of the sigmoid colon
(lower part of the large bowel)
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• Endoscopic Procedures (Continued)
– Endoscopic retrograde cholangiopancreatography
(ERCP): Also called cholangiography, a procedure
using contrast dye in a retrograde direction in the
hepatobiliary ducts, along with x-ray images, to
evaluate and treat problems in the bile ducts,
gallbladder, and pancreas
– Magnetic resonance cholangiopancreatography
(MRCP): When MRI is used along with contrast dye
to examine these structures
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Insight
The Brain-Gut Axis
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