pathophysiology chapter 36

Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.

CHAPTER 36 GASTROINTESTINAL

DISORDERS


COMMON MANIFESTATIONS OF GASTROINTESTINAL TRACT

DISORDERS • Dysphagia

• Difficulty in swallowing• Inability to initiate swallowing• Sensation that swallowed solids/liquids “stick” in esophagus• Pain with swallowing (odynophagia) may accompany


COMMON MANIFESTATIONS OF GASTROINTESTINAL TRACT DISORDERS

(CONT.)



(CONT.)• Dysphagia—Type I

• Problems in delivery of food/fluid into esophagus• Causes

• R/T neuromuscular incoordination • Normal sequence is altered or absent



(CONT.)• Dysphagia—Type I

• Symptoms• May cough and expel the ingested food/fluids through mouth

or nose• Aspirate when attempting to swallow• Worse with liquids than solids



(CONT.)• Dysphagia—Type II

• Problems in transport of bolus down esophagus • Causes

• Outpouchings of one or more layers (diverticula)• Disorder of smooth muscle function (achalasia)• Interference of peristaltic activity (neoplasms, strictures)



(CONT.)• Dysphagia—Type II

• Symptoms• Sensation food is “stuck” behind sternum• May have impaired passage of liquids



(CONT.)• Dysphagia—Type III

• Problems in bolus entry into stomach• Causes

• Lower esophageal dysfunction or lesion obstruction• Symptoms

• Tightness or pain in substernal area during swallowing process



DISORDERS (CONT.)



DISORDERS (CONT.)• Esophageal pain

• Heartburn (pyrosis)• Cause

• Reflux of gastric contents into esophagus• High acidic contents are an irritant to sensory afferent

nerve endings in mucosa• Causes spasms of esophageal muscle




• Heartburn (pyrosis)• Symptoms

• Substernal burning sensation that may radiate to neck or throat




• Chest pain (esophageal distention or obstruction)• Symptoms

• Similar to angina pectoris (radiates to neck, shoulder, arm, and jaw)

• Brought on by swallowing



DISORDERS (CONT.)• Abdominal pain

• May be first sign of GI tract disorder• Three types

• Visceral pain• Cause

• Stretching or distending an abdominal organ • Inflammation

• Symptoms• Diffuse, poorly localized• Gnawing, burning, or cramping




• Three types• Somatic pain

• Cause• Injury to abdominal wall, parietal peritoneum, root of

the mesentery of the diaphragm• Symptoms

• Sharp, intense pain• Well localized to area of irritation




• Three types • Referred pain

• Felt at a location distant from source of pain• In the same dermatome or neurosegment

• Symptoms• Sharp and well localized• May be felt in skin or deeper tissues




• Acute• Instantaneous onset• Perforated ulcer or ruptured organ

• Chronic• Diverticulitis• Ulcerative colitis



DISORDERS (CONT.)• Vomiting

• Forceful expulsion of gastric contents through mouth• Accompanied by nausea• Characteristics of vomitus may suggest nature of

disorder



DISORDERS (CONT.)• Vomiting

• Causes• Coordinated sequence of abdominal muscle contraction with

reverse esophageal peristalsis• Alterations in the integrity of GI tract wall (gastroenteritis)• Alterations in motility (obstruction)



DISORDERS (CONT.)• Intestinal gas

• Results from altered motility or lack of digestive enzymes• Belching

• Eructation of swallowed air



DISORDERS (CONT.)• Belching

• Causes• Motility disorder• Gastric outlet obstruction preventing passage of air

from stomach to small intestine




• Belching • Causes

• Swallowing of air• Bacterial and digestive action on intestinal contents• Diffusion from the blood• Neutralization of acids by bicarbonate in upper GI tract




• Abdominal distention• Causes

• Failure to adequately digest nutrients such as lactose• Excess gas resulting from defect in intestinal motility




• Flatus• Causes

• Increased amounts of gas produced by action of bacteria on gas-producing nutritional substrates (legumes, vegetables)



DISORDERS (CONT.)• Bowel pattern alterations

• Constipation• Small, infrequent, or difficult bowel movements• Causes

• Dietary (low in fiber)• Lack of exercise• Pathologic conditions (ex: diverticulitis, obstruction)


CHEMICAL DIGESTION



DISORDERS• Bowel pattern alterations

• Diarrhea• Increased frequency and fluidity of bowel movements caused

by decreased transit time in SI• Acute

• Acute infection• Emotional stress• Leakage of stool around impacted feces



DISORDERS (CONT.)• Bowel pattern alterations

• Diarrhea• Chronic

• Chronic GI tract infection• Alterations in motility or integrity of GI tract• Malabsorption• Certain endocrine disorder• Food allergy • Ingestion of irritants• Caffeine



DISORDERS (CONT.)• Pathophysiologic mechanisms

• Osmotic• Increased amounts of poorly, absorbed solutes in the

intestine• Secretory

• Due to toxins that stimulate intestinal fluid secretion and impair absorption



DISORDERS (CONT.)• Pathophysiologic mechanisms

• Exudative (mucus, blood, protein)• Results from inflammatory processes

• Diarrhea related to motility disturbances• Example: dumping syndrome


DISORDERS OF THE MOUTH

• Stomatitis• Inflammation of oral mucosa

• Causes• Pathogenic organisms• Trauma• Chemical irritants• Chemotherapy, radiation• Nutritional deficiencies


DISORDERS OF THE MOUTH (CONT.)

• Acute herpetic stomatitis • “Cold sores”• Signs and symptoms

• Fever• Pharyngitis• Prodromal tingling and itching• Vesicles on erythematous base that rupture, leaving a painful

ulcer


DISORDERS OF THE MOUTH (CONT.)

• Acute herpetic stomatitis• Treatment• Use adequate oral hygiene • Medications

• Antiviral meds (famciclovir, valacyclovir)


ESOPHAGEAL DISORDERS

• Gastroesophageal reflux disease (GERD) • Backflow of gastric contents into esophagus through LES• Inflammation caused by reflux of highly acidic material• Progression can lead to ulceration, fibrotic scarring,

strictures, Barrett esophagus


ESOPHAGEAL DISORDERS (CONT.)• Gastroesophageal reflux disease (GERD)

• Causes• Any condition or agent that alters closure strength of

LES or increases abdominal pressure• Fatty foods• Caffeine• Large amounts of alcohol• Cigarette smoking• Sleep position• Pharmacologic agents• Anatomic features (ex: hiatal hernia)


ESOPHAGEAL DISORDERS (CONT.)

• Esophagitis• Barrett esophagus

• Complication when columnar tissue replaces normal squamous epithelium of the distal esophagus

• Carries a significant risk for esophageal cancer



• Hiatal hernia• Defect in diaphragm when a portion of the stomach

passes through the diaphragmatic opening into the thorax

• Risk increases with age • Women more than men



• Hiatal hernia • Can be life threatening if large portion of stomach

becomes caught above diaphragm and becomes incarcerated

• Signs and symptoms• Similar to GERD• Heartburn• Chest pain• Dysphagia



• Hiatal hernia• Sliding hernia (most common)

• Portion of stomach and gastroesophageal junction slip up into thorax above diaphragm

• Paraesophageal hernia (rolling)• Part of greater curvature of stomach rolls through the

diaphragmatic defect• Mixed



• Mallory-Weiss syndrome• Bleeding caused by a tear in mucosa or submucosa of

the cardia or lower portion of esophagus• Tear is usually longitudinal• Primary cause is forceful or prolonged vomiting



• Mallory-Weiss syndrome• Other factors or contributions

• Excessive ingestion of alcohol and salicylates• Coughing• Straining during bowel movements• Trauma• Hiatal hernia• Esophagitis• Gastritis



• Esophageal varices• Complication of portal hypertension resulting from

alcoholic or posthepatitis cirrhosis• Affects more than half of cirrhotic patients

• 30% have variceal hemorrhage within 2 years of diagnosis• High mortality rate


INFLAMMATION OF THE STOMACH AND INTESTINES

• Gastritis• Acute

• Precipitated by ingestion of irritating substances• Example: alcohol and aspirin

• Signs and symptoms• Anorexia• Nausea• Vomiting• Postprandial discomfort• Hematemesis



(CONT.)• Gastritis

• Chronic• Helicobacter pylori is nearly always a factor

• Complications• Peptic ulcer disease• Atrophic gastritis• Gastric adenocarcinoma• Mucosa-associated lymphoid tissue lymphoma



(CONT.)• Gastroenteritis

• Inflammation of stomach and small intestine• Usually a result of another GI disorder• Acute is caused by direct infection of tract by pathogenic

virus or bacterial toxin • May be caused by imbalance in normal bacterial flora by

introduction of unusual bacteria (travel)



(CONT.)• Gastroenteritis

• Signs and symptoms• Diarrhea• Abdominal discomfort and pain• Nausea• Vomiting• Fever• Malaise

• Treatment• Replace fluid and electrolytes



(CONT.)• Peptic ulcer disease

• Causes• H. pylori• Stress• Smoking• Alcohol• Spicy foods• Smoking• Genetic



(CONT.)




• Gastric• Due to breakdown of protective mucous layer that prevents

diffusion of acids into gastric epithelia• Barrier of epithelial layer and slightly alkaline layer of mucus

interrupted with chronic irritations



(CONT.)




• Duodenal• Inappropriate excess secretion of acid• Increased basal activity of vagus nerve

• Stimulates pyloric antrum cells to release gastrin to act on gastric parietal cells to release HCl

• Results in high level of HCl



(CONT.)




• Treatment• H. pylori: antibiotics• H2 antagonists• Proton pump inhibitors • Sucralfate (forms protective coating over injured mucosa)• Smoking cessation • Avoidance of ASA and NSAIDs, caffeinated beverages,

alcohol, and irritating foods



(CONT.)


INFLAMMATORY BOWEL DISEASE

• Ulcerative colitis• Large ulcers form in mucosal layer of colon and rectum • Associated with increased cancer risk after 8-10 years of

disease• Hallmark symptoms are bloody diarrhea and lower

abdominal pain


INFLAMMATORY BOWEL DISEASE (CONT.)

• Ulcerative colitis• Treatment

• Corticosteroids• Salicylate analogs• Immunomodulating agents

• Azathioprine• Mercaptopurine



• Crohn disease• Affects proximal portion of the colon or terminal ileum• Inflammation of all layers of the intestinal wall resulting

from blockage and inflammation of lymphatic vessels• Suggestive findings are ulcerations, strictures, and

fistulas



• Crohn disease• Signs and symptoms

• Intermittent bouts of fever• Diarrhea• RLQ pain• May have RLQ mass, tenderness

• Treatment• Smoking cessation, drugs similar to ulcerative colitis


ENTEROCOLITIS

• Antibiotic-associated colitis (AAC) (also called Pseudomembranous enterocolitis)• Acute inflammation and necrosis of small and large

intestine • Caused by Clostridium difficile (exposure to antibiotics)• Signs and symptoms

• Diarrhea (often bloody), abdominal pain, fever, colonic perforation (rare)

• Treatment: stop current antibiotic (if possible), treat ischemia, oral antibiotics such as metronidazole or vancomycin


ENTEROCOLITIS (CONT.)

• Necrotizing enterocolitis (NEC)• Occurs in premature infants (<34 wk) and infants with

low birth weight (<5 lb)• Characterized by diffuse or patchy intestinal necrosis

with sepsis• Signs and symptoms

• Distended abdomen and stomach, intestinal perforation• Treatment: surgical with antibiotics



• Appendicitis• Obstruction by fecalith, inflammation• Signs and symptoms

• RLQ pain (“McBurney’s point”) (classic, but may be anywhere), nausea, vomiting, fever, diarrhea, RLQ tenderness, systemic signs of inflammation

• Treatment: immediate surgical removal



• Diverticular disease (diverticulosis)• Presence of diverticula in the colon• Results in low intake of dietary fiber• Signs and symptoms

• Diverticulosis—asymptomatic• Diverticulitis—fever, acute lower abdominal pain

• Treatment: antibiotics and surgery for complicated diverticulitis


ALTERATIONS IN MOTILITY

• Irritable bowel syndrome• Chronic (>3 months) functional disorder • Fluctuations in stool frequency and consistency (no

nocturnal diarrhea)• Cause: unclear but slow wave activity of bowel in

increased.• Often associated with anxiety or depression


ALTERATIONS IN MOTILITY (CONT.)

• Irritable bowel syndrome• Signs and symptoms

• Diarrhea or constipation or alteration of both, abdominal cramping pain, mucus in stool, nausea, bloating

• Treatment• Antidiarrheal agents, antispasmodic medications, increased

fiber in diet



• Intestinal obstruction• Mechanical

• Adhesions, hernia, tumors, impacted feces, volvulus, intussusception

• Functional• Conditions that inhibit peristalsis such as narcotics,

anesthesia, surgery, peritonitis, hypokalemia, spinal cord injuries



• Intestinal obstruction• Signs and symptoms

• Depend on site and duration: dehydration, vomiting, electrolyte depletion, constipation, abdominal distention

• Treatment• Surgical intervention or decompression with intestinal tube• If left uncorrected may cause wall edema, ischemia, and

necrosis leading to bowel gangrene, sepsis, and shock



• Volvulus• Twisting of bowel on itself causing intestinal obstruction

and blood vessel compression (ischemia)• Results from anomaly of rotation, ingested foreign body,

or adhesion; cannot always be determined• Common sites are cecum and sigmoid colon• Sudden, tight, twisting of bowel impedes blood flow to

bowel



• Volvulus• Impeded blood flow leads to gangrene, necrosis, and

perforation• Life-threatening condition• Signs and symptoms

• Depend on site and duration: dehydration, vomiting, electrolyte depletion

• Treatment• Varies according to severity and location: surgical

intervention or decompression



• Intussusception• Telescoping/invagination of a portion of bowel into

adjacent (usually distal) bowel causing intestinal obstruction

• Males more than females• Signs and symptoms

• Increased bowel sounds, abdominal pain, varies• Treatment: surgical treatment



• Hirschsprung disease• Familial, congenital disorder of the large intestine in

which the autonomic ganglia are reduced or absent• Occurs 1:5000 live births• Most commonly found in infants and children• Males more than females



• Hirschsprung disease• Signs and symptoms

• Profuse diarrhea, hypovolemic shock, intestinal perforation• Treatment

• Colonic lavage, surgical intervention


MALABSORPTION DISORDERS

• Failure of GI tract to absorb or normally digest one or more dietary constituents

• Causes• Enzyme abnormalities• Infection• Radiation enteritis

• Signs and symptoms• Diarrhea• Passage of inappropriately processed intestinal contents

• Types (celiac diseases, tropical sprue)


MALABSORPTION DISORDERS (CONT.)

• Celiac disease (celiac spruce) • Familial intolerance of gluten-containing foods• Leads to inflammation and atrophy of the intestinal villi• Impaired nutrient absorption

• Reduced surface area • Decreased brush border enzymes

• 2x increase for intestinal malignancy



• Celiac disease (celiac spruce)• Diagnosis

• Intestinal biopsy• Anti-tissue transglutaminase antibody (anti-ttg)• Immunoglobulin A (IgA) endomysial antibody

• Treatment• Gluten-free diet• Supplemental Fe, folate, B12, fat-soluble vitamins (A, D, E, K)



• Tropical sprue• Malabsorptive syndrome of unknown cause• Prevalent in equatorial countries (living/visiting)• Adults more than children• Etiology

• Mucosa of small intestine atrophies resulting in malabsorption along with B12 and folic acid deficiency



• Tropical sprue• Signs and symptoms

• Severe diarrhea with blood-tinged stools, abdominal distention, steatorrhea

• Treatment• Predictability depends on area• Antidiarrheals, prolonged antimicrobial therapy


MALABSORPTION DISORDERS AFTER SURGICAL INTERVENTION

• Dumping syndrome• Dumping of stomach contents into small intestine due to

impaired gastric emptying• Common after gastrectomy• Large volume of hyperosmolar food is dumped rapidly

into small intestine leading to increased bowel motility• Rapid absorption of large amount of glucose leads to an

excessive rise in plasma insulin


MALABSORPTION DISORDERS AFTER SURGICAL INTERVENTION (CONT.)



• Dumping syndrome• Signs and symptoms

• Diarrhea, abdominal pain, • Rapid fall in blood glucose level 1-3 hr after meal (rebound

hypoglycemia)• Treatment

• Eating small meals throughout day instead of large meals, carbohydrate restriction, medications to reduce bowel motility



• Short-bowel syndrome• Severe diarrhea and significant malabsorption • Develops after surgical removal of large portions of SI• Rapid transit time and reduced surface area for

absorption• Diminished ability to absorb H2O, electrolytes, protein,

fat, carbohydrates, vitamins, and trace elements



• Short-bowel syndrome• Signs and symptoms

• Diarrhea and malabsorption• Treatment

• Temporary or indefinite intravenous nutritional support


NEOPLASMS OF GI TRACT

• Esophageal cancer• Accounts for 1%-2% of all cancers• Men more than women• Survival rate of <20% in men older than 60 years• Risk factors

• Genetic, diet high in nitrosamine content, chronic severe reflux (Barrett esophagus), environmental, smoking, alcohol


NEOPLASMS OF GI TRACT (CONT.)

• Esophageal cancer• Prognosis: poor; spreads extensively to surrounding

organs• Very high degree of metastasis• Treatment

• Stent placement, tumor ablation through heat probe and laser



• Gastric carcinoma• Prevalence in Japan 10x higher than U.S.• Men > 30 years• Stages (early and advanced)

• Determined by penetration into major muscle layer of stomach, involvement of lymphatic system and surrounding organs

• Risk factors• H. pylori infection, genetic, dietary habits, environmental

factors, smoking



• Small intestinal neoplasms• Benign or malignant• Unusual

• Account for <5% GI tumors• > 50 years• Causes partial or complete obstruction

• Depending on extent and type



• Small intestinal neoplasms• Signs and symptoms

• Depends on type and extent; partial or complete obstruction of small bowel may occur

• Treatment• Surgical removal of tumor and affected portion of SI



• Colonic polyps• Any protrusion into the lumen of the GI tract• Benign or malignant• Signs and symptoms

• Usually none; may cause occult or gross bleeding, abdominal pain

• Treatment• Varies according to size, type, and location



• Colon cancer• Risk factors

• Increases after age 40• High-fat, low-fiber diet• Polyps, chronic irritation or inflammation



• Colon cancer• Warning signs

• Black, tarry, or pencil-shaped stool• Change in bowel habits• Urgent need to defecate on awakening in morning• Alternating constipation and diarrhea• Sensation of rectal fullness• Dull ache may be felt in rectum/sacral region



• Colon cancer• Prognosis

• Early detection, better prognosis• Depends on extent of tumor invasion, cell type, degree of

dysplasia, tumor genetics, presence or absence of metastasis• TNM classification used for metastasis



• Colon cancer• Treatment

• Surgical removal• Chemotherapy, radiation, or both

pathophysiology chapter 36

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