Chapter 11

Disorders of the GI Tract

Lecture 11

The Nature of DiseasePathology for the Health Professions

Thomas H. McConnell

Overview of Today’s Lecture

– Review of Digestive System

– General Signs and Symptoms of GI Disorders

– Oral Cavity Disease

– Esophageal Disease

– Stomach Disorders

– Vascular Diseases of the Small/Large Bowel

– Infectious Diseases of the Small/Large Bowel

– Malabsorption Syndromes

– IBD and IBS

– Neoplasms of the Small/Large Bowel

– Colonic Diverticulosis/Anorectal conditions

– Disease of the Appendix and Peritoneum

Figure from: Huether & McCance, Understanding Pathology, 5th ed.,

Elsevier, 2012

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Figure from: Porth, C.M., Essential Pathophysiology, 4th

ed., Elsevier, 2015

Review of the GI Tract Anatomy & Function

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Hormonal and Neural Signals Involved in Digestion

Table from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

The Peritoneum and Mesenteries

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Signs and Symptoms of GI Disorders

• Some terms to know the definitions of…– Anorexia– Nausea– Vomiting (emesis)

• Character is important (yellow/green, brown, coffee grounds, bloody (hematemesis)

– Dysphagia– Belching/flatulence– Diarrhea (Thinner, more frequent bowel movements)

• Dysentery (low-volume, bloody, painful)

– Constipation and Impaction

Causes of gastrointestinal bleeding

Two types of GI bleeding classified according to source:

- Upper GI: Everything from the 1st few cm of the duodenum to the esophagus- Lower GI: Below the 1st few cm of duodenum

**EVERY instance of GI bleeding should get immediate attention and be considered as a potential malignancy.

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Important terms associated with GI bleeding:

- Hematemesis- Hematochezia- Melena- Occult Bleeding (test?)

Interruptions of Peristalsis

• Ileus– Lack of peristalsis (intestinal paralysis)

– Associated with many conditions, e.g. post-op, intra-abdominal inflammation, intestinal ischemia, spinal cord injury, hypokalemia

• Mechanical Obstruction– Adhesions (surgery, infection)

– Intussusception (telescoping)

– Volvulus (twisting)

– Hernia• Incarcerated hernias

• Strangulated hernias

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of the Oral Cavity

Cleft Lip/Palate

Apthous ulcers

Herpesvirus

Cadidiasis (oral thush)

Squamous cell carcinoma

Diseases of the Oral Cavity

• Cleft Lip and Cleft Palate (Congenital)– Genetic and environmental factors– Mildest is split uvula– More serious lip or soft palate– Interferes with speech and

feeding– Associated with maternal

smoking and alcohol use– Folic acid before pregnancy

may decrease riskFigure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of the Oral Cavity– Apthous ulcers (canker sores)

• Small, painful, shallow

• Mainly in children and young adults

• Salt-water gargle is helpful

• May indicate more serious disease, e.g, Crohn

– Herpesvirus (multiple shallow ulcers)– Cadidiasis (oral thrush) (Candida albicans)

• Overgrowth of fungus when normal protective mechanisms are impaired

– Squamous cell carcinoma• On lip – usually better prognosis

• Floor of mouth – poorer prognosis

• Associated with poor oral hygiene, alcohol, tobacco

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of Oral Cavity – Teeth/Gums

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of the Oral Cavity

• Tooth and Gum Disease– Dental caries

• Erosion of tooth enamel (cannot be replaced!)

• Plaque (bacteria, dead cells, food debris, mucus)

• Tartar (calcified plaque)

– Gingivitis and Periodontitis• Inflammation of superficial gums

• Untreated may lead to periodontitis – deep inflammation of soft tissues around tooth root

• Infection of root – periapical abscess

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of the Oral Cavity - Salivary Glands

• Inflammation (sialadenitis)– Acute: streptococcus or mumps

– Chronic typically autoimmune, e.g., Sjogrens

• Pleomorphic adenoma– Usually benign

– Usually occur in major salivary glands, esp. parotid

– When occurring in minor salivary glands, more serious

Normal Esophagus

Diseases of the Esophagus

• Atresia– Absence or narrowing, with or without obstruction– Most common congenital defect– May accompany tracheoesophageal fistula

• Achalasia– Spasm of LES– Disappearance of autonomic ganglion cells– Autoimmune, immune reaction to viruses– Slowly progressive dysphagia and esophageal pain

Diseases of the Esophagus

• Hiatal hernia– Protrusion of part of stomach through

esophageal hiatus– May cause GER especially lying down

• Mallory-Weiss Syndrome– Tears or lacerations– Due to frequent vomiting/retching, e.g., in

bulimia

• Esophageal varices– Dilated veins, varicies (sing. Varix)– Almost always from cirrhosis of liver

Diseases of the Esophagus

• Esophagitis– Inflammation of esophagus– Painful swallowing (odynophagia)– Alcohol, smoking, reflux– When infectious, usually opportunistic

• Gastroesophageal reflux disease (GERD)– Incompetence of LES– Many causes– Heartburn (substernal pain) most common– When chronic, may cause Barrett esophagus

Barrett’s Esophagus

From: http://blogs.nejm.org/now/index.php/barretts-esophagus-2-2/2014/08/29/

Carcinoma of the Esophagus

Squamous cell carcinoma (50%)

-Arise from esophageal epithelium- Usually mid-upper esophagus- Risk factors:

- Male, African American- Heavy tobacco use; alcohol- Low fiber, high fat diet (a.k.a. US)

Esophageal Adenocarcinoma (50%)

-Usually lower esophagus (at GE junction)- B or T cell tumors-Originate in MALT- Risk factors:

- Male, Caucasian- **GE Reflux, e.g., Barrett’s- ObesityFrom:

http://blogs.nejm.org/now/index.php/barretts-esophagus-2-2/2014/08/29/

Disorders of the StomachFrom: Medline Plus

Acute nonerosive gastritis

- Acute erosive gastritis

Ulcers due to:- Stress: Curling- Brain trauma: Cushing

Chronic stress ulcers (90% due to H. pylori; some autoimmune)

Autoimmune gastritis – ab against parietal cells (no IF -> pernicious anemia

Zollinger-Ellison Syndrome – Pancreatic tumor secreting gastrin -> ulcerogenic

Chronic peptic ulcer of stomach

Disorders of the Stomach

Figure from: Marieb, Anatomy & Physiology, Pearson Education, 2016

Gastric adenocarcinoma (almost all):

-Arise from gastric epithelium- Genetic + Environmental- Risk factors:

- H. pylori- Smoked, pickled salt-preserved foods- Nitrites (preserved meat)- Low fiber, high fat diet (a.k.a. US)

Primary Gastrointestinal Lymphomas:

-Stomach most common site (60%)- B or T cell tumors-Originate in MALT- Risk factors:

- H. pylori- Malabsorption syndromes- Immunodeficiency

Vascular Diseases of Small and Large Bowel• Ischemic vascular disease

– Common in elderly with athersclerosis (celiac or mesenteric arteries)– Causes

• Thrombosis and embolism

• Vasculitis

• Volvulus

• Angiodysplasia– Small, twisted mass of blood vessels– Usually in colon or cecum

– Prone to bleeding• Hemorrhoids

– Varicies either within (internal) or outside (external) anal canal– From straining when defecating or venous stasis (pregnancy)– Blood will be bright red and ON stool (or toilet paper)

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Infectious Diseases of Small and Large Bowel

• Acute gastroenteritis– Inflammation of the stomach (fewer), or small/large bowel (more)

– Viruses and bacteria • More typical in developed countries

• usually produce only mild mucosal inflammation

– Protozoa and Parasites• More typical in developing nations

• Associated with more severe, chronic disease

• Viral Gastroenteritis (main cause of acute gastroenteritis in US)– Rotavirus – leading cause of diarrhea in small children (daycare)

– Norovirus (Norwalk) – older children/adults in close quarters where food is prepared for groups (think NORwegian CRUISELINE)

Infectious Disease of the Small and Large Bowel

Pseudomembranous colitisSalmonellosis; Typhoid fever

Traveller’s diarrhea

Amebic dysentery

Shigellosis (bacillary dysentery)

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Malabsorption Syndromes• Malabsorption

– Poor digestion or absorption of dietary substances

– Excess fecal excretion of nutrients (along with minerals and water)

– Effect of syndrome depends on which phase of digestion/absorption is affected:

• Luminal phase (within lumen of intestine)– Lack of pancreatic enzymes (esp lipase), e.g., cystic fibrosis

– Hepatobiliary disease (bile) -> steatorrhea

– Change in acid/base balance or microflora ecosystem

• Epithelial phase– disturbance of mucosal enzymes, e.g., lactase

– Inflammation

– Immune reaction to dietary content, e.g., gluten

• Lymphatic phase – Blockage of lymphatic ducts (affects fat absorption, mainly)

Malabsorption Syndromes

• Major effects of malabsorption syndromes– Hematopoietic (Vit B12, folic acid, vit K)

– Musculoskeletal

– Hormonal

– Skin

– Nerve

• Examples:– CHO Intolerance - Lactose intolerance

– Celiac sprue - Sensitivity to gluten (barley, rye, oats, wheat)

– Bacterial overgrowth syndrome

– Short bowel syndrome

– Chronic diseases

Inflammatory Bowel Disease

• Chronic inflammatory disease• T-cell mediated

• Suspect normal bacteria in genetically predisposed individuals

• Two major varieties – both immune-mediated inflammation

– Crohn Disease

– Ulcerative Colitis (C)

Inflammatory Bowel Disease

Mnemonic: Cathy Rohn is skipping across the wall on the way to grandma’s before she goes fishing.

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Irritable Bowel Syndrome

• Difficult to define in terms of pathology• Also called spastic colon, irritable colon, nervous

colon• No consistent anatomical/pathological lesions; it is a

functional disorder– Typically teens or young adults

– Abdominal pain, bloating, diarrhea, altered bowel habits

– Psychological problems are common

– Unlike IBD, weight loss, bleeding and vomiting do NOT occur.

Neoplasms of the Large and Small Bowel

• Overview– Far greater number of neoplasms occur in large

intestine than small intestine – Colon cancer is 2nd leading cause of cancer death in

US– Early detection is critical since

• Many benign lesions can be found early

• **Most colon CA arise from pre-malignant lesions called adenomatous polyps at least 10-15 years before becoming malignant

• Iron deficiency in adult males and post-menopausal females should always lead to investigation for intestinal CA.

Neoplasms of the Large and Small Bowel

• Neoplasms of the intestine fall into several major groups1. Non-neoplastic polyps (NOT pre-malignant)

• Hamartomatous; hyperplastic

2. Adenomatous polyps (Pre-malignant) • Tubular adenomas; Villous adenomas; Tubulovillous

3. Familial Adenomatous Polyposis (always leads to colon CA)

4. Colon cancer

5. Other tumors of the GI tract• Carcinoid; gastrointestinal stromal tumors (GIST)

Neoplasms of the Large and Small Bowel

• Non-neoplastic polyps (NOT pre-malignant)– The term ‘polyp’ refers to the shape of a growth – which may or

may not be a neoplasm– They are classified as based on two major criteria

• Stalk (pedunculated) or no stalk (sessile)• Non-neoplastic or Neoplastic (Benign or Malignant)

– Types • Hamartomatous polyps

– Non-neoplastic, disorganized tissue (a hamartoma)– Familial connection– Usually in children (Peutz-Jeghers syndrome)

• Hyperplastic polyps– Epithelial cell accumulation in mucosa (usually elderly)– Common– Sessile forms have malignant potential

Neoplasms of the Large and Small Bowel

• Adenomatous polyps (colonic adenomas)– Premalignant neoplasms of colon epithelium– High-fat, low-fiber diet has strong association– Males affected more often; over 65– About half in rectosigmoid colon (detected easily)– 10-15 years required for malignant transformation

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Neoplasms of the Large and Small Bowel• Familial Adenomatous Polyposis (always leads to colon

CA)– Autosomal dominant defect in APC gene (a tumor suppressor

gene)– **Left untreated 100% will develop into cancer, many before the

age of 30– Darkly pigmented retina, osteomas of mandible and long bones,

extra teeth, benign skin tumors and cysts

– Total colectomy is Tx

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Neoplasms of the Large and Small Bowel• Colon cancer

– 2nd leading cause of cancer death in US

– Almost all are adenocarcinomas (gland-forming)

– Early lesions are asymptomatic– Like adenomatous polyps, about half found in rectosigmoid

colon

– Invade colon wall directly and then metastasize (lymph nodes, liver (how?), lungs, and bones)

– Screening via: FOBT (not very sensitive) and sigmoidoscopy

Figures from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Neoplasms of the Large and Small

Bowel

Colon cancer – staging (American Joint Committee on Cancer)

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Colonic Diverticulosis

• Diverticulum – blind pouch with mouth opening onto the lumen of a space, e.g., colon

• Diverticulitis – inflammation of a diverticulum

• Acquired diverticula are more common than congenital

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Anorectal Conditions Are Common• In addition to hemorrhoids (discussed earlier)

– Anal fissures• Longitudinal tear in anal mucosa from straining

• Blood is bright red (where would this appear?)

– Anorectal Abscess• Usually in crypts (folds) in anal canal

• Arise from bacterial invasion – drainage required

– Anal fistula• Tubular tract from anus to other surface

• Surgery usually required

– Pilonidal cyst (sinus)• Cyst, pit, blind pouch in skin posterior to anus

• Almost exclusively in young, white males is a lot of hair in area

• Surgical drainage is usually performed

– Proctitis – Inflammation of anal mucosa; STI or IC

Diseases of the Appendix and Peritoneum

• Appendicitis– Acute inflammation of the appendix– Most common cause of acute

abdominal pain – teens/YA most often

– Several causes• Obstruction of lumen (hyperplasia of MALT in mucosa

• Fecalith, intestinal parasitic worms, foreign body

– Classic appendicitis• Epigastric or periumbilical pain

• Nausea, vomiting, anorexia

• RLQ pain and low-grade fever common

Figure from: McConnell, The Nature of Disease, 2nd ed., LWW, 2014

Diseases of the Appendix and Peritoneum

• Peritonitis– Inflammation of the peritoneum (usually acute)

– May be infectious or sterile

– Can develop as extension of any inflammatory condition of abdominal organs

– Infectious: direct spread of bacteria, e.g., gastric ulcer or apendicular perforation

– Sterile: chemical irritation, e.g, blood, pancreatic enzymes

– After healing my leave adhesions which can cause sequellae, e.g., intestinal obstruction

• Peritoneal carcinomatosis– Spread of carcinoma from abdominal or pelvic viscera

– Common in px with ovarian or pancreatic CA