Lower Gastrointestinal Tract

Question 1

Most common and the most clinically significant congenital anomaly of the small intestine.

Two thirds pts < 2 yrs old

Outpouching of the gut on the antimesenteric border of the ileum, caused by persistence of the vitelline duct. Mostly asymptomatic.

Potential complications:
Bleeding, perforation, obstruction, diverticulitis

Answer 1

Merkel Diverticulum

Question 2

Complete occlusion of the intestinal lumen

Answer 2

atresia (neonatal intestinal obstruction)

Question 3

Narrowing, but do not complete occlusion, of the lumen

Answer 3

stenosis (neonatal intestinal obstruction)

Question 4

diagnosed on the basis of persistent vomiting within the first day of life. Surgical correction is usually successful.

Answer 4

stenosis and atresia

Question 5

The abdominal musculature fails to form, leading to birth of an infant with herniation of abdominal contents into a ventral membranous sac

Answer 5

omphalocele

Question 6

A portion of the abdominal wall fails to form altogether, causing extrusion of the intestines.

Answer 6

gastroschisis

Question 7

Caused by bacterial colonization of the surface epithelium with toxigenic strains of Escherichia coli and Vibrio cholerae

High mortality rate in infants from underdeveloped countries

Increased intestinal secretion stimulated by bacterial toxins and enteric hormones cause watery diarrhea and dehydration

Damage to the intestine is minimal

Answer 7

bacterial (toxigenic) diarhhea

Question 8

Common cause of infantile diarrhea
~50% of acute diarrhea in hospitalized kids < 2 yrs old
Associated with injury to surface epithelium

Answer 8

rotavirus viral gastroenteritis

Question 9

~30% of the epidemics of viral gastroenteritis in the USA
Patchy mucosal lesions (duodenum) and malabsorption
Symptoms resolve within 2 days

Answer 9

Norwalk viral gastroenteritis

Question 10

Triggered by decreased intestinal flow

Answer 10

ischemic bowel disease

Question 11

Most common type of ischemic bowel disease

Answer 11

acute intestinal ischemia

Question 12

Associated with atherosclerotic narrowing of major splanchnic arteries
Intermittent abdominal pain (intestinal angina)
Pain starts within 30 min after eating and last for a few hrs
May promote fibrosis and stricture formation, leading to intestinal obstruction

Answer 12

chronic intestinal ischemia

Question 13

A general term describing a number of clinical conditions that prevent the appropriate absorption of important nutrients by the GI tract.

Answer 13

malabsorption

Question 14

The most common clinical presentation is chronic diarrhea, and the hallmark of _____ is steatorrhea (excessive fecal fat content).

Answer 14

malabsorption

Question 15

Occur within lumen of small bowel.
Pancreatic enzymes and bile acids must be normally secreted into duodenal lumen. Prepares various nutrients to be taken up by small-bowel absorptive cells (i.e., adequate pH).

Answer 15

luminal phase of normal intestinal absorption

Question 16

Includes processes that occur in the cells and transport channels of the intestinal wall.

Answer 16

intestinal phase of normal intestinal absorption

Question 17

Reflects secretory insufficiency of pancreatic enzymes and bile acid

Answer 17

luminal phase of malabsorption

Question 18

Impaired mucosal function

Answer 18

intestinal phase of malabsorption

Question 19

Two types of clinical features of malabsorption

Answer 19

Specific: identifiable molecular defect causing malabsorption of a single nutrient (i.e., Disaccharidase deficiency, mainly lactase deficiency).

Generalized: a condition where absorption of several nutrient classes is impaired.

Question 20

characterized by

intolerance for their corresponding disaccharide

Answer 20

lactase deficiency

Question 21

Chronic disease, in which there is a characteristic
mucosal lesion of the small intestine and impaired
generalized nutrient absorption

Answer 21

celiac disease

Question 22

Damage to epithelial cells: flat mucosa, blunting of villi
Increased number of intraepithelial T cells
Increased plasma cells in lamina propria
Often duodenum and proximal jejunum

Answer 22

celiac disease

Question 23

Diarrhea, flatulence, abdominal pain, weight loss, and mucositis resulting from vitamin deficiencies

Answer 23

alimentary tract malabsorption

Question 24

Anemia from iron, pyridoxine, folate, and/or vitamin B12 deficiency
Bleeding from vitamin K deficiency

Answer 24

hematopoietic system malabsorption

Question 25

Osteopenia and tetany from calcium, magnesium, and vitamin D deficiency

Answer 25

musculoskeletal system malabsorption

Question 26

Amenorrhea, impotence, and infertility from generalized malnutrition
Hyperparathyroidism from protracted calcium and vitamin D deficiency

Answer 26

endocrine system malabsorption

Question 27

Purpura and petechiae from vitamin K deficiency
Edema from protein deficiency
Dermatitis and hyperkeratosis from deficiencies of vitamin A, zinc, essential fatty acids and niacin

Answer 27

epidermis malabsorption

Question 28

Peripheral neuropathy from vitamin A and B12 deficiencies

Answer 28

nervous system malabsorption

Question 29

Intraluminal obstruction
A segment of bowel protudes distally into a surrounding outer portion. Often in infants or young children.
May impair blood supply: infarction

Answer 29

intussusception

Question 30

Segment of gut twists on its mesentery, kinking the bowel and usually interrupting blood supply.

Answer 30

volvulus

Question 31

Fibrous scars caused by previous surgery or peritonitis may cause obstruction

Answer 31

adhesions

Question 32

Loops of small bowel may be incarcerated in an inguinal or femoral hernia. Vascular supply may be compromised

Answer 32

hernias

Question 33

Intestinal hamartomatous polyps
Mucocutaneous melanin pigmentation: perioral region, buccal mucosa, hands, feet, perianal, and genital areas.
Symptoms of bowel obstruction. However in ~25% pts diagnosis is based on hyperpigmentation.
Mutation in LKB1 tumor suppressor gene (encodes a serine threonine kinase)
Increased risk for cancers of breast, pancreas, testis, and ovary

Answer 33

Peutz-Jeghers Syndrome

Question 34

Arise from lymphoid tissue in mucosa/submucosa. Associated with celiac disease.
Persistent activation of T lymphocytes in the bowel may predispose to develop T-cell lymphomas

Answer 34

Intestinal Lymphoma

Question 35

Intestinal Lymphoma types

Answer 35

Mediterranean type:
Young men in underdeveloped countries
Most common sites: Duodenum and jejunum
Associated with a-heavy chain disease: proliferative disorder of intestinal B lymphocytes, which secrete the heavy chain of IgA without light chains.

Western type:
Children under 10 yrs of age and adults older than 40 yrs old
Most common site: Ileum
Intestinal obstruction, perforation, ocult bleeding.
When distal mets are present, 5-yr survival is <10%

Question 36

Submucosal nodules covered by intact mucosa. Larger tumors invade muscular layer and may cause fibrosis.

Answer 36

neuroendocrine tumors

Question 37

Most common cause of congenital intestinal obstruction

Dilation of colon due to the absence of ganglion cells and ganglia in the muscle wall and submucosa of the affected segment. Similar etiology as achalasia (esophageal motor disorder)

Usually in the wall of the rectum (diagnosis by biopsy)

Answer 37

Congenital Megacolon (Hirschsprung disease)

Question 38

Generic term for an inflammatory disease of the colon: exudative plaques on the mucosa

Associated with antibiotic therapy (alteration of fecal flora): Clostridium difficile. Produces toxins that damage the colonic mucosa

Answer 38

pseudomembranous colitis

Question 39

Acquired herniation of the mucosa and submucosa through the muscular layer of the colon. In reality, it is a false diverticulum.

Answer 39

diverticulosis

Question 40

Inflammation at the base of the diverticulum. Presumably from irritation caused by retained fecal material. 10-20% pts with diverticulosis at some point develop diverticulitis.

Most common symptoms: persistent abdominal pain and fever. Leukocytosis is the rule.

Answer 40

diverticulitis

Question 41

Chronic, segmental, transmural inflammation of the intestine

Mainly in the distal small intestine (ileum and cecum ~50% cases) but may involve any part of the GI tract. Only colon in ~20% cases.

Answer 41

Crohn Disease

Question 42

involvement of the intestine is discontinuous. Some segments are affected, some are normal.

Answer 42

sharply delimited lesions

Question 43

All layers of the bowel are typically involved with an inflammatory process (edema and fibrosis) with mucosal damage. Ulceration is the usual outcome of severe active disease.

Answer 43

transmural inflammatory disease

Question 44

mostly in the submucosa

Answer 44

presence of noncaseating granulomas

Question 45

Chronic superficial inflammation of the colon and rectum

Cause is unknown.

Answer 45

ulcerative colitis

Question 46

Three major features of ulcerative colitis

Answer 46

Diffuse disease: extends from the most distal part of the rectum to variable proximal distances.

Inflammation is generally limited to colon and rectum

Essentially a mucosal disease: no involvement of deeper layers of intestine.

Question 47

A phenotypic variant of FAP is ______ and include colonic and extracolonic lesions such as:
G.I. polyposis, stomach at ampulla of vater: polyps progress to colon cancer
Osteomas of jaws and long bones
Soft tissue tumors of skin

Answer 47

Garner Syndrome