Small Intestine and Colon Pathology 1

Question 1

Define ileus

Answer 1

an intestinal obstruction caused by a loss of normal propulsive function of the bowel in the absence of mechanical obstruction

can be associated with abdominal surgery, trauma, peritonitis, mesenteric ischemia/infarction, various medications, intra-abdominal infection or gastroenteritis

Question 2

Define hernia

Answer 2

A defect in the wall of the peritoneal cavity allows the protrusion of a serosal-lined pouch of peritoneum called a hernia sac which bowel can enter and become strangulated

usually inguinal, femoral, umbilical or at abdominal surgical scars

Question 3

Define bowel adhesion

Answer 3

fibrous bands of scar tissue between bowel segments, abdominal wall or surgical sites

Question 4

define volvulus

Answer 4

complete twisting of a loop of bowel about its mesenteric base

most often ocurs in the sigmoid colon (followed by cecnum, small bowel, stomach, and transverse colon)

Question 5

Define intussusception

Answer 5

when a segment of bowel telescopes into the immediately distal segment

Question 6

Define stenosis

Answer 6

it’s a form of atresia in which the lumen is markedly decreased in caliber

this is usually associated with fibrous thickening of the wall

most common in esophagus, small bowel or anus but can occur anywhere

Question 7

Define atresia

Answer 7

when the lumen isn’t recanalized

Question 8

Define an omphoalocele

Answer 8

when closure of the ventral abdominal musculature is imcomplete and the abdominal viscera herniate into a ventral membranous sac in the umbilical cord

i don’t think i completely agree with this definition

Question 9

Define gastrochisis

Answer 9

all the layers of the abdominal wall fail to fuse in the midline, allowing the GI contents to be exposed

Question 10

What is a Meckel’s diverticulum

Answer 10

It’s a true diverticulum of the small bowel that occurs as a result of failed involution of the vitelline duct (which connected the developing gut to the yolk sac)

Rule of 2s: usually located on antimesenteric side of the ilumin 2% of the population, 2 feet from the valve, 2 inches long and 2x as common in males than females, symptoms occuring by age 2 (although most are asymptomatic)

Question 11

List the complications of Meckel’s diverticuli

Answer 11

ulceration (esp if it has ectopic gastric mucosa)
perforation
hemorrhage
fistula formation to the bladder
intussusception

Question 12

Describe the clinical presentation and pathologic abnormality in Hirchsprung’s disease

Answer 12

results when the normal migration of neural crest cells from cecum to rectum is arrested so the affected segment lacks ganglion cells in the enteric plexuses and you can’t get peristaltic contractions leading to functional obstruction and megacolon proximally

most commonly in the distal sigmoid colon and rectum (short segment disease)

patients typically present with failure to pass meconium in the neonatal period. infants and older children will present wiht obstructive constipation, abdominal distension and vomiting

Question 13

List the causes of ischemic bowel disease

Answer 13

acute arterial obstruction/thrombosis:
atherosclerosis
aortic aneurysm
hypercoagulable states
thromboembolism

mesenteric venous thrombosis: 
hypercoagulable states
portal hypertension
trauma
invasive noplasm
abdominal masses that compress portal drainage

hypoperfusion: cardiac failure, shock, dehydration, vasoconstrictive drugs, vasculitis

Question 14

Describe the bowel segments most likely to be affected by ischemia

Answer 14

segments located at the end of an arterial supply are most susceptible

include the splenic flexure, sigmoid colon and rectum

Question 15

What are the complications of transmural bowel necrosis?

Answer 15

transmural bowel necrosis can cause sepsis due to breakdown of the mucosal barrier with septic shock and death

can occur suddenly - present with abd pain, absent bowel sounds, N/V/D and melena

Question 16

Define angiodysplasia

Answer 16

it’s a lesion that consists of malformed submucosal and mucosal blood vessles typically in the cecum and right colon in older adults

Question 17

What is the clinical presentation of angiodysplasia?

Answer 17

lower GI bleeding

either acute and massive (hematochezia) or chronic and intermittent

Question 18

Define malabsorption

Answer 18

impaired absorption of nutrients

Question 19

What’s the clinical definition of diarrhea?

Answer 19

excessive increase in stool mass, frequency, or fluidity

typically greater than 200 g/day

clinically defined as over 3 loose stools per day. acute diarrhea is defined as diarrhea lasting less than 14 days. chronic diarrhea is diarrhea lasting over 4 weeks

Question 20

List the four kinds of diarrhea

Answer 20

1. Secretory diarrhea
2. Osmotic diarrhea
3. Malabsorptive diarrhea
4. Exudative diarrhea

Question 21

Describe the key pathologic findings in celiac disease.

Answer 21

you get an immune reaction that damages the surface epithelium of the small bowel

you’ll see intraepithelial lymphocytosis and vilous atrophy

on endoscopy you’ll see scalloped duodenal folds due to the villous atrophy

Question 22

What laboratory tests are helpful in establishing the diagnosis of celiac disease?

Answer 22

Test for IgA levels
Tissue Transflutaminase antibodies
Gliadin antibodies
Andomysial antibodies
Test for HLA-DQ2 or DQ8

Question 23

Define abetalipoporoteinemia

Answer 23

rare disorder caused by mutation in the microsomal triglyceride transfer protein that catalyzes the tranposrt of triglycerides, cholesterol esters and phospholipids from the enterocyte

so monoglycerides don’t get assembled into chylomicrons and the triglycerides just accumulate in the cytoplasm

failure to throvem diarrhea, steatorrhea. plasma ApoB absent. vit ADEK deficiencies, acanthocytes in the peripheral blood

Question 24

Define Whipple disease

Answer 24

a systemic infection caused by a gram positive actinomycete called Tropheryma whippelii

Question 25

Describe how Whipple disease is diagnosed

Answer 25

diarrhea, weight loss, malabsorption and abdominal pain - organism laden macrophages will accumulate in the lamina propria and mesenteric lymph nodes (also joints, heart valves, and brain)

definitive diagnosis with PCR on the tissue biopsy

Question 26

Describe the most common type of disaccharidase deficiency

Answer 26

lactase deficiency

Question 27

What is the most common cause of acute diarrhea

Answer 27

infectious enterocolitis

Question 28

What are the key clinical and pathological findings of C diff associated colitis.

Answer 28

clinical findings can range from mild diarrhea to fully developed pseudomembranous colitis to fulminant disease with perforation or toxic megacolon

toxins result in apoptosis of the colonic epithelium and can produce a mucosal surface exudate of necrotic epithelial cells, neutrophils, mucin and fibrin

Question 29

What is the key diagnostic test for C diff?

Answer 29

detect toxin producing strains of C diff typically with stool PCR assay

Question 30

Think back…What are the major causes of mechanical intestinal obstruction?

Answer 30

herniation
adhesions
volvulus
intussusception