Pathology of the Small intestine

list the common causes of obstruction in SI

hernia, intestinal adhesion, intussecption and volvulus

account for 80%

bowel obstruction distal to obstruction has a paucity of ____

gas

twisting of a loop of bowel about its mesenteric point of attachment

volvulus

volvulus results in what type of compromise

luminal and vascular

so youll have obstruction as well as infarction

x ray finding of coffee bean sign

volvulus

elderly have voluvlus in _______

YA have volvulus in _______

old = sigmoid

young =cecum

segment of intestine constricted by wave of peristalsis telescopes into immediately distal segment

intussectption

trapped and pulls mesentery along with it in subsequent peristalsis

classic triad of symptoms for intussception

colicky abodominal pain, biliuous vomiting, currant jelly stools

CT/US finding: target sign

adults: tumor

children: idiopathic, reactive lymphoid hyperplasia, meckel diverticulum, small bowel hematoma

causes of intussecption

abnormal protrusion of intraabdominal tissue through fascial defect in the abdominal wall

hernia

most hernias occur in the

groin

most frequent cause of intestinal obstruction worldwide

hernia

definitive treatment of hernia

surgery

surg procedures, infection or other causes of peritoneal inflammation such as endometriosis may result in

adhesions

fibrous bridges that can create closed loops throuhg which other viscera can slide and become trapped → obstrcution and strangulation

adhesions

mostly acquired but can be congenital in rare cases

adhesions

congential anomaly where bowel fails to canalize during weeks 3-7 of embryologic development.

results in obstruction adn ends in a blind loop

duodenal atresis

double bubble sign

duodenal atresia

polyhydramnios, bilious vomiting within first 24 hours of life

dudodenal atresia (compare with pyloric stenosis)

how is amniotic fluid produced

direct ransfer from maternal circulation

excretion of fetal urine by the kidneysk

kidney defects in utero result in

oligohydramnios

swalloing defects or absorption defects in utero leads to

polyhydramnios

outpuching of the bowel wall forming a true dicerticulum located in distal small bowel

meckel diverticulum

true diverticulum includes what layers

mucosa submucosa muscularis serosa

rule of 2s

in meckel diverticulum (diverTWOculum)

2% population

2% symptomatic

<2 years old

2:1 male to female

within 2 feet proximal to ileocecal valve

=< 2 inches long

2 types of mucosal lining (native ileal or heterotpic (gastric or pancreatic))

how are most cases of meckel diverticulum discovered

incidentally during surgery

acute inflammation of meckel diverticulum

meckel diverticulitis

same risk/complications of appendicitis

meckel diverticulitis

GI emergency in newbowns

inflammation and injury to intestinal mucosa due to gas producing bacteria that invade and release gas into bowel wall and portal venous system

NEC

neonatal necrotizing enterocolitis

where are most cases of NEC

very low birth weight infants born at less than 32 weeks gestation

immature intestinal tract and immunity

mucosal or full thickness necrosis

bowel perforation → DIC, shock, death

abdominal distension, bilious vomiting, bloody diarrhea

NEC

treatment of NEC

IV fluid, TPN, antibiotics, surgery

causes of ischemia/infarction in SI

arterial thrombosis

arterial emboli

venous thrombosis

generalized hypoperfusion

mucosal infarction most often occurs with

hypotension

mucosa is farthest from the blood supply

most due to emboli

sudden onset periumbilical pain out of proportion to findins

metabolic acidosis

acute mesenteric ischemia

most often due to athersclerosis

postprandial epigastric pain

avoid eating bc hurts → lose weight

chronic mesenteric ischemia

occlusion of the SMA often occurs with his

transmural infarction

loss of normal intestinal peristalsis, often due to surgery

adynamic ileus

abdominal distention, N/V, constipation, abdominal pain, lack of flatus

adynamic ileus

opitaes and anticholinergics are medication assoc causes of this

adynamic ileus

most receover with watchful wait and supportive care

other tc: iv fluid, electrolytes, avoid drugs that cause it, +- GI tube

adynamic ileus treatment

muation in gene encoding lactase (disaccharidase)

autosomal recessive

congenital lactase deficiency

symptoms aboate when milk exposure is temrinated

vili appear normal

congenital lactase deficiency

down regulation of lactase gene expression, common in native american african american and chinese population with increasing age

acquired lactase deficiency

can develop after infections and may resolve over time

abdominal fullness, flatulence, diarrhea

normal vili or injured from previous infection

acquired lactase deficiency

no source of ____________ in humans other than bacterial metabolism of carbohydrates

hydrogen gas

(post lactose hydrogen breath test)

lactose tolerance test

give them lactose, check and see if blood glucose goes up or not and also if there are symptoms

celiac disease is a type what hypersensitivity to gluten

type IV

most of the disease manifestation of celiac is related to

gliadin, alcohol soluble portion of gluten

how does gliadin results in tissue damage

is is deamidated by transglutaminase

demidated gliadin reacts with antigen presenting cells leading to stim of cd4+ lymphocytes that release cytokines that lead to tissue damage

increase in intraeptihelial lymphocutes marked atrophy r total loss of mili in more proximal small bowel (esp duodenum and prox jejunum), hyperplasia of crypts

celiac disease pathology

malabsorption as a result, may → microcytic anemia (iron def)

celiac

almost all celiac haplotype

HLA-DQ1 or HLA-DQ8

adults: chronic diarrhea, fatigue, may be asymptomatic

kids: irritable, abdominal distension, chronic diarrhea, failure to thrive, weight loss

celiac symptoms

associations and increased risk assoc with celiac

dermatitis herpetiformis

increased risk of t cell lymphoma and small bowel carcinoma

antibodies celiac disease

anti DGP, anti TTG anti EMA iga antibodies

iga def patietns → igg antibodies too

idiopathic celiacl like disease almost exclusively in people lving in or visting tropics

tropical sprue

I’d just die for biel

DIe: Duodenum Iron

Just For: Jejunum Folate

BIel: Ileum B12

rare systemic disease caused by trophermyma whipplei (gram pos rod bacteria)

whipple disease

any organ but most intestine mesenteric lymph nodes cns cardiac valves and joints

whipple disease

small bowel lamina propria with numerous macrophages filled with PAS postiive granules which are lysosomes stuffed with partially digested microorganism

macrophages compress lacteals and prevent chylomicrons from entering

fat malabsorption steatorrhea weight loss

whipple

rare autosomal recessive disease

loss of function mutation in MTP gene encoder

deficiency of apolopoprotein b-48 and apob100

acanthocytes seen on peripheral blood smear

abetalipoproteinemia

contracted dense RBC with irreg membrane projections that vary in length and width

acanthosis

seen in abetalipoproteinemia

low grade malignant neuroendocrine neoplasm

most in gi tract

carcinoid tumor

carcinoid tumors stain postivie for

synaptophysin

chromogranin

all gi sies: mucosa may be in tact or ulcerated and in the intestines the tumors may invade deeply to involve the mesentery

carcinoid tumor

yellow or tan in color and firm bc intense desmoplastic reaction →kinking of the bowel

carcinoid tumor

islands, trabeculae, strands, flansd, sheets of unifrom cells with scant pink granular cytoplasm and round to oval stippled nucleus

carcinoid

what do carcinoid tumors often secrete

serotonin

goes into portal venous system and metabolized by liver monoamine oxidase

can detect metabolite 5-HIAA in urine but will not get carcinoid syndrome

constellation of symptoms mediated by various humoral factors

flushing, bronchospasm, diarrhea, right sided cardiac valve fibrosis due to excess serotonin in pts with liver mets

alcohol adn stress can trigger

carcinoid syndrome

Be FDR

bronchospasm

flushing

diarrhea

right sided heart disease in carcinoid syndrome

most common tumor of appendic is a

carcinoid tumor

dilation of lumen of appendix by mucinous secretion usually in an appendix with dysplastic epithelium

mucocele

binign neoplasm, most common cause of mucocele

mucinous cystadenoma

malignant neoplasm

invasion through appendiceal wall → intraperitoneal seeding adn spread

resulting peritoneal implants may be mistaken for mucinous ovarian tumors

abdomen fills with semisolid mucin

mucinous cystadenocarcinoma

pseudomyxoma pertionei

abdomen fills with semisolid mucin in advance cases of mucinous cystadenocarcinoma

go make the appendicitis cards