GI: Small Bowel Flashcards

1
Q

what is duodenal atresia

A

congenital failure of duodenum to canalize

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2
Q

duodenal atresia is associated with what congenital disorder

A

Trisomy 21

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3
Q

what are 3 clinical features of duodenal atresia

A
  1. polyhydramnios
  2. distension of stomach and blind loop of duodenum (‘double bubble’ sign)
  3. bilious vomiting
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4
Q

What is Mechel Diverticulum

A

outpouching of all 3 layers of the

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5
Q

What causes Meckel diverticulum

A

failure of vitelline duct to involute

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6
Q

what is the ‘rule of 2s’

A

Meckel Diverticulum

  • 2% population
  • 2 inches long and located in small bowel within 2 feet of the ileocecal valve
  • present during 2 years of life with bleeding ( heterotopic gastric mucosa), volvulus, intussusception, or obstruction (mimics appendicitis)

MOST CASES ARES ASYMPTOMATIC

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7
Q

what is the most common congenital anomaly of the GI tract

A

Meckel Diverticulum

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8
Q

what is volvulus

A

twisting of bowel along its mesentery

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9
Q

Volvulus causes what

A

obstruction and disruption of blood supply with infarction

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10
Q

what is the most common location of volvulus

A
sigmoid colon ( elderly)
cecum ( young adults)
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11
Q

What is intussusception

A

telescoping of proximal segment of bowel forward into distal segment

  • telescoped segment is pulled forward by peristalsis, resulting in obstruction and disruption of blood supply with infarction
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12
Q

What is the most common cause of intussusception in children?

A

lymphoid hyperplasia (e.g., due to rotavirus)

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13
Q

What is the most common cause of intussusception in adults?

A

tumor

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14
Q

What is small bowel infaraction

A

small bowel is highly susceptible to ischemic injury

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15
Q

What are clinical features of small bowel infarction

A

abdominal pain
bloody diarrhea
decreased bowel sounds

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16
Q

when causes transmural infarction to occur in small bowel infarction

A

thrombosis/embolism of superior mesenteric artery or thrombosis of mesenteric vein

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17
Q

when causes mucosal infarction to occur in small bowel infarction

A

marked hypotension

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18
Q

what is lactose intolerance

A

decreased function of lactase enzyme found in brush border of enterocytes

19
Q

role of lactase

A

normally breaks down lactose into glucose and galactose

20
Q

clinical presentation for lactose intolerance

A

abdominal distension and diarrhea upon consumption of milk

- undigested lactose is osmotically active

21
Q

when do people become lactose intolerance

A
  1. congenital ( rare autosomal recessive disorder)
  2. acquired ( develops late childhood)
  3. temporary ( after small bowel infection- lactase is highly susceptible to injury )
22
Q

what is celiac disease

A

immune-mediated damage of small bowel villi due to gluten exposure
HLA-DQ2 and DQ8

23
Q

what is gluten present in and what is the pathogenic component

A

wheat and grains

gliadin

24
Q

how is gliadin a pathogenic component

A
  1. absorbed, gliadin is deamidated by tissue transglutaminase (tTG)
  2. deamidated gliadin is presented by MHC class II
  3. helper T cells mediate tissue damage
25
Q

children clinical presentation for celiac disease

A

abdominal distension
diarrhea
failure to thrive

26
Q

adult clinical presentation for celiac disease

A

chronic diarrhea and bloating

27
Q

how is the skin impacted with celiac disease

A

dermatitis herpetiformis : small, herpes-like vesicles on skin
- due to IgA deposition at tips of dermal papillae

28
Q

what is a laboratory finding for celiac disease

A
  • IgA antibodies against endomysium, tTG, or gliadin

- IgG abs present, useful for diagnosis in individuals with IgA deficiency

29
Q

what is seen in duodenal biopsy in celiac disease

A

flattening of villi, hyperplasia of crypts, and increased intraepithelial lymphocytes

  • damage more prominent in duodenum; jejunum and ileum are less involved
30
Q

What are late complications of celiac disease even with good diet restriction

A

small bowel carcinoma and T-cell lymphoma

31
Q

What is tropical sprue

A

damage to small bowel villi due to an unknown organism resulting in malabsorption

32
Q

what is the difference b/w tropical sprue and celiac disease

A

Tropical sprue has

  1. occurs in tropical regions ( caribbean)
  2. arises after infectious diarrhea and responds to antibiotics
  3. damage is prominent in jejunum and ileum ( secondary vitamin B12 or folate deficiency may ensue)
33
Q

What is whipple disease

A
  • systemic tissue damage characterized by macrophages loaded with Tropheryma whippelii organisms
  • partially destroyed organisms are present in macrophage lysosomes ( positive for PAS)
34
Q

where does Whipple disease occur

A

small bowel lamina propria (common)

  • synovium of joints ( arthritis)
  • cardiac valves
  • lymph nodes
  • CNS
35
Q

what is the pathogenesis of Whipple disease

A
  1. macrophages compress lacteals
  2. chylomicrons cannot be transferred from enterocytes to lymphatics
  3. results in fat malabsorption and steatorrhea
36
Q

What is abetalipoproteinemia

A

autosomal recessive deficiency of apolipoprotein B-48 and B-100

37
Q

clinical features of abetalipoproteinemia

A
  1. malabsorption - due to defective chylomicron formation ( requires B-48)
  2. Absent plasma VLDL and LDL ( require B-100)
38
Q

What is carcinoid tumor

A

malignant proliferation of neuroendocrine cells

low grade malignancy

39
Q

carcinoid tumor cells contain what

A

neurosecretory granules that are positive for chromogranin

40
Q

where does carcinoid tumor most likely occur

A
  • small bowel most commonly ( submucosal polyp-like nodule)

- arise anywhere along gut

41
Q

What do carcinoid tumor secrete

A

serotonin

- released into portal circulation and metabolized by liver monoamine oxidase (MAO) into 5-HIAA–> excreted in urine

42
Q

What is special about metastasis of carcinoid tumor to liver

A

serotonin bypass liver metabolism

- serotonin is released into hepatic vein, leaks into systemic circulation via hepato-systemic shunts

43
Q

metastasis of carcinoid tumor to liver can result in what other disease

A

Carcinoid syndrome and carcinoid heart disease