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GASTROENTEROLOGY SCE > Small Bowel > Flashcards

Small Bowel Flashcards

1
Q

Do patients with short bowel with an intact ileum and colon need long term enteral or parental therapy nutrition? Y/N

A

Rarely

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2
Q

Patients with a short bowel (loss of ileum) and retained functional colon. Gradual undernutrition dominates the clinical picture

  1. What length of small bowel left is required to avoid parenteral nutrition?
  2. What diet should these patients have?
A
  1. If 50cm of small intestine remains

2. High carbohydrate, low oxalate. The volume of food may increase diarrhoea

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3
Q

Jejunostomy patients:

  • fluid and electrolyte losses dominate clinical picture. Cannot adapt.
  1. Below what length of jejunum remaining do patients require IV fluids?
  2. Below what level of jejunum remaining do patients require TPN and fluids?
  3. If less than 200cm of jejunum remains, what may need to be avoided?
  4. If less than 200cm of jejunum remains, what may need to be given?
  5. How do you treat hypomagnesaemia in patients with a jejunostomy?
  6. How else can we reduce jejunal output?
A
  1. <100cm - when <100cm jejunum remains proximal to a jejunostomy more fluids are lost than taken orally. Jejunal mucosa is leaky and rapid sodium influx occur across it. If water or any solution with Na (<90mmol) is drunk then efflux of Na into lumen of bowel until a luminal sodium conc of 100mmol is reached
  2. <75cm
  3. Oral hypotonic fluids
  4. Glucose-saline supplementation (sodium conc of 100mmol approximating to the conc in jejunum fluid) is dipped to reduced stomal losses of sodium
  5. Treat sodium depletion, or or IV Mg and occasionally with oral 1-alpha-hydroxycholecalciferol
  6. Loperamide, or if bowel <100cm drugs that reduce gastric acid secretion (H2-antagonists, PPI, octreotide)
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4
Q

How do we measure bowel length?

A

From duodenojejunal flexure and can be made at surgery or with the use of an opisiometer tracing out the long axis of the bowel on a contrast study that shows all the remaining small bowel

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5
Q

When should patients be considered for referral of intestinal transplant?

A

Irreversible intestinal failure expected to die prematurely on parenteral nutrition

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6
Q

Levels of what are low and result in fast small bowel transit in jejunostomy patients?

A

Peptide YY and glucagon-like peptide 2 (GLP-2)

(The levels are high in those with a retained colon).

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7
Q

Where is the majority of fluid reabsorbed?

A

Upper jejunum.

Jejunum-colon patients can reabsorb unabsorbed fluid in their colon.

Jejunostomy patients lose much salt and water from their stoma

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8
Q

How much terminal ileum has to be resected to cause B-2 and fat malabsorption?

A

> 60-100cm

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9
Q

Why do you get magnesium deficiency in short bowel syndrome?

A

Reduced absorption because of chelation with unabsorbed fatty acids in the bowel lumen and to increased renal excretion

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10
Q

What is the most helpful measure of early sodium depletion?

A

Urine Na <10

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11
Q

What problems do unabsorbed long chain fatty acids cause in patients with jejuno-colon?

A

Reduce transit time
Reduce water and Na absorption
Worsen diarrhoea
Toxic to bacteria, so reduce carbohydrate fermentation
Increase oxalate formation = increased risk renal stones

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12
Q

What are the causes of confusion in a patient with short bowel?

A

Thiamine deficiency (Wernickes)
Low Mg
D-lactic acidosis
Hyper-ammonaemia

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13
Q

Why does D-lactic acidosis occur?

How do we treat it?

A

In patients with jejuno-colon
Colonic bacteria degrades fermentable carbohydrates to form D-lactate which is absorbed but not easily metabolised.
Get met acidosis with large anion gap

Avoid mono and oligosaccharides and encouraging more slowly digestible polysaccharides, thiamine, broad spectrum ABX, rarely may need to fast during parenteral nutrition

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14
Q

Why does hyper-ammonia occur in patients with short bowel?

How can it be corrected?

A
  • can’t detoxify ammonia by manufacturing CITRULLINE in the urea-cycle
  • Correct by giving ARGININE
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15
Q

Do gallstones form in patients with a short bowel?

A

Yes

Gall bladder stasis = biliary sludge = calcium bilirubinate stones

Some units perform prophylactic cholecystectomy when a large resection of small bowel is performed

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16
Q

What foods are high in oxalate (and thus should be avoided in patients with short bowel)

A 
Spinach
Rhubarb
Tea
Chocolate
Strawberries
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17
Q

Histological finding in coeliac for Marsh 1 classification

A

Lymphocytic infiltration (>40 per 100 surface enterocytes)

18
Q

Histological finding in coeliac for Marsh 2 classification

A

Crypt hyperplasia

Increases mitotic activity

19
Q

Histological finding in coeliac for Marsh 3 classification

A

Villous atrophy

A = partial
B= subtotal
C= total villous atrophy
20
Q

Histological finding in coeliac for Marsh 4 classification

A

Flat atrophic mucosa

Rare, may be irreversible

May be associated with development of T-cell lymphoma

21
Q

Describe the actions of lubiprostone

A

T2 chloride channel activator - increases luminal chloride secretion and thus fluid softening stool

22
Q

Actions of prucalopride

A

5HT4 agonist

23
Q

How does bisacodyl act

A

Through the mucosal afferent nerve fibres

24
Q

How do you calculate the stool osmolality gap

A

290 - 2(Na + K)

50-100 normal

25
Q

Causes of a low stool osmotic gap

A

VIPoma
Cholera
Gastrinoma

26
Q

Causes of a high osmotic gap in stool

A

Laxative abuse
Lactulose chronic pancreatitis
Whipples

27
Q

How does cholera cause secretory diarrhoea

A

Increases cAMP which increases channels activated in apical membrane = chloride release and fluid

28
Q

How is potassium absorbed in the small bowel?

A

Passive absorption

In the colon it is via active transport

29
Q

Where is GLP-1 and 2 secreted from

A

Enteroendocrine cells

30
Q

Describe the actions of GLP1 and 2

A

Slow GI transit

Reduce appetite

31
Q

Describe the mechanism of lactose intolerance

A

Lactase is a small intestine brush border enzyme that hydrolysed lactose to glucose and galactose.

Deficiency in a brush border membrane hydrolase results in intolerance

32
Q

Why does zollinger Ellison syndrome cause steatorrhoea?

A

High acid - low pH - reduced action of pancreatic lipase = steatorrhoea

33
Q

Where is copper primarily absorbed?

What are the possible features of copper deficiency?

Patient that have had what surgical procedure are at higher risk of copper deficiency?

A

Duodenum

Microcytic anaemia with normal iron studies, leukopenia

Roux-en-y as bypassing duodenum

34
Q

Where is magnesium absorption greatest?

A

Ileum

Jejunal absorption is increased by vitamin D

35
Q

Where is calcium absorbed

A

Duodenum and proximal jejunum

36
Q

The excess in bacteria in SIBO synthesise acetaldehyde which can cause what complication?

A

Liver injury leading to NAFLD

37
Q

Why is there an increased risk of oxalate renal stones in short bowel?

A

Increased unabsorbed fatty acids hat bind to calcium. Therefore less calcium for oxalate to bind to increasing free levels of oxalate which is absorbed and excreted in kidneys

38
Q

How does D-lactic acidosis occur?

What are the clinical signs?

How can we try and prevent it in patients with short bowel?

A

Increased fermentation of colonic simple carbohydrates causing increased delivery of glucose to colon where colonic bacteria ferment the carbohydrate and release D-lactic acid which is absorbed but not metabolised

Confusion, ataxia, slurred speech, sweats, inappropriate behaviour

Prevent by limiting simple sugars and providing complex carbohydrates

39
Q

Tropical spruce:

  1. Describe the endoscopic findings
  2. Are patients usually protected from a second wave? Y/N
  3. How may the patient present?
  4. What condition can it mimic?
  5. Treatment
A
  1. Villous atrophy and lymphocytic infiltrates
  2. Yes
  3. Malabsorption symptoms, ADEK deficiency
  4. Coeliac
  5. Tetracycline or septrin

Endemic in Asia, South America

Cause unclear

40
Q

Whipples disease:

  1. Cause and type of organism
  2. Symptoms
  3. How diagnosed
  4. Diagnostic findings
  5. Treatment
A
  1. T whipplei. Gram positive
  2. Neurology manifestations (40%), fever, diarrhoea, lymphadenopathy, joint pains, weight loss
  3. Small bowel biopsy, PCR
  4. Diffuse PAS positive macrophages
  5. Septrin - crossed blood brain barrier reducing risk of CNS relapse

Can be asymptomatic carrier with positive PCR and no symptoms

GASTROENTEROLOGY SCE (11 decks)

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