Anatomy of GI bleeding Flashcards

1
Q

What is the function of the large intestine

A
  • Defence againt commensal bacteria
  • Absorption - H2O and electrolytes
  • Excretion of formed stool
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2
Q

Describe the anatomy of the colon

A
  • Caecum, appendix, Ascending, transverse, Descending, Sigmoid
  • Location: inferior to liver and Spleen
  • From Caecum to sigmoid: intraperitoneal - Secondarily retroperitoneal - intraperitoneal - secondarily retroperitoneal - intraperitoneal
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3
Q

What are Paracolic gutter

A
  • Spaces between the colon and the abdominal wall
  • peritoneal recesses on the posterior abdominal wall lateral to the ascending and descending colon respectively.
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4
Q

Describe the anatomy of the paracolic gutters

A
  • Left and right paracolic gutters
  • Between lateral edge of the ascending and descening colon
  • Postential sites for pus collection
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5
Q

What are the features of the colon

A
  1. Omental appendices
  2. Teniae coli - 3 longitudinal bands of thick SM
  • Runing from the caecum once the come together at the appendix to the distal end of the sigmoid colon
    3. Haustra - Sacculations cause by the contractions to teniae coli
  • Gives rise to the segmented appearance on colon
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6
Q

How does the colon look like one radiological appearance

A
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7
Q

describe the anatomy of the caecum and the appendix

A
  • location = both in right iliac fossa
  • postion of appendix is variable - but most commonly rectrocaecal
  • Appendiceal orifice - posteriomedial wall of caecum - Mcbuney’s point on anterior abdominal wall
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8
Q

What is the Mcburney’s point and wheres its location

A
  • Where the appendiceal orifice is found
  • 1/3rd of the way between Right Asis to umbilicus
  • Maximum tenderness when appendicitis
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9
Q

What is the anatomy of the sigmoid colon

A
  • Location - Left iliac fossa
  • Has a long mesentery - Sigmoid mesocolon - significant degree of movement
  • Disadvantage of long mesentery - Risk of Twisting around itself - Sigmoid volvulus
  • Results in bowel obstruction
  • Bowel at risk of infarction
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10
Q

What is the anatomy of the abdominal aorta

A
  • Midline Retroperitoneal structure
  • lies to left of IVC
  • 3 Midline branches - celiac trunk, SMA and IMA
  • Lateral branches- renal, gonads and body wall
  • Common illiac bifurcation - internal and external
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11
Q

What are all the levels of the abdominal aorta bifurcation

A
  • SMA - L1
  • IMA - L3
  • Celiac trunk - T12
  • Common illiac bifurcation - L4
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12
Q

What are all the branches of the SMA

A
  • Inferior pancreaticodoudenal
  • Middle colic artery
  • Right colic artery
  • ileocolic artery
  • Appendicular
  • Jejunal and ileal arteries
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13
Q

Describe the anatomy of Jejunal and ileal arteries

A

There both have a wasa rectae and arterial arcades

  • Jejunum has longer vasa rectae and larger but fewer arcades
  • Ileum has a shorter wasa resctae and small and many arcades
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14
Q

What are the branches of the IMA

A
  • Left Colic artery
  • Sidmoid arteries
  • Superior rectal arteries
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15
Q

what is the marginal artery of drummond

A

Arterial anatomoses between the Branches of the superior mesenteric artery and inferior mesenteric artery - obstruction in these vessels can help prevent intestinal ischaemia

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16
Q

what do the IMA and SMA look like on imaging

A
17
Q

What is the blood supply to the rectum and anal cana;

A
  • Rectum - Superior rectal artery - branch of IMA
  • Below pectinate line = internal illiac
18
Q

Describe the 2 veous system in the body

A
  • Hepatic portal venous system - Drains venous blood from absorptive parts of GI tract into liver for cleaning
  • Systemic venous system - Drains all other parts of organs and tissue into SVC or IVC
19
Q

What is the heptic porta vein made up on

A

Spleenic vein (foregut) and Superior mesenteric vein (Midgut Structures)

  • Inferior mesenteric vein (hindgut) drains into the spleenic vein
20
Q

Where are the important portal-system anastomosis

A
  • Skin around umbilicus - Connect para-umbilical veins and Epigastric veins
  • Rectum/anal canal - Inferior into iliac veins superior into IMV
  • Distal end of Eosophagus - inferior part drains into Hepatic portal vein and Superior part drains into azygous vein
21
Q

Venous drainage from the rectum and anal canal

A
22
Q

What is Portal hypertension

A
  • Hypertension of the HPV - due to Cirrhosis or Tumour compressing HPV
  • Leads to reversal of blood flow
  • Larger volume of blood to these areas can cause them to become varicosed
23
Q

Clinical presentation of portal hypertension

A
24
Q

What can the source of Haematemesis be

A
  • peptic ulcer in wall of stomach
  • Oesophageal varices