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STEP Pathology > deck_5577305 > Flashcards

deck_5577305 Flashcards

1
Q

Main arterial supply of the GI

A

Cardiac output: 7000 mlCeliac artery 800 mlSMA: 800 mlIMA: 480 ml

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2
Q

Describe the SMA

A

It is responsible of giving the vascular support to pancreatico-duodenal area, small intestine and right colon. It arises approximately 1 cm below the celiac artery and runs toward the cecum, terminating as the ileo-colic artery.

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3
Q

A vast network of collateral blood vessel gives substantial protection from ischemia or infarction in a setting of segmental vascular occlusion

A
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4
Q

How do catecholamines affect splanchic circulation?

A

they are released in response to oligemic shock and cause vasoncontriction

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5
Q

How do Angio II and ADH affect splanchic circulation?

A

vasoconstriction

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6
Q

How do gastrin, CCK, andsecretinaffect splanchic circulation?

A

Vasodilation

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7
Q

T or F.Ischemic changes are more common in the small than in the large bowel

A

T.

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8
Q

What are some major categories of intestinal ischemia?

A

Decreased arterial supplyDecreased venous returnLow flow states (heart failure, hemorrhage, shock)

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9
Q

Depending on the layers affected, infarcts are classified as:TransmuralMuralMucosal

A
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10
Q

What are the main ischemic diseases of the GI tract?

A

•Ischemic colitis•Acute mesenteric ischemia•Chronic mesenteric ischemia•Venous mesenteric ischemia

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11
Q

What is the ultimate cause of ischemic colitis?

A

Lack of BLOOD FLOW to the mucosa

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12
Q

The main symptoms of ischemic colitis center around whether it is occlusive or non-occlusive. What are some main causes of non-occlusive ischemic colitisand how does it present?

A

May occur spontaneously or be caused byhypotension, cardiac failure, sepsis and areeither subclinical or produce mild symptoms

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13
Q

The main symptoms of ischemic colitis center around whether it is occlusive or non-occlusive. What are some main causes of occlusive ischemic colitisand how does it present?

A

Thrombosis or embolization of the mesenteric arteriesLigation of IMA during aortic reconstruction or colon resectionDiffuse disease of small vessels (diabetes mellitus, vasculitis)Venous outflow obstruction (intra-abdominal inflammatory processes, hypercoagulability states)InfectionsExtrinsic and intrinsic obstruction (tumor, adhesions, volvulus, rectal prolapse)

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14
Q

The outcome of ischemic colitis depends on what?

A

severity, extent, rapidity of onset, status of collateral circulation, ability of bowel wall to resist bacterial infection

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15
Q

Ischemic colitis most commonly affects the what areas?

A

Wateshed areasof colon that have limited collateral circulation suchas the splenic flexure and rectosigmoid area.Rectum is generally not involved.

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16
Q

Ischemic colitis(also spelledischaemic colitis) is a medical condition in which inflammation and injury of the large intestine result from inadequate blood supply. Although uncommon in the general population, ischemic colitis occurs with greater frequency in the elderly, and is the most common form of bowelischemia.

A

Causes of the reduced blood flow can include changes in the systemic circulation (e.g.low blood pressure) or local factors such asconstriction of blood vesselsor ablood clot. In most cases, no specific cause can be identifiedIschemic colitis can span a wide spectrum of severity; most patients are treated supportively and recover fully, while a minority with very severe ischemia may developsepsisand become critically,sometimes fatally, ill

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17
Q

How are pts. with mild ischemic colitis tx?

A

Patients with mild to moderate ischemic colitis are usually treated with IV fluids,analgesia, and bowel rest (that is, no food or water by mouth) until the symptoms resolve. Those with severe ischemia who develop complications such as sepsis, intestinalgangrene, orbowel perforationmay require more aggressive interventions such assurgeryandintensive care. Most patients make a full recovery; occasionally, after severe ischemia, patients may develop long-term complications such as astrictureor chroniccolitis

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18
Q

Mesenteric ischemiais a medical condition in which injury of thesmall intestineoccurs due to not enoughbloodsupply.It can come on suddenly, known as acute mesenteric ischemia, or gradually, known as chronic mesenteric ischemia

A

Acute disease often presents with sudden severe pain.Symptoms may come on more slowly in those with acute on chronic disease

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19
Q

How does AMI present?

A

Early abdominal pain without ileus (a painful obstruction of the ileum or other part of the intestine) Peritoneal signs only in advanced disease Not always bloodSigns and symptoms of chronic disease includeabdominal painafter eating,unintentional weight loss,vomiting, and being afraid of eating.

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20
Q

What are some causes of occlusive AMI?

A

Embolism generally coming from atherosclerotic plaques: Origin of SMA Aortic dissection Neoplasm Vasculitis

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21
Q

What are some causes of non-occlusive AMI?

A

significant reduction in mesenteric flow secondary to cardiac failure or hypovolemic shock

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22
Q

T or F. AMI is a medical or surgical emergency

A

T.Delay in the diagnosis and treatment may result in bowel necrosis

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23
Q

How is AMI diagnosed?

A

X-ray, CT showing thickened bowel wall, ileus, and portal vein gasMRIAngiography (70-100% sensitive; 100% specific)

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24
Q

What are the risk factors for AMI?

A

Risk factors includeatrial fibrillation,heart failure,chronic renal failure, beingprone to forming blood clots, and previousmyocardial infarction

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25
Q

Three progressive phases of mesenteric ischemia have been described:Ahyper activestage occurs first, in which the primary symptoms are severe abdominal pain and the passage of bloody stools. Many patients get better and do not progress beyond this phase.Aparalyticphase can follow if ischemia continues; in this phase, the abdominal pain becomes more widespread, the belly becomes more tender to the touch, and bowelmotilitydecreases, resulting in abdominal bloating, no further bloody stools, and absent bowel sounds on exam.Finally, ashockphase can develop as fluids start to leak through the damaged colon lining. This can result inshockandmetabolic acidosiswithdehydration,low blood pressure,rapid heart rate, and confusion. Patients who progress to this phase are often critically ill and requireintensive care.

A
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26
Q

Thumb printing represent edema of lamina propria

A
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27
Q

What is this showing?

A

Ischemic intestines (code phrase= ‘dusky bowel’-May be salvageable, but the phrase is often used forinfarcted bowel that needs surgical removal)

28
Q

How does ischemic colitis present histologically?

A

•Superficial mucosal necrosis•Hyalinized lamina propria•Withered or atrophic crypts•Pseudomembranes•Chronic ulcers and strictures

29
Q

What is this showing?

A

Pseudomembrane in ischemic bowel

30
Q

What is this?

A

Pseudomembranous colitis

31
Q

What is Pseudomembranous colitis?

A

Pseudomembranouscolitis, also called antibiotic-associated colitis or C. difficile colitis, is inflammation of the colon associated with an overgrowth of the bacterium Clostridium difficile (C. diff). This overgrowth of C. difficile is most often related to recent antibiotic use. (•Immuno­suppression is also a predisposing factor)

32
Q

How doesPseudomembranous colitis present histologically?

A

•Adherent layer of inflammatory cells and debris.•The surface epithelium is denuded•The superficial lamina propria contains a dense infiltrate of neutrophils.•Superficially damaged crypts are distended by a mucopurulent exudate that forms an eruption reminiscent of a volcano.These exudates coalesce to form pseudomembranes.Lamina propria will not show hyalinization like ischemia

33
Q

Tenderness and bleeding appear late in case of acute mesenteric ischemia

A
34
Q

Pain usually appears during the first hour after eating and last for two to three hours.Weight loss present in about 80 percent of patients as the result of food aversion.

A
35
Q

Frequently patients with chronic mesenteric iscehmiahave history of what?

A

underlying atherosclerotic vascular disease

36
Q

What are the main risk factors for mesenteric venous thrombosis?

A

hypercoagulable states, portal hypertension, abdominal infections, blunt abdominal trauma, pancreatitis, splenectomy and malignancy in the portal region.

37
Q

How does venous mesenteric ischemia affect the GI?

A

Venous thrombosis produces resistance in mesenteric venous blood flow, bowel wall edema, fluid efflux into the bowellumen, increased blood viscosity and finally compromise of the arterial blood support.

38
Q

What is ‘upper’ GI bleeding defined as?

A

above the ligament of Treitz

39
Q

What is obscure bleeding?

A

bleeding without a clear sourceObscure overt bleeding: macroscopic obscure bleedingObscure occult: microscopic obscure bleeding. This is a chronic bleeding frequently presenting as iron deficiency anemia

40
Q

What is Melena?

A

black, tarry, loose or sticky, malodorous stool caused by degraded blood in intestine and generally indicates an upper GI source, although it may originate in the right colon

41
Q

What is hematochezia?

A

bright red blood from the rectum. It may be mixed with stools and usually indicates a lower GI lesions. When hematochezia is caused by an upper GI source, it indicates a massive hemorrhage

42
Q

What is the most frequent source of GI bleeding?

A

acute upper GI bleed (Upper GI bleeding is five times more frequent than lower GI bleeding)

43
Q

How are acute upper GI bleeds managed?

A

In general the management include the following1:stabilization of hemodinamic status2: determine the source3:stop active bleeding4: prevent recurrent bleeding

44
Q

In case of GI bleeding the main aspects to investigate through the medical history include the following:

A

History of peptic disease,recent use of NSAID,alcohol or caustic ingestion,cirrhosis, aortic graft surgery,coagulopathies,cancer, recent nose bleed

45
Q

What things should be examined on physical exam for a GI bleed?

A

Hemodinamic stability,stigmata of cirrhosis,vascular lesions,hepatomegaly,lymph nodes,epigastrictenderness,rectal exam

46
Q

What are some common causes of upper GI bleeding?

A

•Peptic ulcers•Gastritis and duodenitis•Tumors•Vascular malformation•Esophagitis•Varices

47
Q

In gastric ulcer we always have to consider malignancy as part of the differential. These patient require a surveillance endoscopy to document ulcer’s healing.

A
48
Q

What is the cause in 16% of patients with upper GI bleeding?

A

Gastric erosions, defined as aBreak in themucosa that does not cross the muscularis mucosa Endoscopically less than 3-5mm and without significant depth

49
Q

How do esophageal varices form?

A

•Venous blood from the GI tract passes through the liver, via the portal vein, before returning to the heart.•Portal hypertension results in the development of collateral channels at sites where the portal and caval systems communicate.•These collateral veins allow some drainage to occur, but at the same time they lead to development of congested subepithelial and submucosal venous plexi within the distal esophagus and proximal stomach =varices

50
Q

What are the main causes of esophagel varices?

A

cirrhotic patients, hepatic schistosomiasis

51
Q

What areMallory Weiss tears?

A

lacerations in the region of the gastro-esophageal junction caused by retching with forceful gastric mucosa prolapseAccounts for 5-10 UGI bleeds

52
Q

Mallory-Weiss tears

A

History of vomitingUsually resolves with conservative managementBleeding from Mallory—Weiss tears stops spontaneously in 80 % to 90% of patients, and less than 5% of patients rebleedTreatment include hemodynamic stabilization and endoscopic treatment. Angiography or surgery are rarely required.

53
Q

What are some common GI vascular malformations?

A

•Vascular ectasias•Dieulafoi lesion•Gastric Antral Vascular Ectasia (GAVE)-Watermelon stomach

54
Q

Neoplasms represent ___% of UGI bleeds

A

2-5%

55
Q

Etiology of small-bowel bleeding

A
56
Q

What is the best procedure available to study small intestine mucosa?

A

Capsule endoscopyIt is extremely helpful in the investigation in patient with occult bleeding

57
Q

What is the most common cause of acute LGI bleed?

A

Diverticulosis and angiodysplasia

58
Q

What is the most common cause of chronic LGI bleed?

A

Hemorrhoids and neoplasia

59
Q

What is Diverticulosis?

A

Diverticulosisis the condition of havingdiverticulain thecolonthat are not inflamed. These are outpockets of the colonicmucosaand submucosa through weaknesses ofmusclelayers in the colon wall. They typically cause no symptoms.Diverticular diseaseoccurs when diverticula become inflamed, known asdiverticulitis, or bleed

60
Q

How common is diverticular bleeding?

A

3% of diverticulosis pts. with 70% of bleeding occuring from the right side

61
Q

How does diverticular bleeding present?

A

Acute, painless, maroon to bright red hematocheziaBleeding is often significant but willstop spontaneously in 70:80% of patientsand25-35% will have a recurrent episodeof bleeding

62
Q

What is theMost common cause of lower GI bleeding?

A

Diverticuli bleeding,from penetration of a colonic artery into the dome of a diverticula3:5 % of patient with diverticulosis will bleed. 10-35 % will rebleed.

63
Q

What is the tx of diverticular bleeding?

A

Include hemodynamic stabilization and endoscopic treatment. Angiography with embolization and surgery are the option in patients with persistent bleeding.

64
Q

What is angiodysplasia?

A

angiodysplasiais a smallvascularmalformation of thegut. It is a common cause of otherwise unexplainedgastrointestinal bleedingandanemia. Lesions are often multiple, and frequently involve thececumorascending colon, although they can occur at other places.

65
Q

What are some causes of angiodysplasia?

A

•Advanced age•Chronic renal failure•Osler-Weber-Rendu•Prior radiation therapy

66
Q

WHat is this?

A

Colon cancer should be always considered in the differential of lower GI bleeding.The most common presentation is occult GI bleedingAlways consider colon malignancy in patients older than 50 presenting with iron deficiency anemia.

STEP Pathology (80 decks)

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