Small Intestine Flashcards

1
Q

What comprises the small bowel?

A

Duodenum, jejunum, and ileum

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2
Q

How long is the duodenum?

A

12 inches

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3
Q

What marks the end of the duodenum and the start of the jejunum?

A

Ligament of Treitz

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4
Q

What is the length of the small bowel?

A

6 meters

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5
Q

What provides blood supply to the small bowel?

A

Branches of the SMA

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6
Q

What are the plicae circulares?

A

Circular folds of mucosa in small bowel lumen

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7
Q

What are the major structural differences between the jejunum and the ileum?

A

Jejunum: long vasa recta, large plicae circulares, thicker wall
Ileum: shorter vasa recta, smaller plicae circulares, thinner wall

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8
Q

What does the terminal ileum absorb?

A

B12, fatty acids, bile salts

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9
Q

What is an SBO?

A

Small Bowel Obstruction.

Mechanical obstruction to the passage of intraluminal contents.

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10
Q

What are the signs and symptoms of SBO?

A

Abdominal discomfort, cramping, nausea, abdominal distention, emesis, high-pitched bowel sounds

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11
Q

What lab tests are performed with SBO?

A

Electrolytes, CBC, T&S, UA

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12
Q

What are the classic electrolyte findings with proximal obstruction?

A

Hypovolemic, hypochloremic, hypokalemic alkalosis

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13
Q

What must be ruled out on PE in patients with SBO?

A

Incarcerated hernia

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14
Q

What major AXR findings are associated with SBO?

A

Distended loops of small bowel air-fluid levels on upright film

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15
Q

What is a complete SBO?

A

Complete obstruction of the lumen usually paucity or no colon gas

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16
Q

What is the danger of complete SBO?

A

Closed loop strangulation of the bowel leading to bowel necrosis

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17
Q

What is a partial SBO?

A

Incomplete SBO; some colon gas

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18
Q

What is the initial management of all patients with SBO?

A

NPO, NGT, IVF, Foley

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19
Q

What tests can differentiate partial from complete SBO?

A

CT with oral contrast, small bowel follow-through

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20
Q

What are the ABCs of SBO?

A
  1. Adhesions
  2. Bulge (hernias)
  3. Cancer and tumors
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21
Q

What are other causes (not ABCs) of SBO?

A

GIVES BAD CRAMPS:
Gallstone ileus, Intussusception, Volvulus, External compression, SMA syndrome, Bezoars, Bowel wall hematoma, Abscesses, Diverticulitis, Crohn’s disease, Radiation enteritis, Annular pancreas, Meckel’s diverticulum, Peritoneal adhesions, Stricture

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22
Q

What is SMA syndrome?

A

SMA compresses duodenum, causing obstruction.

Seen with weight loss.

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23
Q

What is the treatment of complete SBO?

A

Laparotomy and lysis of adhesions

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24
Q

What is LOA?

A

Lysis Of Adhesions

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25
Q

What is the treatment of partial SBO?

A

Initially, conservative treatment with close observation plus NGT decompression

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26
Q

Intra-operatively, how can the level of obstruction be determined in patients with SBO?

A

Transition from dilated bowel proximal to the decompressed bowel distal to the obstruction

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27
Q

What is the most common indication for abdominal surgery in patients with Crohn’s disease?

A

SBO

28
Q

Can a patient have complete SBO and bowel movements and flatus?

A

Yes; the bowel distal to the obstruction can clear out gas and stool

29
Q

After a small bowel resection, why should the mesenteric defect always be closed?

A

To prevent an internal hernia

30
Q

What may cause SBO if a patient is on coumadin?

A

Bowel wall hematoma

31
Q

What is the most common cause of SBO in adults?

A

Post-operative adhesions

32
Q

What is the most common cause of SBO around the world?

A

Hernias

33
Q

What is the most common cause of SBO in children?

A

Hernias

34
Q

What are the signs of strangulated bowel with SBO?

A

Fever, severe/continuous pain, hematemesis, shock, gas in the bowel wall or portal vein, abdominal free air, peritoneal signs, acidosis (lactic acid)

35
Q

What are the clinical parameters that will lower the threshold to operate on a partial SBO?

A

Increasing WBC, fever, tachycardia, tachypnea, abdominal pain

36
Q

What is an absolute indication for operation with partial SBO?

A

Peritoneal signs, free air on AXR

37
Q

What classic saying is associated with complete SBO?

A

“Never let the sun set or rise on complete SBO”

38
Q

What condition commonly mimics SBO?

A

Paralytic ileus (AXR reveals gas distention throughout, including the colon)

39
Q

What is the differential diagnosis of paralytic ileus?

A

Post-operative ileus after abdominal surgery (usually resolves in 3-5 days); Electrolyte abnormalities (hypokalemia most common); Medications (anticholinergic, narcotics); Inflammatory intra-abdominal process; Sepsis or shock; Spine injury; Retroperitoneal hemorrhage

40
Q

What tumor classically causes SBO due to mesenteric fibrosis?

A

Carcinoid

41
Q

What is the differential diagnosis of benign tumors of the small intestine?

A

Leiomyoma, lipoma, lymphangioma, fibroma, adenoma, hemangioma

42
Q

What are the signs and symptoms of small bowel tumors?

A

Abdominal pain, weight loss, SBO, perforation

43
Q

What is the most common benign small bowel tumor?

A

Leiomyoma

44
Q

What is the most common malignant small bowel tumor?

A

Adenocarcinoma

45
Q

What is the differential diagnosis of malignant tumors of the small intestine?

A

Adenocarcinoma, carcinoid, lymphoma, sarcoma

46
Q

What is the workup of a small bowel tumor?

A

UGI with small bowel follow-through, enteroclysis, CT, enteroscopy

47
Q

What is the treatment for malignant small bowel tumor?

A

Resection and removal of mesenteric draining lymph nodes

48
Q

What malignancy is classically associated with metastasis to small bowel?

A

Melanoma

49
Q

What is Meckel’s diverticulum?

A

Remnant of the vitelline duct, which connects the yolk sac with the primitive midgut in the embryo

50
Q

What is the most common small bowel congenital abnormality?

A

Meckel’s diverticulum

51
Q

What is the usual location of Meckel’s diverticulum?

A

Within 2 feet of the ileocecal valve on the anti-mesenteric border of the bowel

52
Q

What is the major differential diagnosis for Meckel’s diverticulum?

A

Appendicitis

53
Q

Is Meckel’s diverticulum a true diverticulum?

A

Yes

54
Q

What is the incidence of Meckel’s diverticulum?

A

2%

55
Q

What is the gender ratio for Meckel’s diverticulum?

A

M:F = 2:1

56
Q

What is the average age at onset of symptoms of Meckel’s diverticulum?

A

Within the first 2 years of life, but can occur at any age

57
Q

What are the possible complications of Meckel’s diverticulum?

A

Intestinal hemorrhage (painless); intestinal obstruction; inflammation/perforation

58
Q

What are the signs and symptoms of Meckel’s diverticulum?

A

Lower GI bleeding, abdominal pain, SBO

59
Q

What is the most common complication of Meckel’s diverticulum in adults?

A

Intestinal obstruction

60
Q

What heterotopic tissue type is most often found in Meckel’s diverticulum?

A

Gastric mucosa, but duodenal, pancreatic, and colonic are also found

61
Q

What is the “rule of 2s” for Meckel’s diverticulum?

A
2% of patients are symptomatic
Found 2 feet from the ileocecal valve
Found in 2% of the population
Most symptoms occur by 2 years
Ectopic tissue found in 1 of 2 patients
Most diverticula are 2 inches long
2:1 = M:F
62
Q

What is the role of incidental Meckel’s diverticulectomy?

A

Most experts would remove in children (controversial in adults)

63
Q

What is a Meckel’s scan?

A

Scan for ectopic gastric mucosa in Meckel’s diverticulum.

Uses technetium pertechnetate IV, which is preferentially taken up by gastric mucosa.

64
Q

What is the treatment of a Meckel’s diverticulum that is causing bleeding and obstruction?

A

Surgical resection with small bowel resection, as the actual ulcer is usually on the mesenteric wall opposite the diverticulum

65
Q

What is the name of the hernia associated with incarcerated Meckel’s diverticulum?

A

Littre’s hernia

66
Q

In patients with guaiac-positive stools and a negative upper and lower GI workup, what must be ruled out?

A

Small bowel tumor.

Evaluate with enteroclysis.

67
Q

What is the most common cause of small bowel bleeding?

A

Small bowel angiodysplasia