Chapter 43: Small Intestine- SBO

Question 1

What is small bowel obstruction (SBO)?

Answer 1

Mechanical obstruction to the passage of intraluminal contents

Question 2

What are the signs/symptoms?

Answer 2

1. Abdominal discomfort
2. cramping
3. nausea
4. abdominal distention
5. emesis
6. high pitched bowel sounds

Question 3

What lab tests are performed with SBO?

Answer 3

Electrolytes, CBC, type and screen, urinalysis

Question 4

What are classic electrolyte/acid–base findings with proximal
obstruction?

Answer 4

• Hypovolemic
• hypochloremic
• hypokalemia
• alkalosis

Question 5

What must be ruled out on physical exam in patients with SBO?

Answer 5

Incarcerated hernia (also look for surgical scars)

Question 6

What major AXR findings are associated with SBO?

Answer 6

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

Question 7

Define complete SBO

Answer 7

Complete obstruction of the lumen

Question 8

What is the danger of complete SBO?

Answer 8

Closed loop strangulation of the bowel leading to bowel necrosis

Question 9

Define partial SBO

Answer 9

Incomplete SBO

Question 10

What is initial management of all patients with SBO?

Answer 10

• NPO
• NGT
• IVF
• Foley

Question 11

What tests can differentiate partial from complete bowel
obstruction?

Answer 11

CT scan with oral contrast

Question 12

What are the ABCs of SBO?

Answer 12

Causes of SBO:

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

Question 13

What is superior mesenteric artery (SMA) syndrome?

Answer 13

Seen with weight loss—SMA compresses duodenum, causing obstruction

Question 14

What is the treatment of complete SBO?

Answer 14

Laparotomy and lysis of adhesions

Question 15

What is the treatment of incomplete SBO?

Answer 15

Initially, conservative treatment with close observation plus NGT decompression

Question 16

Intraoperatively, how can the level of obstruction be determined in
patients with SBO?

Answer 16

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

Question 17

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

Answer 17

SBO due to strictures

Question 18

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

Answer 18

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

Question 19

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

Answer 19

To prevent an internal hernia

Question 20

What may cause SBO if patient is on Coumadin®?

Answer 20

Bowel wall hematoma

Question 21

What is the #1 cause of SBO in adults (industrialized nations)?

Answer 21

Postoperative adhesions

Question 22

What is the #1 cause of SBO around the world?

Answer 22

Hernias

Question 23

What is the #1 cause of SBO in children?

Answer 23

Hernias

Question 24

What are the signs of strangulated bowel with SBO?

Answer 24

1. Fever
2. severe/continuous pain
3. hematemesis
4. shock
5. gas in the bowel wall or portal vein
6. abdominal free air
7. peritoneal signs
8. acidosis (increased lactic acid)

Question 25

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

Answer 25

1. Increasing WBC
2. Fever
3. Tachycardia/tachypnea
4. Abdominal pain

Question 26

What is an absolute indication for operation with partial SBO?

Answer 26

1. Peritoneal signs
2. free air on AXR

Question 27

What classic saying is associated with complete SBO?

Answer 27

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

Question 28

What condition commonly mimics SBO?

Answer 28

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

Question 29

What is the differential diagnosis of paralytic (nonobstructive)
ileus?

Answer 29

• Postoperative ileus after abdominal surgery
  
  • (normally resolves in 3 to 5 days)
• Electrolyte abnormalities (hypokalemia is most common)
• Medications (anticholinergic, narcotics)
• Inflammatory intra-abdominal process
• Sepsis/shock
• Spine injury/spinal cord injury
• Retroperitoneal hemorrhage

Question 30

What tumor classically causes SBO due to “mesenteric fibrosis”?

Answer 30

Carcinoid tumor