Exam 2 - Bowel Obstruction

Question 1

What is the difference between a partial and complete bowel obstruction?

Answer 1

Partial - fluid/air continue to pass

Complete - cessation of passage of stool or flatus

Question 2

What are the three major causes of bowel obstruction?

Answer 2

• Extrinsic/Extra-luminal (external to bowel)
• Intrinsic (within wall of bowel)
• Intraluminal (defect that prevents passage of GI contents)

Question 3

What is the pathophysiology behind a bowel obstruction?

Answer 3

Obstruction leads to bowel dilatation and retention of fluid within lumen proximal to obstruction, while distal to obstruction, bowel decompresses

Question 4

What is the pathophysiology behind the complications of a bowel obstruction?

Answer 4

Excessive dilatation can compromise vascular supply leading to poor perfusion which can result in complications of: Ischemia –> Necrosis –> Perforation

Question 5

What is the most common etiology/risk factor for a mechanical small bowel obstruction?

What are two other main causes?

Answer 5

Adhesions from prior abdominal/pelvic surgery

Hernia and Neoplasm

Question 6

What clinical presentation is associated with a small bowel obstruction?

Answer 6

• Abdominal pain (periumbilical, intermittent, “cramping”)
• Abdominal bloating/distention
• Anorexia
• Nausea/Vomiting
• Constipation
• Obstipation (inability to pass flatus or stool)
• Possible hematochezia, fever/chills

Question 7

Your patient presents with periumbilical, intermittent, “cramping” abdominal pain along with other symptoms which makes you concerned for a small bowel obstruction. Their pain has now become more focal and constant. What should you be concerned for now?

Answer 7

Peritonitis

Question 8

What may be found on physical exam, including red flags, in a patient with a small bowel obstruction?

Answer 8

• Lying motionless (red flag)
• Abdominal distention
• High pitched “tinkling” bowel sounds (early phase) or hypoactive/absent (late phase)
• Diffuse or localized abdominal tenderness
• Peritoneal signs (red flag)

Question 9

What will be seen on a supine and upright abdominal x-ray in a patient with a small bowel obstruction?

Answer 9

Dilated loops of bowel with air fluid levels

Question 10

Why would you obtain a chest x-ray in a patient with possible small bowel obstruction?

Answer 10

Look for free air under diaphragm consistent with a perforation

Question 11

What will be seen on a CT abdomen in a patient with a small bowel obstruction?

Answer 11

• Dilated proximal bowel with distal collapsed loops
• Bowel wall thickening > 3 mm
• Submucosal edema

Question 12

What is the non-surgical management of a small bowel obstruction?

Answer 12

• Admit with general surgery/GI consult
• NPO
• Volume resuscitation (IV fluids and electrolyte replacement/management
• Bowel decompression with NG tube
• Anti-emetics, Analgesics, +/- Antibiotics
• Serial clinical monitoring over next 2-5 days (improvement marked by decrease in distention, passage of flatus/stool, decrease in NG output)

Question 13

What are some indications for surgical exploration of a small bowel obstruction?

Answer 13

Complicated bowel obstruction (ischemia, necrosis, perforation)
- Evidenced by worsening pain, fever, tachycardia, leukocytosis, metabolic acidosis, peritonitis

Intestinal Strangulation

Worsening symptoms or unresolved symptoms with NG tube and bowel rest

Question 14

What are causes of intestinal strangulation?

Answer 14

• Strangulated hernia
• Volvulus
• Intussusception (rare in adults, almost always associated with a tumor)

Question 15

What is an ileus?

Answer 15

Hypomotility of GI tract in absence of mechanical bowel obstruction (loss of peristalsis)

Question 16

What is the most common cause of an ileus?

What are some other causes?

Answer 16

Postoperative abdominal surgery (results from inflammatory response to intestinal manipulation/trauma)

Use of hypomotility agents (opioids, antispasmodics, anticholinergics)

Question 17

How does a patient present clinical with an ileus?

Answer 17

Abdominal pain, distention, bloating, “gassiness”, nausea, vomiting, inability to tolerate PO (similar to SBO)

Question 18

What will be seen on a 3-way abdominal x-ray series in a patient with an ileus?

Answer 18

• Dilated loops of bowel BUT air is present in both small and large bowel.
• NO air fluid levels

Question 19

What is the management for an ileus?

Answer 19

• IV fluids and electrolyte replacement
• Pain management with NSAIDs (avoid narcotics)
• Bowel rest (NPO/clear liquid diet)
• Bowel decompression with NG tube if persistent nausea/vomiting

Question 20

What is the most common etiology of a large bowel obstruction?

What are some other common causes?

Answer 20

Adenocarcinoma (colon and rectum)

Volvulus (sigmoid), fecal impaction

Question 21

What is a volvulus?

Answer 21

Abnormal twisting of a portion of the GI tract, usually the intestine, which can impair blood flow

Question 22

What will be seen on an abdominal x-ray that is consistent with a large bowel obstruction?

Answer 22

Dilated bowel proximal to obstruction

Question 23

What are risk factors for sigmoid volvulus?

Answer 23

• Chronic constipation
• Redundant sigmoid colon
• Colonic dysmotility
• Hypomotility agents

Question 24

What diagnostic studies are considered for possible sigmoid volvulus?

Answer 24

• Upright abdominal x-ray
• CT scan
• Contrast enema (diagnostic and therapeutic)

Question 25

What is the management for sigmoid volvulus?

Answer 25

• Flex Sig to decompress and de-rotate

- Surgery to resect redundant sigmoid colon and prevent recurrence

Question 26

What diagnostic studies are considered for possible cecal volvulus?

Answer 26

• Upright abdominal x-ray (dilated cecum typically displaced medially superiorly)
• CT scan (diagnostic)

Question 27

What is the management of cecal volvulus?

Answer 27

Surgery