Ch. 2 Abdominal Pain, Nausea, and Vomiting

Question 1

H&P:

Small Bowel Obstruction

Answer 1

• Colicky abdominal pain
• Nausea
• Bilious vomiting
• Abdominal distension
• Hyperactive bowel sounds (early) or hypoactive bowel sounds (late)
• Adhesions from prior abdominal surgery

Question 2

Answer 2

Dx: simple SBO but tx necessary in order to avoid progression and potential complications (strangulation, bowel necrosis, sepsis, death)

Pt also presents with:

• dehydration (dry mucous membranes)
• pre-renal azotemia (high BUN-to-creatinine ratio)
• hypochloremic, hypokalemic, metabolic alkalosis as a result of volume losses from recurrent emesis 2/2 SBO

Question 3

What is the most common cause of SBO worldwide?

Answer 3

Hernias

Question 4

Howship-Romberg Sign?

Answer 4

Obturator hernia

Pain in medial aspect of thigh with abduction, extension, internal rotation of hip due to compression of obturator nerve

Question 5

4 cardinal signs of strangulated bowel

Answer 5

• Fever
• Tachycardia
• Leukocytosis
• Localized abdominal tenderness

Question 6

Most common causes of SBO?

Answer 6

Question 7

What laboratory tests should be obtained in the initial work-up for SBO?

Answer 7

• CBC
  
  • Elevated Hb and Hct seen in dehydration
  • BUN/creatinine > 20 –> prerenal azotemia (caused by decreased blood flow to kidneys)
• Chemistry panel
  
  • Hypochloremic hypokalemic metabolic alkalosis –> from repeated bouts of emesis
  • Leukocytosis –> raises possibility of an infectious etiology or bowel compromise
• Serum lactate
  
  • Elevated serum lactate –> ischemic bowel

Question 8

What imaging is recommended for an SBO?

Answer 8

Initial imaging should include an abdominal series, generally followed by an abdominal and pelvic CT with oral and IV contrast

Question 9

How do you differentiate large and small bowel on radiographs?

Answer 9

Small bowel has lines (plica circulares) going all the way through the bowel

Large bowel has lines (haustra) only 1/2 through the bowel

Question 10

How do you distinguish between post-op ileus and SBO?

Answer 10

In early post-op period, it is important to distinguish an obstruction, which occurs in less than 1% of those undergoing laparotomy, from an ileus.

After abdominal surgery, GI motility is reduced due to a number of factors including a stress-induced sympathetic response, the release of inflammatory mediators, and use of anesthetic/analgesic agents.

Post-op ileus (physiologic phenomenon)

1. Small intestine usually regains normal motility with first 24 hrs after surgery
2. Stomach takes 48 hrs
3. Colon can take as long as 3-5 days

Ileus usually presents with hypoactive bowel sounds/pain is dull and constant.

• NO AIR-FLUID LEVELS**

One should suspect SBO if bowel fxn initially returned and subsequently the pt developed obstructive symptoms or if bowel fxn has not returned 3-5 days post-surgery

• AIR-FLUID LEVELS**
• DILATED LOOPS OF BOWEL

Question 11

Mgmt:

Initial steps in mgmt of SBO

Answer 11

Patients with SBO are often significantly dehydrated:

Aggressive fluid resuscitation (isotonic IV fluid –> NS) + electrolyte repletion

Additionally, early placement of NGT to evacuate air and fluid –> gastric decompression will decrease nausea, vomiting, distention, risk of aspiration

Majority of pts with partial obstruction will NOT need surgery

In pts with complete obstruction, may manage conservatively for 12-24 hr, but if no clinical improvement, surgical intervention is warrented

**Avoid re-operation on early post-op SBO unless clear evidence of peritonitis or bowel compromise