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Clin Med III Unit 2 > 1 Bowel Obstruction > Flashcards

1 Bowel Obstruction Flashcards

1
Q

What is the definition of bowel obstruction?

A

Blockage of the bowel that occurs when the normal flow of intraluminal contents is interrupted

Can be either functional or mechanical

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2
Q

Which is more common - functional or mechanical bowel obstructions?

A

Mechanical

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3
Q

Bowel obstructions are considered complete if…

A

Fluid and air continue to pass

Complete = cessation of passage of stool and flatus

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4
Q

What are the 3 major categories of obstruct causes?

A

Extrinsic/extraluminal (external to bowel - adhesions, abscesses)

Intrinsic (within the bowel wall - ie strictures)

Intraluminal (defect that prevents passage of GI contents - ie fecal impaction)

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5
Q

Obstruction leads to ______ and ________ within the lumen proximal to obstruction

Distal to obstruction, the bowel _________.

A

Bowel dilation

Retention of fluid

Decompresses

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6
Q

What leads to continued distention of the bowel following obstruction?

A

Swallowed air and gas from fermentation of accumulated matter

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7
Q

Why do patients with bowel obstruction become dehydrated?

A

Edematous bowel wall leads to fluid sequestration

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8
Q

What is the pathophysiology following bowel obstruction?

A

Excessive dilation can compromise vascular supply —-> poor perfusion —> ischemia —> necrosis —> perforation

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9
Q

What will you see on xray if the bowel is perforated?

A

Free air under the diaphragm

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10
Q

______ bowel obstruction accounts for 80% of obstructions

A

Small bowel

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11
Q

Vascular supply to the small intestine is primarily via…

A

The superior mesenteric artery (SMA)

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12
Q

What is the role of the small intestine

A

Digestion and absorption

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13
Q

Small intestine is subdivided into what three sections?

A

Duodenum —> Jejunum —> ileum

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14
Q

What is the most common cause of small bowel obstruction?

A

ADHESIONS (~65-75%) from prior abdominal or pelvic surgery

Ex: appendectomy, GYN surgery, bowel surgery

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15
Q

Other causes of SBO besides adhesions

A

Hernia (10-20%)

Neoplasm (10-20%) - primary or metastatic

Less common:
Intestinal inflammation or abscess
Strictures
FB ingestion
Intussusception
Volvulus
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16
Q

Type of SBO that is more specific to peds

A

Intussusception

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17
Q

What history questions should you ask when working up a potential SBO?

A

HAVE YOU EVER HAD ANY ABDOMINAL OR PELVIC SURGERY (risk greater with time)

Personal/Family Hx of cancer

Hx of hernia

N/V/D, constipation, hematochezia (and for how long)

Is the pain getting worse or better

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18
Q

Clinical presentation of SBO

A

Abdominal pain +/- fevers/chills
• Initially may be periumbilical, intermittent, cramping
• More focal and constant = bad (peritonitis)

Abdominal bloating/distention

Anorexia

N/V

+/- hematochezia

Constipation

Obstipation

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19
Q

Why is obstipation a bad sign in a patient?

A

Indicates progression of SBO, potential complete obstruction if they can’t pass flatus

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20
Q

Physical exam findings for SBO

A

+/- fever, tachycardia, hypotension, shock*

Mild/moderate distress, potentially lying motionless*

+/- decreased skin turgor, dry mucous membranes (if dehydrated)

Abdominal exam - do full exam!
• Inspection - note any distension, scars, hernias
• Auscultation - high pitched tinkling bowel sounds or hypoactive/absent
• Percussion - tympany on percussion b/c of air
• Palpation - diffuse or localized abdominal tenderness

Peritoneal signs* - guarding, rigidity, rebound tenderness (all red flags)

DRE - gross or occult blood, fecal impaction, or rectal mass possible

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21
Q

What are the red flag findings on physical exam when working up a potential SBO?

A

Signs of SHOCK

Lying motionless (moving hurts too much)

Hypoactive or absent bowel sounds

Peritoneal signs - guarding, rigidity, rebound tenderness

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22
Q

DDx for SBO

A

Abdominal medical or surgical conditions
• Medical = vomiting before pain
• Surgical = pain before vomiting

Non-obstructive motility issues

Ileus

LBO

Cecal volvulus

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23
Q

What labs do you want to order for a SBO?

A

CBC (+/- H/H, Leukocytosis, anemia)
CMP (+/- elevated BUN/Cr, electrolyte abnormalities)
Amylase/lipase
UA (+/- elevated specific gravity)
Lactate/LDH
Plain abdominal films (supine and upright)
CT scan

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24
Q

What will you see on plain film xrays for SBO?

A

Dilated loops of bowel with air fluid levels****

Proximal bowel dilation with distal bowel collapse

CXR to look for free air consistent with perforation

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25
What will CT scan show for SBO?
Dilated proximal bowel with distal collapsed loops Bowel wall thickening >3mm Submucosal edema
26
If xray or CT are contraindicated (ie pregnancy, kidney disease), or if you need further assessment, you should consider...
Abdominal US CT/MR enterography (more helpful for IBD) UGI/Small bowel follow through IF VERY HIGH SUSPICION, CALL SURGERY and let them decide on imaging
27
How do you manage a patient with SBO?
Admit Consult surgery/GI Trial of non-operative management Serial clinical monitoring over next 2-5 days, looking for improvement as evidenced by dec distention, passage of flatus/stool, dec NG output
28
What does non-surgical management of a SBO patient entail?
NPO (in case surgery but also anorexia) Volume resuscitation Electrolyte monitoring/replacement Bowel decompression with NG tube Anti-emetics (Phenergan, Zofran) Analgesics +/- Abx +/- Gastrograffin (GI, not us)
29
Indications for surgical exploration in patients with SBO
``` Complicated bowel obstruction (ischemia, necrosis, perforation), as evidenced by: • Worsening abdominal pain • Fever • Tachycardia • Leukocytosis • Metabolic acidosis • Peritonitis ``` Intestinal strangulation Worsening Sx or unresolved Sx with NG tube and bowel rest
30
What are some signs of peritonitis?
Patients LOOK sick Lie still to minimize discomfort Hypoactive/absent bowel sounds Peritoneal signs Significant pain with light palpation/bumps
31
Intussusception is rare in adults, and if found is almost always associated with...
A tumor
32
Compromised blood flow secondary to SBO can lead to complications of...
Ischemia Necrosis Perforation
33
Hypomotility of GI tract in absence of mechanical bowel obstruction
Ileus
34
Ileus is often secondary to ___________
Postoperative abdominal surgery > risk with open and lower GI surgery
35
Why do surgical patients get an ileus?
Results form inflammatory response to intestinal manipulation and trauma
36
When is a post-op ileus considered pathologic?
If no return of bowel function 4-6 days postoperatively May need TPN at this point
37
What else can cause an ileus besides surgery?
Use of hypomotility agents ie opioids, antispasmotics, anticholinergics
38
How does an ileus appear on supine/upright abdominal films?
Dilated loops of bowel but air present in both small bowel and colon No air fluid levels b/c not an obstructive process
39
How do you manage an ileus?
Supportive care with IVF, Lyte replacement Pain mgmt (but AVOID OPIOIDs - use NSAIDs) Bowel rest (NPO/CL diet +/- nutrition support) Bowel decompression with NG tube if persistent N/V Serial abdominal exams Ambulate
40
What are the subdivisions of the large intestine?
Cecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectum
41
Vascular supply to the large intestine
SMA and IMA
42
What is the primary role of the large intestine?
Absorbs water and electrolytes (right colon) and stores feces (left colon)
43
What are the different etiologies of LBO?
ADENOCARCINOMA Stricture due to diverticulitis/ischemia Volvulus - sigmoid and cecal IBD Fecal impaction Foreign bodies
44
What is the most common cause of LBO?
ADENOCARCINOMA Commonly of colon or rectum
45
What history questions are important to ask in cases of LBO?
Any current or hx of hematochezia, rectal bleeding, change in stool caliber Any personal/family hx of cancer LLQ pain with diarrhea (r/o diverticulitis) Recent frank bloody stool with diarrhea (r/o ischemia) How long? Acute or chronic (IBD) Chronic opioid use or chronic constipation?
46
Clinical presentation of LBO
+/- fever/chills Cramps abdominal pain, bloating, distention Constipation/obstipation +/- N/V Normal to quiet bowel sounds Abdominal tenderness +/- peritoneal signs Hematochezia DRE - occult blood, impaction, rectal mass?
47
What labs you gonna order for LBO?
CBC, CMP, UA, LDH/Lactate Plain abdominal films - supine and upright CXR to look for free air under diaphragm Gastrograffin enema if xray unclear CT scan
48
What will xray show for LBO?
Distended colon proximal to obstruction
49
How to manage partial LBO
Trial of conservative therapy Surgical consult NPO, IVF Antibiotics Decompression with NG tube if vomiting Avoid narcotics and anticholinergics
50
How to manage a complete LBO
Depends on the cause! Cancer - surgical resection Complete stricture - surgical resection Cecal volvulus - surgical resection (if >12cm) Sigmoid volvulus - sigmoidoscopy with reduction Intussusception - barium enema Fecal impaction - enema
51
Abnormal twisting of a portion of the GI tract, usually the intestine, which can impair blood flow
Volvulus
52
What are the two types of volvulus? Which is more common?
Sigmoid (more common) Cecal
53
Mean age for sigmoid volvulus
70 years
54
Mean age for cecal volvulus
33-53 years
55
Risk factors for sigmoid volvulus
Chronic constipation Redundant sigmoid colon Colonic dysmotility Hypomotility agents
56
Clinical presentation of sigmoid volvulus
Cramping abdominal pain N/V Pain before vomiting Constipation Distended tympanitic abdomen TTP
57
What diagnostic you gonna get for sigmoid volvulus?
Upright abdominal xray CT scan Contrast enema - both diagnostic and therapeutic***
58
Management of sigmoid volvulus
Flex sig to decompress and de-rotate Surgery to respect redundant sigmoid colon and prevent recurrence
59
Clinical presentation of cecal volvulus
Episodic pain to acute abdominal catastrophe Distended abdomen Tympanitic
60
What diagnostics you gonna get for cecal volvulus?
Upright abdominal xray - shows dilated cecum typically displaced medically and superiorly CT scan is usually diagnostic
61
How do you manage a cecal volvulus?
Surgical :-D
62
Upright abdominal xray shows dilated cecum displaced medically and superiorly
Cecal volvulus

Clin Med III Unit 2 (6 decks)

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