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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
Q

What will CT scan show for SBO?

A

Dilated proximal bowel with distal collapsed loops

Bowel wall thickening >3mm

Submucosal edema

26
Q

If xray or CT are contraindicated (ie pregnancy, kidney disease), or if you need further assessment, you should consider…

A

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
Q

How do you manage a patient with SBO?

A

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
Q

What does non-surgical management of a SBO patient entail?

A

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
Q

Indications for surgical exploration in patients with SBO

A 
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
Q

What are some signs of peritonitis?

A

Patients LOOK sick

Lie still to minimize discomfort

Hypoactive/absent bowel sounds

Peritoneal signs

Significant pain with light palpation/bumps

31
Q

Intussusception is rare in adults, and if found is almost always associated with…

A

A tumor

32
Q

Compromised blood flow secondary to SBO can lead to complications of…

A

Ischemia
Necrosis
Perforation

33
Q

Hypomotility of GI tract in absence of mechanical bowel obstruction

A

Ileus

34
Q

Ileus is often secondary to ___________

A

Postoperative abdominal surgery

> risk with open and lower GI surgery

35
Q

Why do surgical patients get an ileus?

A

Results form inflammatory response to intestinal manipulation and trauma

36
Q

When is a post-op ileus considered pathologic?

A

If no return of bowel function 4-6 days postoperatively

May need TPN at this point

37
Q

What else can cause an ileus besides surgery?

A

Use of hypomotility agents ie opioids, antispasmotics, anticholinergics

38
Q

How does an ileus appear on supine/upright abdominal films?

A

Dilated loops of bowel but air present in both small bowel and colon

No air fluid levels b/c not an obstructive process

39
Q

How do you manage an ileus?

A

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
Q

What are the subdivisions of the large intestine?

A

Cecum

Ascending colon

Transverse colon

Descending colon

Sigmoid colon

Rectum

41
Q

Vascular supply to the large intestine

A

SMA and IMA

42
Q

What is the primary role of the large intestine?

A

Absorbs water and electrolytes (right colon) and stores feces (left colon)

43
Q

What are the different etiologies of LBO?

A

ADENOCARCINOMA

Stricture due to diverticulitis/ischemia

Volvulus - sigmoid and cecal

IBD

Fecal impaction

Foreign bodies

44
Q

What is the most common cause of LBO?

A

ADENOCARCINOMA

Commonly of colon or rectum

45
Q

What history questions are important to ask in cases of LBO?

A

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
Q

Clinical presentation of LBO

A

+/- 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
Q

What labs you gonna order for LBO?

A

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
Q

What will xray show for LBO?

A

Distended colon proximal to obstruction

49
Q

How to manage partial LBO

A

Trial of conservative therapy

Surgical consult

NPO, IVF

Antibiotics

Decompression with NG tube if vomiting

Avoid narcotics and anticholinergics

50
Q

How to manage a complete LBO

A

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
Q

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

A

Volvulus

52
Q

What are the two types of volvulus?

Which is more common?

A

Sigmoid (more common)

Cecal

53
Q

Mean age for sigmoid volvulus

A

70 years

54
Q

Mean age for cecal volvulus

A

33-53 years

55
Q

Risk factors for sigmoid volvulus

A

Chronic constipation

Redundant sigmoid colon

Colonic dysmotility

Hypomotility agents

56
Q

Clinical presentation of sigmoid volvulus

A

Cramping abdominal pain

N/V

Pain before vomiting

Constipation

Distended tympanitic abdomen

TTP

57
Q

What diagnostic you gonna get for sigmoid volvulus?

A

Upright abdominal xray

CT scan

Contrast enema - both diagnostic and therapeutic***

58
Q

Management of sigmoid volvulus

A

Flex sig to decompress and de-rotate

Surgery to respect redundant sigmoid colon and prevent recurrence

59
Q

Clinical presentation of cecal volvulus

A

Episodic pain to acute abdominal catastrophe

Distended abdomen

Tympanitic

60
Q

What diagnostics you gonna get for cecal volvulus?

A

Upright abdominal xray - shows dilated cecum typically displaced medically and superiorly

CT scan is usually diagnostic

61
Q

How do you manage a cecal volvulus?

A

Surgical :-D

62
Q

Upright abdominal xray shows dilated cecum displaced medically and superiorly

A

Cecal volvulus

Clin Med III Unit 2 (6 decks)

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