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MBBS 3: Surgery > Bowel Obstruction > Flashcards

Bowel Obstruction Flashcards

1
Q

What is a bowel/intestinal obstruction?

A

Interruption of the normal passage of bowel contents through the bowel, either due to functional or mechanical obstruction

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2
Q

What is an acute abdomen?

A

Sudden onset severe abdominal pain due to the presence of an abdominal pathology which if left untreated (within 72 hours), will result in patient morbidity and mortality.
- Requires rapid and specific diagnosis

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3
Q

Classification of bowel obstruction?

A

A. Anatomical
1. Small bowel obstruction
2. Large bowel obstruction

B. Pathological
1. Mechanical (dynamic) - peristalsis working again a mechanical obstruction
2. Functional (adynamic) - absence of peristalsis, without “obstruction” or non-propulsive peristalsis (pseudo-obstruction)

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4
Q

Symptoms of small bowel obstruction?

A

High
1. Early profuse vomiting, with dehydration
2. Minimal distension

Low
1. Predominantly central abdominal distension
2. Multiple central fluid seen

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5
Q

Symptoms of large bowel obstruction?

A
  1. Early and pronounced distension
  2. Mild pain
  3. Late vomiting and dehydration
  4. Proximal colon and cecum distended (competent ileo-cecal valve)
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6
Q

What is mechanical bowel obstruction?

A

physical barrier preventing movement of bowel contents

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7
Q

Exaples of mechanical intra-luminal bowel obstruction?

A
  1. Fecal Impaction (stools) – i.e. bed-ridden patients
  2. Gallstone ‘ileus’
  3. Foreign Body e.g bezoars, worms
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8
Q

Examples of intra-mural mechanical bowel obstruction?

A
  1. Masses- benign Vs malignant
  2. Inflammatory Strictures (TB / Crohn’s, diverticulitis, radiation colitis)
  3. Intestinal Atresia
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9
Q

Examples of extra-mural mechanical bowel obstruction?

A
  1. Intraperitoneal bands and adhesions
  2. Hernia
  3. Volvulus – sigmoid / cecum (more commonly sigmoid)
  4. Intussusception
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10
Q

Name 2 types of functional bowel obstruction?

A
  1. paralytic ileus
  2. pseudo obstruction
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11
Q

What is paralytic ileus?

A
  • hypo-mobility w/o obstruction : accumulation of gas & fluids
  • Failure of transmission of peristaltic waves due to NM failure (Myenteric (Auerbach’s) and submucosa (Meissner’s) plexuses
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12
Q

What are the causes of paralytic ileus?

A
  1. Post-operative (most common)
  2. Infection – intra-abdominal sepsis
  3. Reflex Ileus
  4. Metabolic – uraemia & hypokalaemia most common
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13
Q

What is pseudo obstruction?

A

Recurrent obstruction (usually colon) occurring without a mechanical cause or acute intra-abdominal disease

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14
Q

Examples of pseudo-obstructions?

A
  1. Small Intestinal Pseudo-obstruction (idiopathic or a/w familial visceral myopathy)
  2. Acute Colonic Pseudo Obstruction eg, Toxic Megacolon
  3. Chronic Colonic Pseudo Obstruction eg, Hirschsprung Disease
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15
Q

Pathophysiology of a bowel obstruction?

A
  1. Dilatation of bowel proximal to obstruction & collapse of distal bowel
    2, Hyper-peristalsis
    3
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15
Q

Pathophysiology of a bowel obstruction?

A
  1. Dilatation of bowel proximal to obstruction & collapse of distal bowel
  2. Hyper-peristalsis
  3. Strangulation
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16
Q

What is hyper peristalsis?

A
  1. Gas Accumulation - significant overgrowth of aerobic and anaerobic organisms from swallowed air(gas composition – O2 , CO2 , H2S & N2)
  2. Fluid Accumulation - impaired absorption from gut leading to sequestration of fluid in the bowel lumen (risk of dehydration and electrolyte imbalance)
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17
Q

What is strangulation?

A

Compromised venous return due to dilated bowel
- Increased capillary pressure
- Local mural distention due to fluid and cellular exudation
- Compromised artery supply -HAEMORRHAGIC INFARCTION
- Risk of translocation of intestinal bacterial and toxins into peritoneal cavity -PERITONITIS AND SEPTICEMIA
- When long segments of bowel are strangulated, sequestration of blood occurs in the strangulated segment -HYPOVALEMIC SHOCK

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18
Q

Presentation of a bowel obstruction?

A
  1. abdominal pain
  2. vomitting
  3. abdominal distension
  4. constipation/obstipation
  5. Fever
  6. Urine output
  7. GIT bleed or underlying disorder
  8. Past Surgical History: Previous surgery
  9. Past Medical History: Previous stroke, HIV
  10. Risk of Malignancy: Age, Loss of weight/appetite, Previous cancer, Family history of cancer
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19
Q

Describe the presentation of abdominal pain?

A

Visceral pain secondary to distention: colicky, 4-5 days duration
Centered on the umbilicus (small bowel) or lower abdomen (large bowel)
Complete obstruction: constant, sharp pain
Strangulation: pain is severe and constant
Volvulus: sudden, severe pain –
Paralytic ileus: no pain involved

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20
Q

Describe the presentation of vomiting?

A

Ask if projectile, bilious or fecal stained
Time and load of vomitus can determine if obstruction is proximal or distal
High SB: greenish blue, bile stained
Lower SB: brown and increasingly foul smelling (feculent = thick brown foul)
LB: uncommon esp. if competent ileocecal valve, usually late symptom

21
Q

Describe the presentation of abdominal distention?

A

Prominent feature in large intestinal (distal) obstruction
Usually not seen in high obstruction, esp. if patient is vomiting
Closed loop: RIF bulge that is hyper-resonant
SB: distension in centre of abdomen

22
Q

Describe the presentation of constipation/obstipation?

A
  1. Constipation (where flatus only is passed)
  2. Obstipation (where neither faeces nor flatus is passed) – cardinal feature of complete intestinal obstruction
    - Ask patient about NORMAL BOWEL OUTPUT FREQUENCY
23
Q

How can you tell the difference between SBO vs LBO in terms of presentation?

A

Vomiting first = high obstruction. Distention first = Low obstruction

24
Q

General appearance under physical examination?

A
  1. Cachexia
  2. Abdominal distension
  3. Confusion
  4. Dehydration
25
Q

Vital signs under physical examination?

A
  1. Fever
  2. Hypotension
  3. Tachycardia (Sepsis)
26
Q

Peripherals under physical examination?

A
  1. Signs of dehydration
  2. Signs of shock
  3. Palpate lymph nodes
27
Q

Signs of dehydration?

A
  1. dry mucus membranes
  2. reduced skin turgor
  3. depressed fontanelles
  4. low urine ouput
28
Q

Signs of shock?

A
  1. capillary refill time <3s
  2. weak and fast pulses
29
Q

Physical examination of the abdomen?

A
  1. Distension
  2. Scars
  3. Visible peristalsis
  4. Tenderness
  5. Signs of peritonitis
  6. Masses
  7. Hernia
  8. Tympanic or dull percussion
  9. Bowel sounds (tinkling, hyperactive, absent or sluggish
30
Q

Signs of peritonitis?

A
  1. guarding
  2. rebound tenderness
31
Q

Digital rectal exam under physical examination?

A
  1. Masses
  2. Stools (soft, hard, empty, blood)
32
Q

Differential diagnosis of small bowel obstruction?

A

Adhesions
Hernias
Volvulus
Crohn’s disease causing adhesions or inflammatory strictures
Neoplasms: benign or malignant
Ischemic strictures/mesenteric ischaemia
Foreign bodies (gallstone ileus, swallowed objects)

33
Q

Differential diagnosis of small bowel obsrtuction in children?

A
  1. Intussusception
  2. Intestinal atresia
34
Q

Differential diagnosis of large bowel obstruction?

A

Colon cancer
Volvulus
Hernia
Strictures – diverticulitis, inflammatory bowel disease

35
Q

Differential diagnosis of large bowel obstruction in children?

A

Atresia
Anorectal malformations
Hirschprungs disease

36
Q

Differential diagnosis of abdominal distension?

A
  1. Flatus
  2. fecal
  3. Fluid
  4. Fetus
37
Q

Herniation of bowels?

A
38
Q

Adhesions of the bowels?

A
39
Q

Volvulus of the bowels?

A
40
Q

Intussuception of the bowels?

A
41
Q

X-ray findings in small bowel obstruction?

A

Centrally located loop
Plicae circulares/ Valvular coniventes
Lack of distal air
Size?

42
Q

X-ray findings in large bowel obstruction?

A

Peripherally located loop
Haustra
Lack of distal air??
Size?

43
Q

What are fluid levels?

A

In general ≥ 5 fluid levels are diagnostic of intestinal obstruction
In the small bowel – number of air fluid levels is directly proportional to the degree of obstruction and to its site (more number = distal lesion)

44
Q

What is the coffee bean sign?

A
45
Q

What is the thumb print sign?

A

Mucosal thickening - ‘thumb-printing

46
Q

What is Riglers sign?

A

double wall sign (obvious bowel wall due to extra-luminal air)

47
Q

Principles of management?

A
  1. GI drainage
  2. Fluid and electrolyte replacement
  3. Relief of obstruction
48
Q

Initial managemnt?

A

ABCDE
IV access
IV fluid resuscitation
Full Blood Count
Grouping and Save
Urea, creatinine and electrolytes
Nasogastric tube
Keep NPO
Urinary catheter: Monitor urine output
Antibiotics
Abdominal X-ray (Erect and supine) and Chest X-ray
CT- Abdomen and Chest

49
Q

Arterial blood gases?

A

ABCs: SO2 and Breathing
FBC: sepsis, anemia, PLT
NPO: bowel rest and decompression
NGT: continuous suction vs passive
IVF: K+ and Cl- depletion. Correct electrolyte imbalance
Antibiotics: broad spectrulum in ischeamic bowel and perforation. IV ceft and Metro

50
Q

Definitive management?

A

Depends on the cause of the obstruction
1. Post op paralytic ileus: Supportive management
2. Sigmoid volvulus and Adhesions: Non-surgical vs Surgical management
3. Closed loop obstruction, Ischeamic bowel and perforation: Laparatomy
4. Obstructed hernia: Hernia repair

MBBS 3: Surgery (42 decks)

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