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Met 3A > Bowel Obstruction > Flashcards

Bowel Obstruction Flashcards

1
Q

How much fluid is excreted by ____ in a day? What is its pH?

a. saliva
b. stomach
c. brunner’s glands
d. pancreas
e. bile
f. SI
g. LI

A

a. 1000ml pH 6.0-7.0
b. 1500ml pH 1.0-3.0
c. 200ml pH 8.0-9.0
d. 1000-1500ml pH 8.0-8.3
e. 1000ml pH 7.8
f. 1800ml pH 7.5-8.0
g. 200ml pH 7.5-8.0

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2
Q

How is fluid lost in bowel obstruction?

A

obstruction –> distention –> nervous impulses –> emesis –> fluid loss

occlusion –> gross distension of proximal bowel –> increased peristalsis secretions of electrolyte-rich fluids into the bowel lumen

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3
Q

What is mechanical bowel obstruction?

A

something physical blocking bowel lumen

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4
Q

What is adynamic bowel obstruction?

A

eg adynamic ileus
= failure of passage of enteric contents through small bowel and colon that are not mechanically obstructed
= paralysis of intestinal motility

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5
Q

What can cause adynamic ileus?

A 
drugs eg opioids
metabolic eg hyponatraemia
sepsis
trauma or surgery
MI/CHF
head injury
peritonitis
retroperitoneal haematoma
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6
Q

How is bowel obstruction diagnosed?

A

generalised uniform gaseous distension of large/small bowel on radiograph
may have a localised sentinal loop

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7
Q

What is the difference between simple and complex obstruction?

A

Simple = no evidence of risk of perforation

Complex = bowel looks ischaemic or perforated - may occur in closed loops or necrotic bowel

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8
Q

What is a closed-loop obstruction?

A

two points along the course of bowel are obstructed
usually due to adhesions
in large bowel = volvulus

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9
Q

What is pseudo-obstruction?

A

= clinical features of SBO w/o any mechanical cause
often painless distension + constipation
consider medication, electrolytes and long-term immobility

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10
Q

What portion of all bowel obstructions does SBO make up?

A

around 80%

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11
Q

What are the cardinal features of SBO?

A

pain
distension
vomiting
absolute constipation - no faeces no flatus - after a while

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12
Q

How can you diagnose SBO on CT?

A

dilated SB loops >25-30nm from outer walls
distal normal/collapsed bowel
SB faeces sign (black dots in SB as faeces form due to excess water reabsorption)

may see;
ischaemia
perforation
mesenteric oedema (due to strangulation)
pneumatosis
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13
Q

List some common causes of SBO?

A

Extra luminal:
adhesions
hernia
volvulus

Luminal:
gallstone
intussusception
polyps

Luminal wall:
inflammatory - Crohn’s
malignancy
infarction

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14
Q

When is surgery indicated for a patient with SBO?

A

if it’s complete/complicated/strangulated

if it’s partial and conservative management hasn’t worked for the last 48-72hrs

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15
Q

What surgery is performed for SBO and how?

A 
emergency laparotomy + fluid resus
pre-operative prophylactic abx 
nasogastric decompression
analgesia
correct underlying cause

midline incision
division of adhesions and identify the transition point
milk proximal bowel through NG tube
SB resection if ischaemic - primary anastomoses with sutures/staples
examine the whole length of bowel

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16
Q

How would you treat a complex SBO if surgery is contraindicated?

A 
nasogastric decompression
IV fluid resus
analgesia
anti-emetics
antispasmodics
17
Q

How do you treat partial SBO?

A 
IV Fluid resus - Ringer's lactate/normal saline
nasogastric decompression
correct underlying cause
analgesia - morphine sulphate
Foley catheter to measure UO
anti-emetic

if poor response 48-72 hrs later –> surgery

18
Q

What biochemical changes occur as a result of SBO?

A

dehydration
vomiting
hypokalaemia + alkalosis
strangulation –> inflammatory markers

19
Q

How can XR be used to determine the extent of SBO?

A

CXR - to check for pneumoperitoneum

AXR
Partial - gas throughout abdomen + into rectum
Complete - no distal gas + staggered fluid-air levels
Complicated - free air under diaphragm + thumb-printing on bowel (ischaemia)

20
Q

What complications can arise as a result of SBO?

A 
intestinal necrosis --> perforation
sepsis
multi-organ failure
abscesses
short-bowel syndrome
21
Q

What are the complications post SBO surgery?

A

Immediate - pain, bleeding, need for stoma, anaesthesia

Early - anastomotic leak, wound breakdown, infection, DVT/PE

Late - adhesions, recurrent obstruction, scars, hernias, stoma complications

22
Q

What are the 4 main functions of the large bowel?

A

transit
storage
absorption - vitamins created by colonic bacteria eg K, thiamine and riboflavin
secretion - K+, Cl-

23
Q

What biochemical changes would you see in LBO?

A

low plasma volume
electrolyte imbalance
lactate (if ischaemic)
low HCT (if bleed)

24
Q

What clinical signs would you see in a patient with LBO?

A 
distension
quiet bowel sounds
hyper-resonant abdomen
tender + guarding
fever
peritonitis
hernias (L-sided inguinal associated with sigmoid)
25
Q

What are the cardinal signs of LBO?

A

distension
absolute constipation
pain
vominting later

26
Q

What are the most common causes of LBO?

A 
neoplasm - 90% malignancy
structure - diverticular/ischaemic/inflammatory - 3%
volvulus - 5%
intussusception
impaction or obstipation
27
Q

How is LBO managed?

A

first-line = supportive treatment

if perforation is suspected or impending –> emergency surgery

28
Q

Which surgical procedure would you use to treat ___?

a. caecal volvulus/colorectal malignancy/diverticular disease
b. endometriosis
c. pelvic abscess
d. foreign body

A

a. laparotomy
b. resection
c. percutaneous or transrectal drainage –> resection
d. transluminal removal or laparotomy

29
Q

What are the potential post-LBO operation complications?

A 
bleeding
incisional hernia
damage to nearby organs
scar tissue
wound dehiscence aka wound tearing
skin irritation
30
Q

How can you classify LBO?

A

Pathology:
dynamic - peristalsis against mechanical obstruction
adynamic - absence of peristalsis w/o obstruction

Anatomy:
SBO - high or low
LBO

Presentation:
acute
chronic
acute on chronic
subacute

Pathological changes:
simple = blood supply intact
complicated = blood supply interfered

31
Q

How can XR be used to diagnose LBO?

A

CXR - perforation

AXR - colonic dilatation
>9cm for caecum
>6cm for colon

can also visualise volvulus:
colon - coffee-bean shape
sigmoid - dilated inverted U shape
caecal - dilated R colon rotates to L side

Met 3A (19 decks)

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