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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is mechanical bowel obstruction?

A

something physical blocking bowel lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is bowel obstruction diagnosed?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What portion of all bowel obstructions does SBO make up?

A

around 80%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the cardinal features of SBO?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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
What are the cardinal signs of LBO?
distension absolute constipation pain vominting later
26
What are the most common causes of LBO?
``` neoplasm - 90% malignancy structure - diverticular/ischaemic/inflammatory - 3% volvulus - 5% intussusception impaction or obstipation ```
27
How is LBO managed?
first-line = supportive treatment | if perforation is suspected or impending --> emergency surgery
28
Which surgical procedure would you use to treat ___? a. caecal volvulus/colorectal malignancy/diverticular disease b. endometriosis c. pelvic abscess d. foreign body
a. laparotomy b. resection c. percutaneous or transrectal drainage --> resection d. transluminal removal or laparotomy
29
What are the potential post-LBO operation complications?
``` bleeding incisional hernia damage to nearby organs scar tissue wound dehiscence aka wound tearing skin irritation ```
30
How can you classify LBO?
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
How can XR be used to diagnose LBO?
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