Intestinal Obstruction Flashcards
1
Q
Definition of intestinal obstruction
A
Failure of downward passage of intestinal contents
2
Q
Types of intestinal obstruction
A
Dynamic
Adynamic
Simple
Stragulating
3
Q
Definition of dynamic intestinal obstruction
A
There is increasing peristalsis working against an obstructing agent
4
Q
Definition of adynamic intestinal obstruction
A
Peristalsis is absent or ineffective and there are no effective propulsive waves
5
Q
Definition of simple bowel obstruction
A
Obstruction of the intestinal lumen without interference with its blood supply
6
Q
Causes of simple bowel obstruction
A
Gallstones Impacted faeces Strictures (inflammatory or neoplastic) Adhesions Tumours (outside of wall) Obstructed hernia Pseudo obstruction
7
Q
Most common cause of a simple bowel obstruction
A
Adhesions
8
Q
What is an adhesion? Therefore what is their risk factor?
A
Fibrous bands that form between tissues and organs, often as result of an injury during surgery
RF = Previous abdominal surgery
9
Q
Pathology of a simple bowel obstruction
A
Above the obstruction - peristalsis - distension (fluid and gas) Below the obstruction - collapsed - immobile (no peristalsis) - pale At site of obstruction - perforation Third space loss Dehydration Proliferation of bacteria proximal to the obstruction Impairment of the barrier function of the intestinal mucosa
10
Q
Most common cause of a 50 y/o male with a small bowel obstruction
A
Tumour
11
Q
What is a virgin abdomen?
A
No previous abdominal surgery
12
Q
Definition of third space loss
A
Loss of ECF into a space that does not contribute to equilibrium between ICF and ECF
13
Q
Definition of transition point
A
The transition between dilated and constricted bowel
14
Q
What does a 3rd space loss result in?
A
The patient will always need more fluid than you calculate they need
15
Q
Where does the 3rd space loss happen?
A
Above the lesion
16
Q
Causes of death in simple intestinal obstruction
A
Fluid and electrolyte imbalance
Peritonitis
17
Q
What does the mucosa in the gut wall prevent?
A
Translocation of bacteria into the peritoneum by an active mechanism
18
Q
Definition of strangulating IO
A
Intestinal obstruction with persistent interference of blood supply
19
Q
Causes of strangulating IO
A
Strangulated hernia Intussusception Adhesive intestinal obstruction (late) Volvulus Vascular occlusions
20
Q
What is the window of time that you can save the bowel in strangulating IO?
A
6 - 8 hours
21
Q
Pathology of strangulation
A
Artery has the higher pressure, and so this blocks the vein first
So the blood flows in but doesn’t come out
So the bowel has a dark and blue appearance - venous ischaemia
Then results in the artery becoming blocked as well
Serosangious fluid formation - in the peritoneal cavity
Third space loss
Dehydration
Impairment of the barrier function of the intestinal mucosa
22
Q
What is in 3rd space loss in strangulation?
A
Blood
Fluid
23
Q
What does blood in the 3rd space loss may mean the patient may require?
A
Cross match
24
Q
Differences in how the patient feels in simple vs strangulation IO
A
More unwell in strangulation
25
Causes of death in strangulation IO
Peritonitis due to perforation
Hypovolaemic shock
Sepsis
26
How may perforation occur in strangulation IO?
Build up of oedema / fluid due to the venous obstruction
| This may perforate the bowel or leak out and cause obstruction
27
What is closed loop obstruction?
Occurs when some part of the gut is closed at both ends
28
In what % of people is the ileo-caecal valve competent?
75%
29
Function of ileo-caecal valve
Moves food from the small bowel to the large bowel
30
Pathology of closed loop obstruction
Bowel will dilate
This could perforate the bowel or the pressure will overcome the ileocaecal valve and will result in decompression of the small bowel
31
Where is the thinnest part of the large bowel? What is the significance of this?
Caecum
| Perforation almost always occurs here
32
What diameter of the caecum indicates perforation? What would need to be done?
10cm
| Immediate surgery
33
Presentation of intestinal obstruction
Pain
Vomiting
Abdominal distention
Absolute constipation
34
If symptoms come from up downwards (i.e. pain, vomiting etc before e.g. abdo symptoms) then what does this indicate?
Small bowel obstruction
35
If symptoms come from downwards up (i.e. abdo symptoms first, then nausea vomiting etc) then what does this indicate?
Large bowel obstruction
36
Features of the abdominal pain in intestinal obstruction
Generalised abdominal colicky pain
Each attack lasts few minutes then gradually disappears
In between attacks; periods of relief
37
What gives the pain in intestinal obstruction?
Peristalsis
38
As time goes on, what happens to the pain in intestinal obstruction?
Severity increases
| Interval between attacks decreases
39
What happens to the vomiting, the more higher up in the GI tract the obstruction is? Why is this?
More severe
Presents earlier
Due to having less time to absorb things
40
Where do most secretions occur? What does this mean for large bowel obstruction?
Proximal gut
| May not vomit at all
41
What is faecal vomiting?
Terminal ileum contents vomiting due to enteric bacterial overgrowth
NOT REAL FAECES
42
Vomiting in jejunal obstruction
Vomiting occurs with the first and each attack of pain
43
Vomiting in ileal obstruction
Vomiting delayed for a few hours
| Then it occurs with each attack of pain
44
As vomiting goes on, what is the vomitus?
First partly digested food
Then bile stained
Then "faeculent"
45
What is absaloute constipation?
No gas or stools passed
46
Presentation of high intestinal obstruction
Frequent vomiting
No distention
Intermittent pain but not classic crescendo type
47
Presentation of middle intestinal obstruction
Moderate vomiting
Moderate distention
Intermittent pain (crescendo, colicky)
With free intervals
48
Presentation of low intestinal obstruction
```
Vomiting late
Flatulent
Marked distention
Variable pain
May not be classic crescendo type
```
49
What constipation would be present in a patient with complete intestinal obstruction?
Absaloute constipation
50
What presentation of constipation would be present in a patient with partial obstruction?
Continued passage of flatus and/or stool beyond 6 - 12 hours after onset of symptoms
51
What distension would be present in jejunal obstruction?
Minimal
52
What distention would be present in ileal obstruction?
Central
53
Along with central distension in small bowel obstruction, what would also be present on the abdomen?
Collapsed flanks
54
Presentation of abdomen in colonic obstruction
General distention
55
What does flank distention indicate?
Long bowel obstruction with competent ileocaecal valve
56
What does generalised distention obstruction indicate?
Distended small bowel and colon - large bowel obstruction with incompetent ileocaecal valve
57
Causes of intestinal obstruction WITHOUT absaloute constipation
Richter's hernia
Gallstone ileus
Mesenteric vascular occlusion
Intestinal obstruction associated with pelvic abscess
58
What % of strangulated hernias are Richters hernia?
10%
59
What is a Richter's Hernia?
Herniation of the anti mesenteric wall of the bowel, usually through a small defect
60
What happens to Richters hernia more than other strangulated hernias?
Progress more rapidly to gangrene
61
Is complete obstruction frequent in Richters hernia? Why?
No, it is less frequent
| Still room to pass through
62
Signs of intestinal obstruction
Dehydration
Tachycardia
Shock (strangulation)
Scars of previous surgery (adhesive obstruction)
Visible non reducible hernia
Visible peristalsis
Step ladder appearance of abdomen due to distended loops of bowel over each other
Auscultation
- early; loud and frequent intestinal sound
- late; silent abdomen (ileus/peritonitis)
PR
- empty rectum in most cases
63
What is absent on examination in simple obstruction?
Tenderness
| Rigidity
64
What should be checked for in suspected intestinal obstruction?
Hernial orifices
65
What may a PR exam reveal?
Cause of obstruction
| e.g. rectal tumour, faecal impaction
66
Does a hernia cause pain?
NO
unless complications
However may be tender
67
Tachycardia + shock = ….
Strangulation
68
What is the most common type of hernia?
Femoral
69
What features should make you suspect internal strangulation?
Pain
- more severe
- never completely absent in between attacks
Shock
- present and progressive
Tenderness and rigidity
NG suction for 1-2 hours fails to relieve the pain
70
Why would NG suction may relieve an obstruction? In what case would this not work?
It would relieve the pressure so make the patient feel better
Not in the case of ischaemia
71
Features of an ischaemic strangulation pain
No relief periods
72
What features should make you suspect an external hernia strangulation?
Hernia swelling that is
- tense
- tender
- irreducible
- no expansible impulse on cough
73
Investigations for intestinal obstruction
```
FBC
U and Es
LFTs
ABG
AXR
Erect CXR
CT
Water soluble oral contrast
Water soluble enema
```
74
Why would Hb be done in intestinal obstruction?
Indication of bleeding / tumours
75
What does an increased WCC in intestinal obstruction indicate?
Strangulation
76
Why do U and Es have to be checked in suspected intestinal obstruction?
At risk of pre renal failure due to the fluid loss
| Hypokalaemia
77
What may be seen in AXR?
Dilated bowel loops
78
What may be seen in erect CXR? What is this an indication of?
Free air
- perforation
- late
79
Features of distended jejunal loops on AXR
Valvulae conniventes (transverse, complete, regular striations) giving concertina effect
80
Features of distended ileal loops on AXR
Characterless / featureless tube
81
Features of distended colon on AXR
Haustrations
82
Sensitivity of AXR
60 - 90%
83
What is the diameter of a dilated small bowel?
> 2.5 - 3cm in diameter
84
What does a normal AXR NOT exclude the diagnosis of?
Short bowel syndrome
85
If there is a tumour in the left side of the colon, what would this present with?
Fresh blood PR
86
If there is a tumour on the right side of the colon, what would this present with?
Anaemia
87
What lab results would be indicative of liver metastases?
Increased LFTs
| Decreased Hb
88
What would a high / proximal small bowel obstruction look like on AXR?
Minimal small bowel loops
89
What would a low / distal small bowel obstruction look like on AXR?
Dilated small bowel loops
90
What would a large bowel obstruction look like on AXR?
Dilated large bowel loops
91
What is looked for in suspected intestinal obstruction on CT?
Confirm the diagnosis if transition point is seen
Identify the level (SBO/LBO)
Find the cause
Detection of ischaemia
Detection of bowel perforation
Staging in obstruction secondary to malignancy
92
What does CT have a limited sensitivity in?
Partial bowel obstruction
93
How does water soluble oral contrast work?
100ml of gastrogaffin orally or through NG tube
Serial AXRs performed to monitor the passage of the contrast medium through the small bowel
Appearance of the contrast in the caecum within 6 hours is predictive of non surgical resolution of adhesive small bowel obstruction
94
What may the contrast of water soluble oral contrast have?
Therapeutic effect
95
What can a water soluble enema be used to confirm the diagnosis of?
Large bowel obstruction
96
Common causes of IO in the newborn
Imperforate anus
Congenital atresia
Stenosis of the gut
Volvulus
97
Cause of 2 - 3 month old with IO
Strangulated hernia
98
Cause of a 3 - 12 month old with IO
Intussception
99
Cause of young adults with IO
Strangulated hernia
| Post op adhesions
100
Causes of IO in old age
Strangulated hernias
Post op adhesions
Colon cancer
Colonic volvulus
101
Treatment of intestinal obstruction
NG tube
Resus with restoration of fluid and electrolyte balance
Surgery - laparotomy / laparoscopy
102
Why would an NG tube be used in treatment of IO?
To prevent the risk of aspiration, especially in SBO due to vomiting
103
Indications for early surgery in IO
Obstructed hernia
Suspected strangulation
Small bowel obstruction in a 'virgin abdomen'
Failure of conservative treatment in adhesive SBO
Obstructing tumours on CT
104
Where is the tumour found when there is small bowel obstruction from the tumour?
Ileocaecal valve
105
Definition of intussusception
Invagination of an intestinal segment into an adjacent loop
106
Causes of intussusception
Polyp
Submucous lipoma
Polypoidal tumours
Inverted Meckel's diverticulum
107
What does protrusion invite?
Intussusception
108
Treatment of intussusception
Laparotomy resection
| +/- anastomoses
109
What is avoided in treatment of intussusception in children?
Surgery
110
Presentation of paediatric intussusception
Recurrent episodes of screaming and drawing up legs
Vomiting
Redcurrent jelly stools
Sausage shaped mass on examination
111
Investigations of paediatric intussusception
Abdominal USS
| GG enema currently rarely used
112
Treatment of paediatric intussusception
Reduction by air enema
113
When is surgery used in paediatric intussusception?
Failed reduction
| Suspected strangulation
114
Definition of volvulus
Axial rotation of the gut
115
Types of volvulus
Volvulus neonatorum
Volvulus of small intestine in adults
Volvulus of the caecum
Sigmoid volvulus
116
Pathology of volvulus of small intestine in adults
Post op adhesions between the antimesenteric border of the intestine and the anterior abdominal wall
117
What type of volvulus is most common?
Sigmoid volvulus
118
When does caecal volvulus occur?
If the right colon has a long and mobile mesentery
| It occurs in a clockwise direction
119
Diagnosis of caecal volvulus
AXR
| CT
120
Treatment of caecal volvulus
Right hemicolectomy
| +/- ileo-colic anastomosis
121
Who is sigmoid volvulus common in?
Elderly males
122
Presentation of sigmoid volvulus
Sudden left sided abdominal pain
Abdominal distension
Absaloute constipation
Vomiting rare
123
What is seen on plain X ray in sigmoid volvulus?
Dilated colon - "coffee bean" sign
124
Treatment of sigmoid volvulus
Emergency endoscopic decompression
| Subsequent sigmoid resection in fit patients
125
What gender gets caecal volvulus more?
Females
126
Causes of adhesive intestinal obstructive
Post operative adhesions
127
Treatment for adhesive IO
NG tube
IVI
Pain relief
Indications for surgery
128
Why is surgery not done routinely for adhesive IO?
As the operations in the first place caused the obstruction
129
Indications for surgery in adhesive IO
Suspected strangulation
| Failure of conservative treatment after 48 HOURS
130
Pathology of gallstone ileus
Gallstone impaction at terminal ileum
Erodes all of the walls
Creates a fistula between the duodenum and gallbladder
131
Presentation of gall stone ileus
Small bowel obstruction
132
Investigations for gallstone ileus
AXR
| CT
133
What would be seen on AXR in gallstone ileus?
Small bowel obstruction
Air in the biliary tree
Stone may be seen
134
Treatment of gallstone ileus
Laparotomy
- enterotomy and removal of the gallstone (enterolithotomy)
+/- cholecystectomy
135
Definition of cholecystectomy
Removal of gallbladder
136
What is mesenteric vascular occlusion?
Occlusion of the superior (rarely the inferior) mesenteric vessels or one of its branches
137
Causes of mesenteric vascular occlusion
```
Arterial embolism
- AF
- SBE
Arterial thrombosis
- polycythaemia
- atherosclerosis
- contraceptive pills
Venous thrombosis
- Portal HTN
```
138
Who is mesenteric vascular occlusion common in?
Elderly
139
Presentation of mesenteric vascular occlusion
```
Pain
- sudden
- severe
- out of proportion to the physical signs
Occasionally passage of blood and mucous per rectum
Shock
Abdominal tenderness and rigidity
- mild initially but marked later on
```
140
Investigations of mesenteric vascular occlusion
ABG
| CT angiogram
141
Prognosis of mesenteric vascular occlusion compared to any other type of intestinal obstruction
Higher mortality
142
Treatment of mesenteric vascular occlusion
```
Pre op
- GI suction
- IV fluids
- antibiotics
Operative
- laparotomy
```
143
Definition of paralytic ileus
Cessation of peristalsis due to failure of neuromuscular mechanism of the intestine
144
Pathology of paralytic ileus
Cessation of peristalsis
| Accumulation of fluid and gas in intestine
145
Presentation of paralytic ileus
```
History of an underlying disorder
Distention - progressive
Vomiting or increased NG tube output
Failure to pass flatus - absolute constipation
Absent intestinal sounds
NO PAIN (no peristalsis)
False shifting dullness
```
146
Causes of paralytic ileus
```
Major abdominal surgery
Peritonitis
Following fracture of spine
Retroperitoneal haemorrhage
Uraemia
Hypokalaemia
```
147
What is absent on CT in paralytic ileus?
Transition point
148
Why in paralytic ileus is there false shifting dullness?
Fluid accumulated in dilated intestinal loops
149
On auscultation of paralytic ileus, there is a dead silent abdomen. However sometimes high pitched intestinal sounds may be heard. Why is this?
Passage of fluid from one distended loop to another
150
Investigations of paralytic ileus
AXR - dilated small bowel loops
| CT - dilated small bowel loops with NO transition point
151
Treatment of paralytic ileus
NG tube
Restoration of fluid and electrolyte balance
Treatment of underlying cause as appropriate
152
Another name for large bowel pseudo-obstruction
Ogilvie syndrome
153
Definition of large bowel pseudo-obstruction
Clinical syndrome with symptoms, signs and AXR of LBO but with no identifiable mechanical obstruction
154
Who gets large bowel pseudo-obstruction?
Elderly patients
| +/- recent surgery
155
Causes / associations of large bowel pseudo obstruction
```
Severe pulmonary of CV disease
Severe electrolyte disturbance
- hyponatraemia
- hypokalaemia
- hypomagnesaemia
- hypo/hypercalcaemia
Malignancy
Systemic infection
Medications
- opoids
- anticholingergic
- clonidine
- amphetamimnes
- phenothiazines
- steriods
```
156
What is metabolic acidosis an important feature of? And therefore what test should you do if you suspect it?
Ischaemic bowel
| ABG
157
First line investigation for acute mesenteric ischaemic
Lactate
158
What is the most likely area to be hit with ischaemic colitis?
Splenic flexure
159
Investigation of bowel ischaemia
CT
160
Types of bowel ischaemia
Acute mesenteric ischaemia
Chronic mesenteric ischaemia
Ischaemic colitis
161
Pathology of acute mesenteric ischaemia
Embolism resulting in occlusion of an artery which supplies the small bowel for example the superior mesenteric artery
162
What do patients who get acute mesenteric ischaemia classically have a history of?
AF
163
Another name for chronic mesenteric ischaemia
Ischaemic angina
164
Presentation of chronic mesenteric ischaemia
Colicky, intermittent abdominal pain occur
| Non specific features
165
Pathology of ischaemic colitis
Acute but transient compromise in the blood flow to the large bowel
May lead to inflammation, ulceration and haemorrhage
166
Where is ischaemic colitis most likely to affect?
Watershed areas such as the splenic flexure that are located at the borders of the territory supplied by the superior and inferior mesenteric arteries
167
Investigations of ischaemic colitis and what is seen?
AXR - thumbprinting due to mucosal oedema/ haemorrhage
168
Management of ischaemic colitis
Usually supportive
Surgery in minority of cases if
- conservative measures fail
- generalised peritonitis / perforation / ongoing haemorrhage
