Presentation, Diagnosis and Management of Bowel Obstruction

Question 1

What is bowel obstruction?

Answer 1

Can occur at any part of the GI tract; there is dilatation of the bowel proximal to the obstruction, with air and fluid, and peristalsis is disrupted

Question 2

How does an upper small bowel obstruction present?

Answer 2

Acute presentation with only a couple of hours since onset; they will have vomited large volumes of gastric, pancreatic and biliary secretions, which were regurgitated into the stomach

The more proximal the obstruction, the earlier vomiting develops

Question 3

How does a distal small bowel/large bowel obstruction present?

Answer 3

Colicky abdominal pain and distension; vomiting tends to occur later and is potentially faeculent

Question 4

Symptoms of intestinal obstruction?

Answer 4

Vomiting
Pain and distension (pain receptors in abdominal wall)
Constipation

Complete or incomplete obstruction

Question 5

Why can vomiting continue to occur in bowel obstruction, even when there is nil taken by mouth?

Answer 5

GI secretions continue to be produced, e.g: saliva, gastric, pancreatic, bile, succus entericus

Question 6

Different types of vomitus, in relation to the level of obstruction?

Answer 6

Semi-digested food, eaten 1/2 days previously (with no bile) suggests gastric outlet obstruction

Copious bile-stained fluid suggests upper small bowel obstruction

Thicker, brown, foul-smelling (faeculent) suggests a more distal obstruction

Question 7

Types of pain assoc. with intestinal obstruction?

Answer 7

Distension of the bowel, caused by swallowed air and intestinal juices proximal to the obstruction, causes pain

Intermittent episodes of colicky pain, as peristalsis attempts to overcome the obstruction

Question 8

Constipation as a symptom of intestinal obstruction?

Answer 8

Propulsion of bowel contents is arrested and the bowel bowel gas is absorbed distal to the obstruction

ABSOLUTE CONSTIPATION (neither faeces nor flatus) is pathognomonic of bowel obstruction

Question 9

How do the symptoms of large bowel obstruction develop?

Answer 9

Develop more gradually in large bowel obstruction, due to the large capacity of the colon and caecum, as well as their absorptive activity

Question 10

What happens if the ileo-caecal valve remains competent in large bowel obstruction?

Answer 10

CLOSED LOOP OBSTRUCTION - backwards flow of accumulated bowel contents is PREVENTED; the thin-walled caecum progressively distends with swallowed air and may rupture

Question 11

What happens if the ileo-caecal valve becomes incompetent in large bowel obstruction?

Answer 11

Small bowel distends and the symptoms are more insidious

Question 12

Symptoms of incomplete bowel obstruction?

Answer 12

Bowel is only partially obstructed and the clinical features are more poorly defined; vomiting may be intermittent with an erratic bowel habit

Question 13

Progression of chronic incomplete obstruction?

Answer 13

Leads to gradual hypertrophy of the muscle of the bowel wall proximally; peristaltic activity in hypertrophic muscle is responsible for bouts of colicky pain, which can be more prominent than in complete obstruction

This is typical of CROHN’S DISEASE

Question 14

Physical signs of intestinal obstruction?

Answer 14

Dehydration (dry mouth, loss of skin turgor and elasticity)

Abdominal distension

Visible peristalsis

Relative LACK of abdominal tenderness (obstruction with tenderness may indicate bowel strangulation)

Obstructing abdominal mass may be palpable

On percussion, centre of abdomen tends to be RESONANT (gaseous distension)

Groins must be examined for an obstructing hernia

Bowel sounds are high-pitched and tinkling; sometimes, they are absent, echoing (cavernous-like) or may sound like lapping water

Question 15

Ix for suspected bowel obstruction?

Answer 15

Initially, a supine AXR - bowel proximal to the obstruction will be distended with gas

CT scan can be used to look for cause; a TRANSITION POINT will be seen with distended bowel (proximal) and collapsed bowel (distal) to the site of obstruction - CUT-OFF point is between the proximal and collapsed distal bowel the site of obstruction

Question 16

Distended small bowel loop appearance?

Answer 16

Tend to lie in a central position and have valvulae conniventes (these are normal on the small bowel and help to identify the structure)

Question 17

Distended large bowel appearance?

Answer 17

Tends to lie peripherally, in its anatomical appearance, and haustra coli can be seen (only used to identify the structure as large bowel)

Question 18

Principles of initial management of intestinal obstruction?

Answer 18

Nil by mouth

Insert IV cannula and obtain blood results

Resuscitate with IV fluids, replacing electrolyte losses

Pass an NG tube to decompress the stomach

Question 19

8 causes of mechanical small bowel obstruction?

Answer 19

Adhesions or bands
Volvulus

Incarcerated abdominal wall hernia
Internal hernia

Tumour (malignant large bowel obstruction with incompetent ileo-caecal valve)

Inflammatory strictures

Bolus obstruction

Intussusception

Question 20

Causes of adhesions or bands?

Answer 20

Can be congenital or may result from previous abdominal surgery/peritonitis

Question 21

Types of incarcerated abdominal wall hernias?

Answer 21

Inguinal
Femoral

Umbilical
Paraumbilical

Ventral
Incisional

Question 22

How can hernias cause bowel obstruction?

Answer 22

Structures herniating through the abdominal wall can become obstructed and potentially strangulated at the neck of the hernia

Question 23

What is a volvulus?

Answer 23

Mobile loop of bowel rotates causing obstruction at its neck; the most common type is a sigmoid volvulus and, sometimes, a caecal volvulus can occur

Question 24

Appearance of sigmoid and caecal volvuli on AXR?

Answer 24

Coffee-bean shape

Question 25

2 common causes of inflammatory strictures in bowel obstruction?

Answer 25

Crohn’s disease
Diverticular disease

These obstructions are usually incomplete

Question 26

Causes of bolus obstruction?

Answer 26

Food bolus

Impacted faeces - tends to occur in the elderly and PC CAN BE diarrhoea with a Hx of CONSTIPATION

Impacted gallstone ileus

Trichobezoar - suck long hair and form hair ball

E.g: inflammation/tumour in the distal oesophagus can trap a bolus

Question 27

What is intussusception?

Answer 27

Segment of bowel wall becomes telescoped into the segment distal to it; this is common in CHILDREN

Initiated by a mass in the bowel wall; enlargement/hypertrophy of lymphatic tissue or tumour

Question 28

What is bowel strangulation?

Answer 28

Segment of bowel becomes trapped (lumen becomes incarcerated) and the venous return becomes obstructed; with rising intravascular pressure, the arterial inflow is compromised

This progresses to gut ischaemia, infarction and perforation

Question 29

When does bowel strnagulation occur?

Answer 29

External hernias - urgent intervention if there is pain over a hernia

Volvulus

Question 30

2 causes of adynamic bowel obstruction?

Answer 30

Paralytic ileus

Pseudo-obstruction

Question 31

What is a paralytic ileus?

Answer 31

Disruption of the normal propulsive activity of the GI tract, due to failure of peristalsis.

Risk factors:
Recent GI surgery
Inflammation with peritonitis
Diabetic keto acidosis

Question 32

Risk factors for adynamic bowel obstruction?

Answer 32

Recent GI surgery
Inflammation with peritonitis
Diabetic ketoacidosis

Question 33

Symptoms and signs of a paralytic ileus?

Answer 33

Similar to bowel obstruction, although pain and high pitched bowel sounds are less common

Question 34

Treatment of paralytic ileus?

Answer 34

“Drip and suck” while awaiting restoration of peristalsis; use an NG tube to remove contents of stomach and bowel

Question 35

What is Ogilvie’s syndrome?

Answer 35

Acute dilatation of the colon in the absence of colonic obstruction in acutely unwell patients; there is pseudo-obstruction

Question 36

What is Ogilvie’s syndrome assoc. with?

Answer 36

Hip replacement surgery
CABG
Spinal #
Pneumonia
Frail/elderly patients

Question 37

Ix for Ogilvie’s syndrome?

Answer 37

AXR +/- CT scan confirms gaseous distension to distal rectum; there is no obstructing point

Question 38

Treatment of Ogilvie’s syndrome?

Answer 38

Generally, supportive treatment unless there is pain, due to distension or respiratory compromise (distension can affect diaphragm and breathing); colon may, in these cases, require colonoscopic decompression