bowel obstruction

Question 1

Differential diagnoses for a man who hasn’t opened bowels for 6 days and who has been vomiting

Answer 1

Bowel obstruction
Constipation
Paralytic ileus
Toxic megacolon

Question 2

What is paralytic ileus

Answer 2

functional obstruction of bowel due to temporary paralysis which usually affects the whole bowel
-COmmon post op

Question 3

What is toxic megacolon

Answer 3

Acute colonic distension
Due to acute colitis and system toxicity
Secondary to IBD or colonic infections such as C.Diff

Question 4

What is bowel obstruction

Answer 4

Mechanical (physical) or functional (decreased bowel motility) blockage of the bowel, resulting in absolute constipation. There will be dilatation of proximal bowel with accumulation of fluid into the intestinal lumen

Question 5

4 key symptoms of bowel obstruction

Answer 5

Nausea and vomiting
Colicky abdominal pain
Abdominal distension
Absolute constipation

Question 6

How do the symptoms of small bowel obstruction present

Answer 6

Vomiting is early feature. Constipation is often late

Question 7

How do symptoms of large bowel obstruction present

Answer 7

Vomiting is a late feature
Constipation and pain is early
Pain in supra-pubis

Question 8

Signs of bowel obstruction (when examined)

Answer 8

Abdominal distension
Abdo tenderness (sharp and constant is a sign of ischaemia)
Central resonance to percussion
Tinkling bowel sounds when auscultating
Dehydration (vomiting and lack of fluid intake and third spacing)

Question 9

What is ‘third spacing’ and why does ti cause dehydration

Answer 9

Bowel occlusion leads to gross dilatation of proximal limb. This leads to increased bowel peristalsis and increased secretions of electrolyte rich fluid into the bowel

-Can lead to hypokalaemia,

Question 10

consequences of a strangulating obstruction

Answer 10

Blood supply compromised which leads to infarction and therefore perforation. BOwel contents released and can lead to peritonitis.

Question 11

what are strangulating obstructions

Answer 11

Interruption of intestinal blood supply with simultaneous blockage of intestinal lumen

Question 12

Signs of peritonitis

Answer 12

Colicky pain --> continuous
Tachycardia
Oyrexia
Peritonism
Decreased or absent bowel sounds 
Raised CRP AND WCC

Question 13

What is a closed loop obstruction

Answer 13

Obstruction with two obstructed points.

\Bowel will become distended, stretching the bowel wall until it becomes ischaemic and perforates

Question 14

What is the ileocaecal valve

Answer 14

Between small bowel and large bowel which stops the contents of large bowel back flowing

Question 15

Complications concerning the ileocaecal valve

Answer 15

If large bowel becomes blocked and ileocaecal valve closes (competent), causes a closed loop obstruction

Question 16

What is sigmoid volvulus

Answer 16

When bowel twists around itself which leads to a closed loop obstruction

Question 17

mechanical bowel obstruction common causes

Answer 17

Adhesions
Hernias
Crohn's
Malignancy
Diverticular disease
Volvulus

Question 18

Exams and investigations for a suspected bowel obstruction

Answer 18

Bedside:
observations (dehydrated? shocked? infection or peritonitis)
-Abdo exam (distension, tenderness, rebound tenderness, central resonance, tinkling bowel sounds, dehydration, scars)
-Hernial orifices
-PR (obstructing mass)

Bloods:

• FBC (raised WBC= infection/inflammation due to perforation or impending perforation) Microcytic anaemia found in presence of underlying malignancy
• U&E (Hypokalaemia- colon secretes K+ and bicarbonate in exchange for na+ and h2- absorption. IF disrupted then hypokalaemia). Increased urea= severity of dehydration/renal failure
• CRP - infection/ perforation
• G&S and co-ag (pre surgery)
• VBG (metabolic derangement secondary to dehydration or excessive vomiting). High lactate- ischaemia

Basic imaging
-AXR
Erect CXR if perforation suspected
-CT

Question 19

How to differentiate between small and large bowel in X-ray

Answer 19

Small- <3cm. HAs valvular conniventes. Lies in centre of abdo

Large- <6cm. Has haustra. Lies around edge of Abdo

Question 20

What investigation should always be done in suspected bowel obstruction and why

Answer 20

CT- all obstruction is malignant until proven otherwise

Question 21

Management of small bowel obstruction

Answer 21

Drip and such

Question 22

Managemt. of large bowel obstruction

Answer 22

Surgery

Question 23

What is a sign that ischaemia may be developing

Answer 23

Rebound tenderness

Question 24

What is needed if a patient is vomiting during a small bowel obstruction

Answer 24

Patient requires a NG tube