FN: Bowel obstruction Cause and Investigations

Question 1

Classification

Answer 1

simple
Closed loop
Strangulated

Question 2

Simple

Answer 2

1 obstructing point + no vascular compromise

May be partial or complete

Question 3

Closed loop

Answer 3

Bowel obstructed @ two points

• left CRC with competent ileocaecal valve
• volvulus

Gross distension - perforation

Question 4

Strngulated

Answer 4

Compromised blood supply
Localised, constant pain + peritonism
Fever + WCC raised

Question 5

Common Causes

Answer 5

SBO: adhesions or hernias
LBO: colorectal neoplasia, diverticular disease, volvulus

Question 6

Other causes: non mechanical

Answer 6

Paralytic ileus
1. Post-op
2. peritonitis
3. Pancreatitis or any localised inflammation
4. Poisons/Drugs: anti-ACMM (e.g.s TCAs)
Pseudo-obstruction
Metabolic: reduced K, reduced Na, reduced Mg, uraemia
Mesenteric ischaemia

Question 7

Mechanical causes

Answer 7

Intraluminal:
Intramural
Extramural

Question 8

Intraluminal

Answer 8

Impacted matter: faeces, worms, bezoars
Intussusception
gallstones

Question 9

Intramural

Answer 9

Bening stricture: IBD, surgery, Ischaemic collitis, Diverticultis, radiotherapy

Neoplasia
Congenital atresia

Question 10

Extramural

Answer 10

Hernia
Adhesions
Volvulus (sigmoid, caecal, gastric)
Extrinsic Compression:
1. Pseudocyst
2. Abscess
3. Haematoma
4. Tumour e.g. ovarian
5. Congenital bands (e.g. Ladds)

Question 11

Presentation

Answer 11

Abdominal pain
distension - increased w/ lower obstructions
Vomiting
Absolute Constipation

Question 12

Abdominal pain

Answer 12

Colicky
Central but level depends on gut region
Constant/ localised pain suggests strangulation or impending perforation

Question 13

Examiantion

Answer 13

raised HR: hypovolaemia, strangulation

2. Dehydration, hypovolaemia
3. Fever: suggest inflammatory disease or strangulation
4. Surgical scares
5. Hernias
6. Mass: neoplastic or inflammatory
7. Bowel sounds
   a. mechanical obstruction
   b. Ileus
8. PR
   a. Empty rectum
   b. rectal mass
   c. hard impacted stool
   d. Blood from higher pathology

Question 14

Investigations

Answer 14

Bloods
Imaging
Gastrogaffin studies
Colonoscopy

Question 15

Bloods

Answer 15

FBC: raised WCC
U_E: dehydration, electrolyte ab.
AMylase: raised inf stragulation or perforation
VBG: raised lactate in strangulation
4. G+S clotting: may need surgery

Question 16

Imaging

Answer 16

erect CXR
AXR ! erect film for fluid levels
CT: can show transition point

Question 17

Gastrogaffin studies

Answer 17

Look for mechanical obstruction: no free flow
Follow through or enema
follow through may relieve mild mechanical obstruction usually adhesional