Intestinal Obstruction

Question 1

What are the three ways to classify bowel obstruction?

Answer 1

Simple
Closed Loop
Strangulated (compromised blood supply)

Question 2

What are the two most common ways for a closed loop bowel obstruction to occur?

Answer 2

Volvulus

Left colorectal cancer with competent ileocaecal valve (faeces can’t pass back through the valve)

Question 3

What clinical signs will you see for a strangulated bowel obstruction?

Answer 3

Localised constant pain + peritonism
Fever
Raised WCC

Question 4

What are the two most common causes of small bowel obstruction?

Answer 4

Adhesions (60%)

Hernia

Question 5

What are the three most common causes of large bowel obstruction?

Answer 5

Colorectal neoplasia (60%)
Diverticular stricture (20%)
Volvulus (5%)

Question 6

How would you classify the causes of bowel obstruction into three areas?

Answer 6

Intra-luminal
Mural
Extra-mural

Question 7

What is the main adynamic/non-mechanical cause of bowel obstruction?

Answer 7

Paralytic ileus

Question 8

Does paralytic ileus normally cause obstruction in the small or large bowel?

Answer 8

Small

Question 9

Name the 7 causes of paralytic ileus

Answer 9

Post-op
Peritonitis
Pancreatitis or any localised inflammation
Poisons/Drugs: Anti-AChM (e.g. TCA’s)
Pseudo-obstruction
Metabolic: hypokal, hyponat, hypomag, uraemia
Mesenteric ischaemia

Question 10

Name some intraluminal causes of bowel obstruction (3)

Answer 10

Impacted matter: faeces, worms, bezoars
Intussusception
Gallstones

Question 11

Name some mural causes of bowel obstruction (3)

Answer 11

Benign stricture (IBD, surgery, ischaemic colitis, diverticulitis, radiotherapy)
Neoplasia
Congenital Atresia

Question 12

Name some extra-mural causes of bowel obstruction (4)

Answer 12

Hernia
Adhesions
Volvulus
Extrinsic compression (pseudocyst, abscess, haematoma, ovarian tumour, congenital bands - eg Ladd’s)

Question 13

In a bowel obstruction Hx, what does constant/localised pain suggest?

Answer 13

Strangulation or impending perforation

Question 14

What are the three main symptoms of bowel obstruction

Answer 14

Abdo pain
Distension
Vomiting

Question 15

What are the 8 main considerations on abdo exam for someone with ?bowel obstruction

Answer 15

Raised HR (strangulation)
Dehydration
Fever
Surgical scars
Hernias
Mass (neoplastic or inflammatory)
Bowel sounds
PR

Question 16

What 5 blood tests would you order for someone with ?bowel obstruction

Answer 16

FBC (WCC)
U+E (dehydration, electrolyte abnormalities)
Amylase (goes up if strangulation/perforation)
VBG (increased lactate in strangulation)
G+S, clotting (may need surgery)

Question 17

What imaging would you order for ?bowel obstruction

Answer 17

Erect CXR
AXR
CT to show blockage area
Gastrograffin studies

Question 18

What procedure can be used to therapeutically stent a bowel obstruction?

Answer 18

Colonoscopy

Question 19

How do you tell the difference between small and large bowel obstruction on AXR?

Answer 19

SB - Valvulae coniventes (completely across)

LB - Haustra (partially across)

Question 20

What are the four things to do that make up a ‘drip and suck’

Answer 20

NBM
IVI
NGT
Catheter

Question 21

Medical Mx for bowel obstruction?

Answer 21

Analgesia

Abx if strangulated/perf - Cef + met

Question 22

Why is the sigmoid colon more prone to volvulus?

Answer 22

Long mesentery and narrow base

Question 23

Having what diseases increases your risk of getting sigmoid volvulus?

Answer 23

Neuropsych - disease+treatments interfere with intestinal motility

MS
PD
Psychiatric

Question 24

What characteristic sign on AXR suggests sigmoid volvulus?

Answer 24

Coffee bean sign

Question 25

Mx of sigmoid volvulus

Answer 25

Sigmoidoscopy + flatus tube

Sigmoid colectomy may be required

Often recurs - elective sigmoidectomy may be required