Intestinal Obstruction

Question 1

What are the sx of bowel obstruction?

Answer 1

Vomiting
-undigested food in gastric outlet obstruction
-bilious vomiting in upper SBO
-faeculent vomiting in distal SBO
Pain
-colicky abdo pain in early obstruction
-pain absent in long-standing obstruction
Constipation (not absolute in proximal obstruction)

Question 2

What are the signs of bowel obstruction?

Answer 2

Distention
Tinkling bowel sounds
Dehydration
Central resonance to percussion w/ dull flanks
Scars (prev surgery causing adhesions)
Palpable mass (causing obstruction)
NO ABDO TENDERNESS (unless strangulation)

Question 3

What are the common causes of small bowel obstruction?

Answer 3

Adhesions (80%)
Herniae
Chron’s disease
Intussusception

Question 4

What are the common causes of large bowel obstruction?

Answer 4

Carcinoma of the colon
Diverticular disease
Sigmoid volvulus
Constipation

Question 5

What are the complications of bowel obstruction?

Answer 5

Strangulation (ischaemia & necrosis)
Bacterial proliferation
Bowel perforation

Question 6

What are the appropriate investigations in suspected bowel obstruction?

Answer 6

Bloods - FBC, U&Es, amylase, LFTs, ABG
Urinalysis
Supine AXR (distended proximal bowel, absent gas distally)
Erect CXR (fluid levels in SBO, air under diaphragm)
Contrast enema (obstruction vs pseudo-obstruction)
CT

Question 7

What is a paralytic ileus?

Answer 7

Temporary disruption of normal peristaltic activity w/o mechanical blockage

Question 8

What are the causes of a paralytic ileus?

Answer 8

Post-surgery (normal <4/7)
Due to anastamotic leak/intra-abdominal sepsis
Electrolyte disturbances
Critically unwell pts on ITU w/ multiple injuries

Question 9

What is the management of a paralytic ileus?

Answer 9

NBM w/ NG feeding

Question 10

What is the main potential complication of a post-op paralytic ileus?

Answer 10

May develop into mechanical ileus caused by adhesions

Question 11

How can a paralytic and mechanical ileus be distinguished?

Answer 11

Bowel sounds 
   -absent in paralytic 
   -present in SBO
AXR
   -one air-fluid level in paralytic
   -variable air-fluid levels in SBO

Question 12

What is pseudo-obstruction?

Answer 12

Large bowel obstruction when no identifiable cause can be found

Question 13

What are the clinical features of strangulation?

Answer 13

Increasing pain/tenderness
Peritonism
Absent bowel sounds
Leukocytosis
Systemic upset

Question 14

What is a volvulus?

Answer 14

Twisting loop of bowel around mesenteric axis, resulting in obstruction and venous occlusion at base of mesentery

Question 15

What are the two common types of volvulus?

Answer 15

Sigmoid

Caecal

Question 16

What are the features of a sigmoid volvulus?

Answer 16

Most common in elderly, constipated pts
‘Coffee bean’ appearance on AXR
Treated by insertion of long flatus tube into sigmoid
-can require emergency laparotomy

Question 17

What are the features of a caecal volvulus?

Answer 17

Due to congenital malrotation
‘embryo’ appearance of ectopically placed caecum on AXR
Treated by untwisting at laparotomy

Question 18

How can small and large bowel obstruction be distinguished?

Answer 18

Vomiting
   -absent/faeculant in LBO
   -bilious in SBO
Constipatin
   -absolute in LBO
   -may not be absolute in SBO
Progression
   -more rapid in SBO

Question 19

How should small bowel obstruction be managed?

Answer 19

A-E resus
NBM + NG decompression of stomach (Ryle’s tube)
Surgical management & a/b if signs of strangulation

Question 20

How should large bowel obstruction be managed?

Answer 20

Operative management (Hartmann's procedure)
If due to faecal impaction enemas/manual evacuation

Question 21

What are the most common causes of intestinal obstruction in children?

Answer 21

Intussusception
Incarcerated hernias
Malrotation of bowel w/ midgut volvulus
Hirschsprung's disease
Meconium ileus (CF pts)

Question 22

What are the features of intussusception in children?

Answer 22

3mo-6yrs
Intermittent colic
Redcurrent jelly PR bleeding (late sign)
Sausage shaped mass in upper abdo
TREAT W/ AIR INSUFFLATION

Question 23

What are the features of malrotation in children?

Answer 23

Obstruction
PR blood/mucous
Abnormal bowel positioning on AXR w/ contrast

Question 24

What are the features of Hirschsprung’s in children?

Answer 24

Failure to pass meconium

Bilious vomiting

Question 25

What are the risk factors for faecal impaction?

Answer 25

Poor diet, dehydration
Lack of exercise, old age, pain
IBS
Fissure, stricture, rectal prolapse
Hypercalcaemia, hypothyroid, hypokalaemia
Opiates, anticholinergics, Fe, Al based antacids, diuretics
Spinal/pelvic nerve injury, diabetic neuropathy, Hirschsprung’s