Intestinal obstruction

Question 1

what form of obstruction is the most acute? why?

Answer 1

small bowel
proximal obstruction –> large volume of gastric and pancreatoduodenal secretion can not progress –> reflux into the stomach –> vomited up

Question 2

what can cause intestinal obstruction?

Answer 2

extraluminal :

• adhesions: previous surgery / intra-peritoneal infection
• tumors: compression
• congenital bands
• hernia: strangulated femoral/inguinal

mural:

• tumours
• inflammatory strictures: Crohn’s, Diverticular disease
• drug-induced strictures e.g. NSAIDs
• lymphomas
• intussusception (esp children)- segment of bowel gets telescoping into distal bowel, usually initiated by a mass

Intraluminal

• impacted faeces - common
• solitary gallstone
• phytobezoar: mass of impacted veg matter e.g pith
• Trichobezoar: found in disturbed people who eat their own hair over a long period

Question 3

what are the symptoms of obstruction??

Answer 3

• Colicky Pain
  not the most prominent factor - area gives an idea of where the obstruction is.
• Vomiting
  the more proximal the obstruction the sooner this develops
  the contents also indicate area (e.g. bilious = small, large = faeculent)
• Absolute Constipation
  no faces or flatus
• abdominal distention

Question 4

what is a closed-loop obstruction?
when does it develop?
whats its significance?

Answer 4

this occurs when there is another obstruction more proximal.

it develops in volvulus or in large bowel obstruction where the ileocaecal valve remain competent

increased peristalsis of bowel –> secretion of large volumes of fluid –> bowel distends as fluid remains between the two points of obstruction –> bowel wall stretches –> ischaemia +/- perforations

Question 5

how does incomplete obstruction present?

Answer 5

clinical features are less distinct

however chronic –> hypertrophy of bowel wall –> strong peristaltic activity –> colicky pain + visible peristalsis

Question 6

what are the physical signs of intestinal obstruction?

Answer 6

• Abdo distension (the more distal the obstruction the more distended)
• groin examination: may show a lump if incarcerated hernia

Abdo examination:

• scars from previous surgeries (adhesions)
• no tenderness
• resonant on percussion
• high pitched tinkling on auscultation
• succussion splash - heard on shaking abdo from one side to another - gastric outlet obstruction*

Question 7

what investigations are performed in suspected bowel obstruction?
what are the relevant findings?

Answer 7

labs
routine urgent bloods:
FBC,CRP,U&E,LFT and group+save
venous blood gas - high lactate for ischaemia

imaging 
AXR- 
small bowel obstruction:
- dilated > 3cm 
- central abdo location
- pilcae circulares 

large

• dilated bowel >6cm / > 9cm at caecum
• peripheral location
• haustra

an incompetent ileocaecal valve could show both areas being distended

CT scan with IV contrast:

Question 8

why is CT abdo a better imaging technique for bowel obstruction than AXR

Answer 8

• more sensitive for obstruction
• can differentiate between mechanical and pseudo-obstruction
• can demonstrate site and cause
• shows metastasis if malignancy is the underlying cause

Question 9

how is bowel obstruction managed?

Answer 9

• resuscitation : NBM, IV fluids
• NG tube to aspirate small bowel content - helps with vomiting and reduces distension
• urine catheter - fluid balance
• if the cause is adhesions –> resolve with conservative management for 4 days
• faecal impaction: enemas or manual removal of faeces
• bowel stenting: in those with left-sided colon obstruction due to ca. cancer resected after patient scondition improves
• operation:
  can be deferred if not strangulated/ obstructed hernia/ caecal distension.
  typically a laparotomy

Question 10

what are the complications of bowel obstruction?

Answer 10

bowel ischaemia
bowel perforation - faecal peritonitis
dehydration and renal impairment