The Gut Wall and Small/Large Bowel X-ray Flashcards
Describe the structure of the peritoneal cavity
Mesothelium lined cavity
Simple squamous epithelium on a basement membrane with dense irregular CT beneath
What is the difference between intraperitoneal and retroperitoneal viscera
Intraperitoneal viscera are lined by visceral peritoneum
Retroperitoneal viscera are not enveloped by the peritoneum and lie behind the peritoneal cavity
What is the mesentry wall and what are its functions
Fold of membrane that attaches the intestine to the abdominal wall
Allows neurovasculature to supply organs without going through the peritoneal cavity
Helps store fat
What are the layers of the gut wall and what forms each layer
Mucosa - epithelium, lamina propria and muscularis mucosae
Submucosa - layer of CT bearing glands, arteries and veins
Muscularis externae - two layers of SM; inner circular and outer longitudinal
Serosa - mesothelium and CT
What are the major functions of the GI system
Port of entry of food
Mechanical disruption of food
Temporary store of food
Chemical disruption of food
Kills pathogens in food
Moves food along tract
Absorbs nutrients from resultant solution
Eliminates residual waste material
What features can be seen on an abdominal x-ray
Bowel gas pattern
Soft tissue structures
Bones
How does a small bowel obstruction appear on AXR
Central position around umbilicus
Valvulae conniventes are visible - cross entire wall of the bowel and are thin
Describe the presentation of a small bowel obstruction and name some causes
Presentation - early vomiting, mild distension, late absolute constipation, colicky pain
Causes: hernia, adhesions, tumours, inflammation
How does a large bowel obstruction appear on an AXR
Peripheral position
Can see haustra - do not run full width
Describe the presentation of a large bowel obstruction and name some causes
Presentation - late vomiting, significant distension, pain, early absolute constipation
Causes: colorectal carcinoma, diverticular stricture, hernia, volvulus, pseudo-obstruction
What luminal diameter suggests obstruction in the small bowel, large bowel and caecum
Small bowel lumen >3cm
Large bowel lumen >6cm
Caecal lumen >9cm
What is a lead pipe colon
Featureless colon caused by loss of haustra
Have thickened wall due to chronic inflammation
Mark of fibrotic bowel
What is thumb printing on an AXR
Thumb printing show oedematous thickened haustra
Wall is thickened due to active inflammation
Mark of inflammatory changes within bowel
Name some abnormalities that can be seen on an AXR
Stones
Organs/masses
Calficiation - chronic pancreatitis, vacular (e.g. AAA), nodes
Bones
Artefact
Foreign body
Toxic megacolon
Thumb printing
Lead pipe colon
Bowel obstruction
How does perforation of the bowel appear on an x-ray and what can cause perforation of the bowel
Seen as gas under the diaphragm in an erect CXR
Causes: peptic ulcer, diverticular disease, tumour, obstruction, trauma, iatrogenic
