Abdominal pain

Abdominal X-ray Interpretation

• ABDO-X
  • Air
  • Bowel
  • Dense structures and calcifications
  • Organs
  • Xtra tubes
• 3-6-9 rule
  • Small bowel 3cm wide
  • Large bowel 6cm wide
  • Caecum 9cm wide
• Small bowel vs. Large bowel
  • Ascending and descending colon are retroperitoneal and fixed in position
  • Small bowel usually in the middle of the abdomen
  • Small bowel has valvulae conniventes traversing the entire bowel
  • Large bowel have haustra that do not traverse the entire bowel
• Riglers sign = Clear bowel wall with air either side = Free intraperitoneal gas

• Radiographic ascites = Central displacement of bowel
• Bowel wall thickening appears as thumbprinting

Bowel inflammation

CT interpretation

• Duodenum lies between aorta and superior mesenteric artery
• Fat either side of the ileocaecal junction helps to define where this is
• The ileocaecal junction, DJ flexure, ascending colon, descending colon and rectum are all fixed points you can use to orient yourself first
• Typhlitis – Typically affect the ascending colon and caecum
• Pseudomembraneous colitis
  • Pancolitis with ‘accordion sign’
  • Described as wet colitis as has a tendency to be associated with ascites

Ischaemic colitis

• Watershed from low-flow or non-occlusive atheromatous disease
• Splenic flexure typically
• Fairly good prognosis as compared to mesenteric ischaemia

Bowel ischaemia

Must have a low threshold for investigating small bowel ischaemia, need to recognise the signs of this, diagnose the cause and identify complications (infarction +- perforation).

*Target sign is enhancement of the mucosa and serosa of the bowel with intervening low uptake

Paralytic ileus

Distended small bowel +- large bowel with no transition point

DDx

• Post-operative
• Peritonitis
• Potassium
• Pelvic and spinal #
• Pregnancy

Collections vs. Free fluid

Collections have thick enhancing margins, gas admixed in them, do not communicate with any bowel loop and will often lie near a site of anastamosis or resection.

Normal to have free gas for 3 days post-laparoscopy and 5 days post-laparotomy.

Last Updated on March 27, 2024 by Andrew Crofton