Abdominal X-ray and CT
DIAGNOSES
Bowel obstruction
- work out whether small or large bowel.
- work out transition point between dilated and collapsed bowel (start at rectum and work backwards).
Sigmoid volvulus
- coffee bean sign = distended segment of large bowel folded back on itself so that the twisted loops causes two compartments with a central double wall ending in the apex of the twist
Caecal volvulus
- large bowel dilation in pelvis but not coffee bean in appearance
- sigmoid and rectum normal on CT
- “whirl sign” – direct visualisation of the twisted segment of bowel
Bowel perforation in ICU
- difficult to get erect CXR
- perform a left lateral AXR -> can see free air under diaphragm and above liver
- gas on x-ray may persist for 7/7 post laparotomy
- supine AXR:
-> Rigler sign: both inner and outer borders of bowel well defined
-> football sign: air outlines the entire peritoneal cavity with a football shape
-> interloop triangular lucency: triangle of gas between two loops of bowel and abdominal wall
-> subhepatic air: RUQ outlines the inferior border of liver
-> falciform ligament outlined by air: vertical soft tissue density between umbilicus and notch between left and right lobes of liver
Renal injury assessment
- requires an early phase to assess vascular sufficiency/parenchyma and late phase to assess for extravasation of urine.
Pneumatosis intestinalis
- primary (idiopathic or benign)
- secondary (bowel necrosis, bowel obstruction, IBD, immunosuppression, trauma)
Pancreatitis
- area involved (head, body, tail)
- enhancement -> degree of necrosis
- fat stranding
- look for cause: gall stones (not often seen) or dilated CBD
- look for complications: fluid collections, pseudocyst, abscess, pseudoaneurysm, haemorrhage
Pelvic Fractures
- anteroposterior compression (external rotation of the hemipelvis)
- lateral compression (internal rotation of hemipelvis)
- vertical shear
- complex (a combination of multiple patterns of force)
- if there is more than 2.5cm of pubic rami diastasis there must be additional injury to the posterior ligaments.
TIPS AND TRAPS
- small bowel: more central, plicae circulares (circumferential)
- large bowel: more peripheral, haustra (not circumferential)
- if bowel obstruction seen look for: free air, pneumatosis intestinalis and/or gas in portal vein
- if caecum exceeds 12 cm in diameter -> high risk of perforation and decompression should be considered
- if small bowel > 3cm = distended
- placing the film on lung windows can demonstrate subtle evidence of intra-abdominal free gas
References and Links
LITFL
- Hartung MP. Abdominal CT interpretation course. LITFL
- CCC – AXR Interpretation
- Eponymictionary – Leo George Rigler (1896 – 1979) and Rigler sign (1941)
- Top 10 X-Ray foreign bodies
Journal articles
- James. The Abdominal Radiograph. Ulster Med J 2013;82(3):179-187
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
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