Abdominal imaging Flashcards
AXR basics.
a) 2 types
b) Adequate exposure
a) AP erect and AP supine
b) Diaphragm to pelvis
AXR interpretation: systematic approach.
- BBC
- Bowels and other organs
- Bones
- Calcifications and stones
Abdominal XR.
a) Ureteric stones - appearance
b) Main differential? - distinguishing features
a) Calcium oxalate (80%) - radiopaque, elongated, craggy edges
b) Phleboliths - calcified deposits in veins - rounder and smoother than ureteric stones
Abdominal XR.
- Small bowel obstruction vs LBO
- SBO - more central, valvulae conniventes (beaded appearance - traverse entire width of bowel)
- LBO - more peripheral, haustra (only partly traverse the width of bowel), larger
Abdominal XR.
a) Appearance of faeces
b) In constipated patient, what may you see?
a) Mottled appearance - due to gas trapped within the solid faeces. Often visible in the colon
b) Impacted solid faeces in the rectum/ colon
Volvulus.
a) Define
b) 2 most common (in adults) and their classic appearance on AXR
c) Type in infants
a) Volvulus is a twisting of the bowel on its mesentery
b) - Sigmoid volvulus: ‘coffee bean’ appearance
- Caecal volvulus: foetal appearance
c) - Midgut malrotation - presents with bilious vomiting. Requires Ladd’s procedure
Bowel obstruction.
a) Threshold widths for the SI, LI and caecum
b) Dilatation above how many cm is a high risk for imminent rupture?
c) Gas in the rectum - significance?
a) 3cm - small intestine
6cm - Large intestine
9cm - caecum
b) 10 cm
c) In the context of bowel obstruction…
- If there is gas in the rectum, there is only a partial obstruction
- If no gas is seen in the rectum, the obstruction is complete
Bowel obstruction.
a) 4 cardinal clinical features of bowel obstruction
b) Management
a) Absolute constipation
Abdominal pain
Abdominal distension
Vomiting
b) - CT or AXR to diagnose obstruction (CT better than XR for seeing where the obstruction is)
- May do CXR to assess for perforation (pneumoperitoneum)
- Drip (IV fluids) and suck (NG tube)
- Avoid AKI (dehydration common due to loss of fluid via vomiting/ NG losses, and also due to lack of water reabsorption in the colon)
Perforated viscus.
a) If worried about bowel perforation, what radiograph should be ordered?
b) What is the differential for pneumoperitoneum
Erect CXR
- look for pneumoperitoneum (air under the diaphragm)
b) Chilaiditi sign
- bowel below diaphragam (haustra visible)
- due to chronic constipation and faecal impaction - give an enema
IBD features on AXR.
- Thumb-printing – mucosal thickening of the haustra due to inflammation and oedema causing them to appear like thumb prints projecting into the lumen
- Lead-pipe (featureless) colon – loss of normal haustral markings secondary to chronic colitis
- Toxic megacolon – colonic dilatation without obstruction associated with colitis
Gallbladder on AXR.
- possible findings
- Gallstones (if calcified)
- Post-cholecystectomy clips
Bones visible on AXR
- Ribs
- Vertebrae: Lumbar, Sacrum, Coccyx
- Pelvis
- Proximal femurs
Calcifications visible on AXR (and other visible paraphernalia)
- Calcified gallstones in the RUQ
- Renal stones/staghorn calculi
- Pancreatic calcification
- Vascular calcification (eg. phleboliths)
- Costochondral calcification
- Contrast (eg. following a barium meal)
- Surgical clips (eg. post-cholecystectomy)
- Ureteric stents
- Naval jewellery artefact over the approximate location of the umbilicus
Ureteric stones on AXR.
a) Where do they commonly lodge? (3)
b) If not visible on XR, gold standard is…?
a) - Uretopelvic junction (UPJ)
- Pelvic brim
- Vesico-ureteric junction (at level of ischial spines)
b) Non-contrast CT KUB
Phleboliths vs. ureteric calculi
Phleboliths - rounder and more homogenous
