Table of Contents
Introduction
- Patient: name, DOB, hospital number, age, sex
- Previous films for comparison
Radiograph detail
- Date
- Type (supine, upright, lateral decubitus)
- Adequacy
- Area (diaphragm to pelvis)
- Rotation
- Penetration
Upper limits of normal bowel diameters
3-6-9 rule
3cm = small bowel
6cm = large bowel
9cm = caecum and sigmoid
Interpretation (BOB)
Briefly mention obvious abnormalities first.
Bowel
- Small bowel
- Identify by: central position; plicae circulares/valvulae conniventes (mucosal folds that cross the whole width of the bowel)
- Should be <3cm in diameter (enlarged in small bowel obstruction)
- Large bowel
- Identify by: peripheral position; faecal contents; haustra (pouches that protrude into the lumen)
- Should be <6cm in diameter (enlarged in large bowel obstruction)
- Faeces (mottled appearance)
- Gas (normal in fundus and large bowel only): extra-luminal gas indicates perforation; check for gas in rectum if bowel obstruction suspected (presence makes complete obstruction less likely)
- Fluid levels seen in perforation/infection
Other organs
- Soft tissue shadows (may be seen)
- Liver
- Spleen
- Kidneys
- Gallbladder
- Psoas shadow (lost in retroperitoneal inflammation or ascites)
- Calcification of pancreas (chronic pancreatitis), abdominal aorta (atherosclerosis) or renal stones/gallstones
Bones
- Spine and pelvis: Paget’s disease (cotton wool lytic/sclerotic pattern); metastasis (lytic/sclerotic lesions); osteoarthritis (loss of joint space, osteophytes, subchondral sclerosis/cysts); vertebral fractures
To complete
- ‘To complete my analysis, I would examine previous films and ascertain the clinical history.’
- ‘If there is any suspicion of perforation, I would request an erect chest x-ray to look for air under the diaphragm.’
- Summarise and suggest differentials
Common pathology
- Small bowel obstruction: small bowel distension >3cm, no gas in large bowel, fluid levels if erect
- Large bowel obstruction: large bowel distension >6cm
- Toxic megacolon: colonic dilatation without obstruction, associated with colitis
- Volvulus: twisting of bowel on its mesentery, causing coffee-bean appearance if sigmoid volvulus or ‘fetal’ appearance if caecal
- Chronic pancreatitis: pancreatic calcification
- Urinary stones
- Pneumoperitoneum (due to viscus perforation or recent surgery): Rigler’s double wall sign – both sides of bowel wall visible due to air outside the bowel