An Approach to the Abdominal X-Ray
Abdominal films are taken commonly in acute surgical patients with abdominal pain or symptoms of intestinal obstruction. This is can be looked at systematically by thinking about the different organ systems seen on the film that may cause abdominal problems. Looking through some films or a text book will show you what these appearances look like and why these questions are important.
1. Check patient details and date the X-ray was performed
2. Side markers
It doesn’t look good if you put a film on the light box the wrong way round… (This is a mistake that is becoming easier to avoid as more hospitals now have computer-based systems)
3. Technical factors
Most abdominal films are taken with the patient spine (lying down) and are Anterior-Posterior (AP) projections. The film should be exposed correctly, and well centred, showing the symphysis pubis, both hip joints and should extend to the level of the diaphragm. Also, there may be medical items visible on the film.
Approach the abdominal film by looking at all the abdominal organ systems in turn.
1. Gastrointestinal system
Is the bowel gas distributed normally? Are there any large loops of bowel that may be dilated? Dilated small bowel measures more than 3 cm, dilated large bowel more than 5 cm. Small bowel loops have valvulae conniventes (small lines that cross the lumen completely) whereas large bowel has haustral folds (these do not cross the lumen.)
2. Liver and Biliary system
Are there gallstones present (N.B. most gallstones are not seen on X-ray)?
The liver outline should usually be visible. Is there hepatomegaly?
3. Pancreas, Aorta (Organs that may be calcified in disease states)
The pancreas may be calcified in chronic pancreatitis.
The aorta may be visible if there is a calcified abdominal aortic aneurysm.
5. Urinary tract
The kidneys may be visible on the plain radiograph. Some urinary tract stones may also be visible. Urinary tract problems may be further investigated radiologically using intravenous contrast.
It’s worth quickly checking for fractures if there is any hint of trauma.