Abdominal plain film image interpretation is one of those areas of medical imaging that is widely considered by radiographers to be confusing and unmasterable. There are many reasons for this perception

• It is confusing
• Abdominal plain film interpretation has an accuracy of between 55 and 80%
• Images often don't have meaning without a clinical context (but not always)
• Radiographers are not trained in image interpretation to the same level as radiologists
• It requires sustained effort to master

• You need a radiologist mentor

Despite these formidable difficulties, radiographers can master abdominal plain film image interpretation to a very high level. This page looks at one of these obstacles- the importance of a clinical context.

A significant aid to understanding the role of the abdominal plain film is to consider it in its clinical context. Looking at an abdominal plain film with no clinical information is often like looking at the abdominal plain film image below.

It would be brave person who would offer a firm diagnosis on the abdominal plain film above!

I have a colleague who suggests that an abdominal plain film is a bit like taking a patient's temperature. A patient with a significantly high temperature indicates that the patient is unwell, but is highly unlikely to throw up a diagnosis in isolation.

Some abdominal plain films are only able to be given meaning in the context of all of what the clinician knows about the patient. Whilst each of the four sources of information shown below may suggest a diagnosis, the likelihood of correct diagnosis will require a consideration of all four findings.

No Clinical Context In the absence of any other information, all you can say about this patient's abdominal image is that there are several prominent central loops of gas-filled small bowel. These loops of small bowel happen to look quite odd in that they appear concentric. This is probably just a chance event. They do not have the randomness of normal small bowel but equally are not dilated. Clinical Context Patient has renal colic Other Imaging The patient proceeded to have a CT abdomen where a 5.4cm left renal stone was found with left upper renal tract obstruction with moderate left hydronephrosis. Comment In the absence of any other patient information, this image suggests nothing specific. Knowing that the patient has renal colic raises the possibility that the patient has a reflex ileus which is causing the prominent small bowel loops. The renal stone and hydronephrosis found on CT support this finding.

Supine Image There is a paucity of bowel gas. This could be normal but might also be caused by a variety of pathologies including obstruction The colon is not clearly visualised. This may be normal or may be caused by an obstruction or previous colectomy . It is also possible that the patient has diarrhoea and the colon is fluid-filled, although this is not clearly seen. There is no gas in the rectum ? stoma in left iliac fossa ?sacral spina bifida occulta Summary The appearances are not specifically abnormal but are suspicious of an early or low grade small bowel obstruction.

Erect Image There are a few air/fluid levels There are a few gas bubbles that may be caught in small bowel valvulae suggesting SBO There is no gastric fundus air bubble. Summary The erect image is possibly slightly more suggestive of a SBO but is not conclusive.

Patient History

•Crohn's Disease (quiescent at time of presentation)

•Colectomy / ileostomy 1994

•Multiple laparotomies for SBO secondary to adhesions

Clinical Presentation

•Soft abdomen

•Increased bowel sounds (indicative of obstruction)

Blood Test Results

White blood cell count (WBC) •WBC = 15.9 (4.3 - 10.8)

WBC count is the number of white blood cells in a volume of blood. Normal range varies generally between 4,300 and 10,800 cells per cubic millimeter (cmm). This can also be referred to as the leukocyte count and can be expressed in international units as 4.3 - 10.8 x 109 cells per litre

C-Reactive Protein (CRP) •CRP = 2 (normal < 10)

CRP is a plasma protein which increases in patients who have inflammation or infection. CRP is not specific. A high result serves as a general indication of acute inflammation. In a healthy person, CRP is usually less than 10 mg/L. Most infections and inflammations result in CRP levels above 100 mg/L.

Temperature

The patient's temperature is 35.2 An oral temperature between 36.1°C and 37.8°C is considered ‘normal'.

Review

The clinical picture places a completely different perspective on the two abdominal plain film images. This patient has a history of Crohn's disease which is presently quiescent. Patients with Crohn's disease who present with an acute abdomen will commonly have either active Crohn's disease or SBO from adhesions secondary to previous surgery. The patient has a C-reactive protein (CRP) of 2 which does not indicate infection or inflammation. This suggests low grade SBO caused by adhesions as a more likely diagnosis. The failure to demonstrate the large bowel reflects the history of colectomy.

Comment

The patient history and blood results suggest the patient may have a SBO. The plain film appearance is consistent with a low grade or early SBO.