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THE RETROPERITONEUM AND GASTROINTESTINAL TRACT 211
A
B
Figure 8.13 (A) Thickened, hypoechoic bowel wall
(5 mm) in Crohn’s disease. (B) Large Crohn’s abscess
containing gas. (C) Diverticulum arising from the
ascending colon.
C
in the follow-up of rectal cancer, and can detect
early recurrence of disease.
Obstruction
Ultrasound has been found to be helpful in the
investigation of acute obstruction. It can confirm
obstruction, by demonstrating dilated, fluidfilled
bowel loops with ineffective peristalsis (Fig.
8.15). These fluid-filled loops of bowel are highly
amenable to ultrasound scanning, which has the
advantage of being able to visualize peristalsis
directly, unlike a plain X-ray. It is possible to trace
the dilated bowel to the site of obstruction, distal
to which are normal loops of collapsed
bowel. 27
The confirmation of obstruction with ultrasound
has been proved to be as sensitive as and
more specific than plain X-rays and can potentially
reduce the need for surgery in such patients, save
costs and reduce radiation dose.
However, identifying the actual site and cause of
obstruction is time-consuming and frequently
unsuccessful. Patients with suspected bowel
obstruction, therefore, usually proceed straight
to CT.