Title: US of the acute abdomen in the era of CT and MRI
Session: Abdomen. Wednesday, October 26th, 1200-1315
Moderator: Bernt Reitan, Haukeland
Room: Agora 1+2, Clarion Hotel Oslo
CT has several advantages over US in the diagnosis of the acute abdomen: CT is extremely rapid, the true costs of CT are probably lower than a time-consuming US examination, CT images are not disturbed by gas and bone, while obesity is even an advantage; producing the CT images is not operator-dependent and CT can be reviewed at a later point in time and even from a distance by means of teleradiology. Finally, CT images are easier understood and accepted by clinicians than US images are.
However, there are also specific advantages of US over CT: US has an image definition in the close range, which is much higher. US is more interactive: patient’s history as well as painful area or palpable mass can be correlated with the US findings. US shows peristalsis, pulsations and blood flow. US shows the effects of respiration, Valsalva manoeuvre, gravity and compression with the probe, allowing to assess whether organs as bowel and gallbladder are soft or rigid. US allows easy puncture of intraperitoneal fluid and drainage of pus.
US in acute abdomen is performed with graded compression. Compression is necessary to displace or compress bowel, eliminating the disturbing influence of bowel gas and to approach the pathological structure closely. This allows using a high frequency transducer with a better image quality. The compression should be graded to avoid unnecessary pain and to avoid pushing organs out of the US plane.
US examination should be symptom-directed and requires communication with the patient. A US finding may lead to a specific question to the patient, and v.v. information provided by the patient may lead to a specific US search for pathology. In patients with an acute abdomen, the entire abdomen should be examined, i.e. from the axilla to the groin. The final US report should be integrated with the clinical findings, laboratory data, CT-scan and possible other radiological examinations.
The US images of appendicitis, diverticulitis, intussusception, acute biliary, urological and gynaecological conditions, infectious ileocolitis, perforated peptic ulcer, small bowel obstruction, pancreatitis, Crohn's disease, epiploic appendagitis, omental infarction and perforating malignancy will be demonstrated using illustrative case histories, with emphasis on the specific advantages of US over CT.