Gastrointestinal ImagingAbscess
localized collection of pus. It may be caused by
inflammation, infection, perforation or
trauma of visceral organs or may develop following intra-abdominal surgery. Radiological imaging is based on radiography, including plain films and contrast studies,
ultrasound,
CT and
nuclear imaging. Radiologic imaging will allow a correct diagnosis in the very large majority of patients. Direct radiologic signs of intra-abdominal abscess include: soft tissue mass; loss of normally visualized tissue planes; displacement of intra-abdominal organs; extraluminal gas; and extravasation of contrast medium from the intestinal
lumen.
Among the different diagnostic modalities available CT is the single most sensitive and accurate method. Indirect radiologic signs include: changes in the position and the mobility of the diaphragm; pleural effusion; and signs of hypoventilation or consolidation of the lower lung areas. Radionuclide studies are mainly based on labelling leucocytes with radionuclides such as gallium 67 citrate or indium 111, which collect at the site of the abscess, creating a hot spot. Gallium scans are quite sensitive but rather less nonspecific than indium scans as the gallium may also be taken up by tumours, wounds and postoperative sites. Radionuclide studies should be considered as complementary to the radiological cross-sectional methods. They should be applied in patients with unclear clinical findings in order to assess an area of suspicion, which can be explored further by ultrasound and CT. See also abscess abdominal wall, abscess anorectal, etc. for the abscess of a specific organ.
ALB