Computed tomography of fluid collections within the abdomen.

Computed tomography is ideally suited for detecting mass lesions and for distinguishing "solid" from "cystic" masses. In the majority of cases, the recognition of fluid collections is unequivocal and lead to direct management decisions. Subphrenic, intrahepatic, and subhepatic abscesses can be recognized, aspirated, and drained. Using CT control, pancreatic pseudocysts can be managed similarly. Renal cysts can be accurately diagnosed with CT, especially with contrast enhancement, and then even the occasional case in which hydronephrosis may be a problem can be distinguished. Very occasionally, solid tumors containing mucinous material or lipoid can appear as cystic lesions, especially in the suprarenal, ovary, liver, or lymph nodes, and, conversely, abscesses may have higher tissue attenuation values, suggesting a solid lesion. It is most important to ensure that bowel is adequately labeled with contrast so that is is not misdiagnosed as a mass lesion.