RETROPERITONEAL EDEMA - SONOGRAPHIC MIMIC OF RETROPERITONEAL FLUID COLLECTION

Background: The sonographic finding of an anechoic retroperitoneal abn ormality suggests a fluid collection (e.g., abscess, urinoma, hematoma ), Our study was performed to evaluate cases in which this sonographic finding appeared to be a manifestation of systemic edema. Subjects an d Methods: Inpatient sonograms performed over a 40-month period were r eviewed for the presence of anechoic areas suggestive of fluid collect ion in the retroperitoneum of the flank, Records of patients with such findings were reviewed for evidence of retroperitoneal abscess, urino ma, or hemorrhage, as well as for the presence and cause(s) of periphe ral edema. Results: Of the 29 patients identified with sonographic fin dings suspicious for retroperitoneal fluid collection, 13 (45%) had no cause for and no clinical evidence of focal retroperitoneal collectio n, All 13 patients had peripheral edema attributable to hypoalbuminemi a, congestive heart failure, overhydration, cirrhosis, and/or the syst emic inflammatory response (multiple organ failure) syndrome. Resoluti on of the retroperitoneal abnormality following therapy for congestive heart failure was documented in one case, and CT scan confirmed retro peritoneal edema in another. Conclusion: Anechoic regions that represe nt edema can be seen on sonograms of the retroperitoneum in patients w ith conditions that cause edema in other regions. The possibility of e dema mimicking a fluid collection should be particularly considered pr ior to invasive procedures in the retroperitoneum.