title: Retroperitoneal collections--aetiology and radiological implications.
abstract: OBJECTIVE
  Retroperitoneal collections related to the psoas, in the absence of pancreatitis, are uncommon. This study reviews the imaging, pathogenesis and management of retroperitoneal collections with particular emphasis on distinguishing imaging features and the role of percutaneous drainage.
  
  
  METHODS
  Twenty-three retroperitoneal collections in 22 patients were reviewed in a 2-year period. Twenty-one patients underwent computed tomography (CT), with ultrasound (US) conducted in 14 and magnetic resonance imaging (MRI) in four. The clinical history and associated aetiological factors were noted. Methods of drainage were compared, pathological/microbiological results were recorded and the clinical outcome noted.
  
  
  RESULTS
  The mean age of presentation was 46.9 years (range 18-85 years). There was a male to female preponderance (17 to 6). Eighteen collections proved to be abscesses with five haematomas confirmed. Of the abscesses, three were primary and 15 were secondary to spinal, gastrointestinal or renal disease. Escherichia coli was the commonest isolated organism followed by Mycobacterium tuberculosis. No haematomas were drained. Twelve abscesses were drained successfully by percutaneous methods; three were managed with antibiotics alone; three were managed surgically.
  
  
  CONCLUSIONS
  Secondary abscesses predominate and investigation should be directed at excluding a gastrointestinal or renal source. Tuberculous disease remains a significant problem. Percutaneous drainage allows effective management, even in the presence of a secondary abscess.
authors.affiliation: Department of Radiology, King's College Hospital, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Paley
authors.forename: P S
authors.initials: PS
authors.lastname: Sidhu
authors.forename: R A
authors.initials: RA
authors.lastname: Evans
authors.forename: J B
authors.initials: JB
authors.lastname: Karani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004322:Drainage; D005122:Exudates and Transudates / Q000000981:diagnostic imaging*; D005260:Female; D006406:Hematoma / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D016659:Psoas Abscess / Q000000981:diagnostic imaging* / Q000628:therapy; D016658:Psoas Muscles / Q000000981:diagnostic imaging; D012187:Retroperitoneal Space / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed