title: The "flat cava" sign revisited: what is its significance in patients without trauma?
abstract: OBJECTIVE
  The purpose of this study was to evaluate the clinical significance of the "flat cava" sign on abdominal CT scans in hospitalized patients without trauma.
  
  
  METHODS
  CT scans of the abdomen of 500 inpatients imaged for a wide variety of nontraumatic indications were retrospectively reviewed for a flat cava sign. Two radiologists measured the maximal anteroposterior and transverse diameters of the inferior vena cava at four predetermined levels. The medical records of the subset of patients with a flat cava sign--defined as a maximal transverse-to-anteroposterior ratio of 3:1 or greater at one or more of the four levels--were reviewed for evidence of hypovolemia or hypotension.
  
  
  RESULTS
  Seventy patients (14%; 48 women, 22 men) had a flat inferior vena cava present on at least one of the four levels. Of these 70 patients, 21 had definite and three had possible clinical evidence of hypotension or hypovolemia. A flat cava sign isolated to only one level was seen in 22 of the 70 patients, most commonly at the level just below the renal veins, and only four of these 22 patients had evidence of hypotension or hypovolemia.
  
  
  CONCLUSIONS
  Of the 500 inpatients, 14% had a flat cava sign on at least one of the four levels examined on abdominal CT scans. The majority of these patients with a flat cava sign did not have hypotension or evidence of hypovolemia, but a minority (30%) did.
authors.affiliation: Department of Radiology, Winthrop University Hospital, 259 First St., Mineola, NY 11501, USA.
authors.forename: Recha S
authors.initials: RS
authors.lastname: Eisenstat
authors.forename: Allen C
authors.initials: AC
authors.lastname: Whitford
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lane
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Katz
mesh_terms: D000007:Abdominal Injuries / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007022:Hypotension / Q000000981:diagnostic imaging* / Q000209:etiology; D020896:Hypovolemia / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging*