title: Morphology of small aneurysms: definition and impact on risk of rupture.
abstract: BACKGROUND
  Parietal characteristics of small aortic aneurysms predictive of increased risk of rupture are unknown.
  
  
  METHODS
  Prospective morphologic evaluation was performed in 135 consecutive cases of small (< 5 cm) abdominal aortic aneurysm. Twelve cases (9%) were found to be ruptured and sent for emergency surgery. The remaining 123 patients were evaluated with ultrasonography, angiography, and intraoperatively during elective surgery. Ninety-six (78%) also underwent computerized tomography (CT) scanning. The evaluation assessed the thickness of the endoluminal thrombus and arterial wall as well as the presence of saccular outpouchings ("blisters"). Also noted were any areas of impending rupture, defined as discontinuity of the arterial wall with only a thrombus preventing rupture.
  
  
  RESULTS
  Blisters were discovered intraoperatively in 12 aneurysms. Digital subtraction angiography (DSA) revealed 3 (25%) of these preoperatively. Eleven of the patients with blisters were examined preoperatively with CT scanning, which detected 3 blisters (27%). Both endoluminal thrombus and wall thickness were measurable by CT scan but not ultrasonography. The incidence of impending rupture was significantly greater in patients with blisters than in those without (71% versus 29%, P = 0.0001). The incidence of impending rupture was similar whether the amount of endoluminal thrombus was more or less than 2 cm (57% versus 40%, P = 0.386). Rupture was no more frequent when aneurysmal walls were thicker or thinner than 0.3 cm (14% versus 20%, P = 0.719). In an analysis using logistic regression, the presence of a blister was the only independent morphologic predictor of impending rupture (P = 0.001, Wald = 15).
  
  
  CONCLUSIONS
  In patients with small aneurysms, increased attention should be directed to the preoperative detection of blisters.
authors.affiliation: Department of Vascular Surgery, University of Bologna, Italy.
authors.forename: G L
authors.initials: GL
authors.lastname: Faggioli
authors.forename: A
authors.initials: A
authors.lastname: Stella
authors.forename: M
authors.initials: M
authors.lastname: Gargiulo
authors.forename: S
authors.initials: S
authors.lastname: Tarantini
authors.forename: M
authors.initials: M
authors.lastname: D'Addato
authors.forename: J J
authors.initials: JJ
authors.lastname: Ricotta
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D001019:Aortic Rupture / Q000175:diagnosis / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D001027:Aortography; D004630:Emergencies; D005260:Female; D006801:Humans; D015994:Incidence; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013927:Thrombosis / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography