title: Does the timing of an invasive mesenteric angiography following a positive CT mesenteric angiography make a difference?
abstract: BACKGROUND
  Computed tomographic mesenteric angiography (CTMA) is integral in the management of patients with acute lower gastrointestinal tract bleeding (LGIB). An invasive mesenteric angiography (MA) with a view to embolize the site of bleeding is usually performed if active contrast extravasation was seen on the CTMA scans. However, the bleeding may have ceased by the time the invasive MA is performed. This study aims to identify predictors for active extravasation in invasive MA following a positive CTMA in patients with massive LGIB.
  
  
  METHODS
  A single-center retrospective study of all patients who underwent an invasive MA following a positive CTMA for LGIB from August 2007 to October 2013 was performed. Comparison was performed between patients who had positive and negative invasive MA after a positive CTMA.
  
  
  RESULTS
  Forty-eight invasive MA scans were performed in patients with LGIB following a positive CTMA scan. Twenty-three (47.9%) were due to diverticular disease while 20 (41.7%) bled from the small bowel. The median delay from a positive CTMA to invasive MA was 144 (32-587) min. Of the 48 invasive MA, 25 demonstrated active extravasation. Invasive MA scans that was performed within 90 min after a positive CTMA scan were 8.56 (95% CI 0.96-76.1, p = 0.05) times more likely to detect a positive extravasation.
  
  
  CONCLUSIONS
  Invasive MA should be executed promptly after a positive CTMA to increase the probability of detecting the site of bleed to allow superselective embolization.
authors.affiliation: Division of Colorectal Surgery, University Surgical Cluster, National University Hospital, National University Health System Singapore, 1E Kent Ridge Road, Singapore, 119228, Singapore.
authors.forename: Frederick H
authors.initials: FH
authors.lastname: Koh
authors.forename: Junwei
authors.initials: J
authors.lastname: Soong
authors.forename: Bettina
authors.initials: B
authors.lastname: Lieske
authors.forename: Wai-Kit
authors.initials: WK
authors.lastname: Cheong
authors.forename: Ker-Kan
authors.initials: KK
authors.lastname: Tan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D004621:Embolization, Therapeutic; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000000981:diagnostic imaging* / Q000628:therapy; D006801:Humans; D008297:Male; D008643:Mesentery / Q000000981:diagnostic imaging*; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult