title: The current role of intraoperative ultrasound during the resection of colorectal liver metastases: A retrospective cohort study.
abstract: BACKGROUND
  Liver resections with negative margins improve survival in patients with colorectal liver metastases (CRLM). Intraoperative ultrasound (IOUS) is a valuable tool that gives information about lesions that ultimately changes surgical strategy to ensure complete removal, which subsequently improves disease free survival (DFS).
  
  
  METHODS
  A retrospective review of patients who underwent a resection for CRLM from 2009 to 2012 was completed to determine the impact of IOUS.
  
  
  RESULTS
  A total of 103 patients had a hepatic resection for CRLM. All patients had preoperative imaging to assist with operative planning. IOUS was performed in 72 cases. Surgical strategy changed in 31 (43.1%) cases with IOUS, compared to three (9.7%) with no IOUS (P < 0.001). A new lesion was detected in 13 (18.1%) of the cases. A higher proportion of nonanatomic liver resections were performed in the IOUS group (N = 27, 37.5%) compared to the non-IOUS group (N = 6, 19.4%) (P = 0.07).
  
  
  CONCLUSIONS
  Achievement of a negative resection margin was comparable between the two groups. However, there was a trend toward improved DFS in the IOUS group. Despite advances in preoperative imaging, IOUS demonstrates utility in providing novel information that allows removal of the entire tumor burden, using parenchymal-preserving techniques when feasible, leading to improved DFS.
authors.affiliation: Western University, Division of General Surgery, 339 Windermere Rd, PO Box 5339, London, ON N6A 5A5, Canada. Electronic address: knowlsa@gmail.com.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Knowles
authors.affiliation: Western University, Division of General Surgery, 339 Windermere Rd, PO Box 5339, London, ON N6A 5A5, Canada.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Bertens
authors.affiliation: Mayo Clinic, Division of Gastroenterologic and General Surgery, 15, 1st Street SE 501, Rochester, MN 55904, USA.
authors.forename: Kristopher P
authors.initials: KP
authors.lastname: Croome
authors.affiliation: Western University, Division of General Surgery, 339 Windermere Rd, PO Box 5339, London, ON N6A 5A5, Canada.
authors.forename: Roberto
authors.initials: R
authors.lastname: Hernandez-Alejandro
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006498:Hepatectomy / Q000379:methods*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018084:Ultrasonography, Interventional / Q000706:statistics & numerical data*
keywords: Colorectal cancer; Intraoperative ultrasound; Liver/hepatic metastases