title: Fluorescence Ureteral Visualization in Human Laparoscopic Colorectal Surgery Using Methylene Blue.
abstract: BACKGROUND
  Ureteral injury during laparoscopic surgery is rare, but when it occurs, it can be a serious problem. Near-infrared fluorescence (NIRF) with methylene blue (MB) administration is a promising technique for easier and potentially earlier intraoperative visualization of the ureter. Aim of this prospective study was to assess the feasibility of NIRF imaging of the ureter during laparoscopic colorectal surgery, using MB.
  
  
  METHODS
  Patients undergoing laparoscopic colorectal surgery were included and received intravenous injection of MB preoperatively. The ureter was visualized using a laparoscope, which offered both conventional and fluorescence imaging. Intraoperative recognition of the ureter was registered. The precision of ureter distinction with MB imaging was compared to the conventional laparoscopic view.
  
  
  RESULTS
  Ten patients were included. All procedures were initially performed using a laparoscopic approach. Dose per injection ranged between 0.125 mg/kg and 1.0 mg/kg bodyweight. There were no adverse effects attributable to MB administration. The ureter was successfully detected in five patients, with highest contrast between ureter and surrounding tissue at an administered dose of 0.75-1.0 mg/kg. The fluorescent signal was only picked up after the ureter was already visible in the conventional white light mode.
  
  
  CONCLUSIONS
  Ureteral fluorescence imaging using MB proved to be safe and feasible. However, the present technique does not provide practical advantage over conventional laparoscopic imaging for identification of the ureter during laparoscopic colorectal surgery. Future research is necessary to explore more extensive dose finding, alternative fluorescent dyes, or improvement of the imaging system to make this application clinically beneficial.
authors: Department of Surgery, Maastricht University Medical Center , Maastricht, The Netherlands .
authors: Mahdi
authors: M
authors: Al-Taher
authors: Department of Surgery, Maastricht University Medical Center , Maastricht, The Netherlands .
authors: Jacqueline
authors: J
authors: van den Bos
authors: Department of Surgery, Maastricht University Medical Center , Maastricht, The Netherlands .
authors: Rutger M
authors: RM
authors: Schols
authors: Department of Surgery, Maastricht University Medical Center , Maastricht, The Netherlands .
authors: Nicole D
authors: ND
authors: Bouvy
authors: Department of Surgery, Maastricht University Medical Center , Maastricht, The Netherlands .
authors: Laurents P S
authors: LP
authors: Stassen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003107:Colorectal Surgery; D013505:Digestive System Surgical Procedures / Q000379:methods*; D005260:Female; D005453:Fluorescence; D005456:Fluorescent Dyes; D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control*; D007430:Intraoperative Care; D007431:Intraoperative Complications / Q000517:prevention & control*; D020706:Laparoscopes; D010535:Laparoscopy / Q000379:methods*; D008297:Male; D008751:Methylene Blue; D008875:Middle Aged; D061848:Optical Imaging / Q000379:methods*; D011446:Prospective Studies; D014513:Ureter / Q000293:injuries*
chemical_list: D005456:Fluorescent Dyes; D008751:Methylene Blue
keywords: laparoscopic colorectal surgery; methylene blue; near-infrared fluorescence imaging; ureter; urology