title: Learning curve for transanal endoscopic microsurgery: a single-center experience.
abstract: BACKGROUND
  Transanal endoscopic microsurgery (TEM) was first published by the late Professor Buess in 1983. The procedure initially had a slow acceptance due to its perceived difficulty, the cost of the equipment, and limited indications. However, the widespread adoption of laparoscopic colorectal surgery provided an impetus to increase the penetration of the platform. The purpose of this study was to evaluate the TEM learning curve (LC).
  
  
  METHODS
  After institutional review board approval, all patients who underwent TEM, from November 2005 to October 2008 were identified from a prospective database. The operations were performed by a single, board-certified colorectal surgeon (DRS), after learning the technique from Professor Buess. Patient, operative, and postoperative variables were obtained by retrospective chart review. Rates of excision in minutes per cm(2) of tissue were calculated. The CUSUM method was used to plot the LC. Variables were compared using χ (2) and Student's t test. A p < 0.05 was considered significant.
  
  
  RESULTS
  Twenty-three patients underwent TEM (median age 61 years, 69.5 % male). Mean operative time was 130.5 (range 39-254) min, and the mean specimen size was 16.6 (7.4-42) cm(2). Average rate of excision (ARE) was 8.9 min/cm(2). A stabilization of the LC was observed after the first four cases, showing an ARE of 13.8 min/cm(2) for the first four cases versus 7.9 min/cm(2) for the last 19 cases (p = 0.001). An additional rising and leveling of the LC was observed after the first 10 cases, when an increasing number of lesions located cephalad to 8 cm from the dentate line were being resected (lesions above 8 cm in the first 10 cases: 20 % vs. last 13 cases: 61 %; p = 0.04).
  
  
  CONCLUSIONS
  The ARE significantly declined after the first four cases. The LC for TEM is associated with a significant decrease in operative time after four cases.
authors.affiliation: Department of Colorectal Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd, Weston, FL, 33331, USA.
authors.forename: Antonio
authors.initials: A
authors.lastname: Maya
authors.forename: Andrew
authors.initials: A
authors.lastname: Vorenberg
authors.forename: Myrian
authors.initials: M
authors.lastname: Oviedo
authors.forename: Giovanna
authors.initials: G
authors.lastname: da Silva
authors.forename: Steven D
authors.initials: SD
authors.lastname: Wexner
authors.forename: Dana
authors.initials: D
authors.lastname: Sands
mesh_terms: D003107:Colorectal Surgery / Q000193:education* / Q000379:methods*; D004502:Education, Medical, Continuing; D006801:Humans; D059032:Learning Curve; D008866:Microsurgery / Q000193:education*; D057605:Natural Orifice Endoscopic Surgery / Q000193:education*; D061646:Operative Time; D012371:Robotics