Cholangiography during laparoscopic cholecystectomy--cumulative sum analysis of an institutional learning curve

J Gastrointest Surg. 1999 Mar-Apr;3(2):185-8. doi: 10.1016/s1091-255x(99)80031-6.


The ability to perform intraoperative cholangiography during laparoscopic cholecystectomy is an essential skill for the laparoscopic biliary surgeon. The volume of experience required to be able to consistently obtain a cholangiogram during laparoscopic cholecystectomy has not been determined. Cumulative sum analysis is a statistical technique which generates a graphical display that identifies periods of performance that fall below a predetermined standard for a given task. The cumulative sum (S(n)) for a series of observations is defined as: S(n)= summation operatorX(I) - X(o), where X(I) = 0 for a success, X(I) = 1 for a failure, and X(o) is the acceptable failure rate for the process under study. This function is plotted against the number of observations to create a curve. When the curve has a positive slope, the acceptable failure rate is being exceeded. When it reaches a plateau, the observed failure rate is equal to the acceptable failure rate. When the curve has a negative slope, the observed failure rate is lower than the acceptable failure rate. We performed a cumulative sum analysis of the first 97 intraoperative cholangiograms attempted during lap-aroscopic cholecystectomy at our institution. The results demonstrated that 46 cases were required to reach a level of proficiency where a cholangiogram could be obtained in 95% of attempts. Success rates of 85% and 90% were achieved at 16 and 25 cases, respectively. This form of analysis is a useful tool for estimating the number of attempts required to achieve a desired success rate when learning new procedures.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cholangiography / statistics & numerical data*
  • Cholecystectomy, Laparoscopic* / statistics & numerical data
  • Clinical Competence / statistics & numerical data*
  • Female
  • Gastroenterology / education*
  • Humans
  • Intraoperative Care / statistics & numerical data*
  • Learning
  • Male
  • Middle Aged
  • Registries