Analysis Of The Learning Curve In The Treatment Of Uterine Fibroids With High Intensity Focused Ultrasound

Uterine fibroids are the most common solid tumors of the female reproductive system. High intensity focused ultrasound(HIFU) cause coagulation necrosis of the target tissue by focused ultrasound beam, it results in symptomatic relief and solution, and has no damage to tissues and organs around the uterus, such as bladder, rectum and ovary. As HIFU changed the traditional surgical approach, has its own special surgical equipment, and highly depend on ultrasound imaging recognition,dissemination of this new technology requires skill training. The discussion of the learning curve for surgery is conducive to evaluate the operator and the technology development trend. Learning curve is a graphical display of the data, and consists of three parts: the starting point, the slope, and the plateau. Starting point maybe the individual experiences or initial level of a new procedure. Slope reflects the individual operation skill or technology improvement. When outcome measures change being measured is not significant, the plateau is arrived. Learning curve analysis helps surgical research and training. Cumulative sum(CUSUM) is a graphical method forquality control. It converts the raw data into accumulated deviations, and displays data change trend intuitional. Cumulative sum for learning curve(LC-CUSUM) deforms from CUSUM, it helps to determine whether the surgical procedure has reached the expected level.The purpose of this paper is to investigate the learning curve of HIFU for the treatment of uterine fibroids by LC-CUSUM and CUSUM, and evaluate the technology development of HIFU, and describing outcome measures to determine whether the trainee reach the expected level or not.ObjectiveBased on the data of ultrasound ablation database, we aim to investigate the long-term learning curve and initial learning curve by analyzing the single-center and multi-center data of high intensity focused ultrasound for the treatment of uterine fibroids.Methods1. From October 2006 to December 2014, one thousand seven hundred and nineteen patients underwent HIFU for uterine fibroids at First Affiliated Hospital of Chongqing Medical University were evaluated. The learning curve then was used to explore the ultrasound ablation surgical method and decision by LC-CUSUM.2. From a multi-center study of uterine fibroids network information system, we extract the initial treatment centers and 360 patients were enrolled, 60 patients in each group. The learning curve was analyzed usingcumulative sum for learning curve(LC-CUSUM) method.Results1. 1712 patients with uterine fibroids undergoing ultrasound ablation at First Affiliated Hospital of Chongqing Medical University. The LC-CUSUM signaled at the 45 th procedure, and CUSUM signaled 41 times thereafter. The length of treatment was 167.57±77.50 min in phase one, 118.03±62.73 min in phase two and 100.17±51.58 min in phase three(P<0.05). The lengths of sonication were 35.35±20.99 min in phase one,26.01±17.10 min in phase two and 20.49±13.23 min in phase three(P<0.05). The mean volume ablation rate in phase one obviously lower than that in phase two and three(P<0.05), no significant difference was found in phase two and three(P=0.456). According to the SIR classification system, 92.67% of the reactions were graded as Class A,2.79% of the reactions were Class B, 4.19% of the reactions were Class C,and 0.35% of the reactions were Class D.2. Six centers enrolled,and the LC-CUSUM signaled at the 14.67±3.88( 11~21) procedure, indicating that sufficient evidence had accumulated to prove that the doctor was competent. Two centers appeared alarm during CUSUM. Mean volume ablation rate was 89.02±13.94%,significant difference was found in each centers(P<0.05). According to the SIR classification system, 242(67.22%) of the reactions were graded as Class A, 28(7.77%) as Class B. No Class C-F reactions.Conclusion1. The technology for HIFU in the treatment of uterine fibroids is stable, and there is a learning rule for it.2. The long term learning curve in ultrasound ablation of uterine fibroids including early exploration stage, technical adjustment stage and stabilization stage. HIFU is a safe and reliable procedure, and has stable and mature technology.3. For a gynecologist and ultrasound physician who has 5 above years’ experience, the initial learning phase completed after the experience of 11 to 21 cases. For a trainee, the non-perfused volume ratio of the subserous myoma located in the lateral wall may be less than 70%.