Use of the Learning Curve-Cumulative Summation test for quantitative and individualized assessment of competency of a surgical procedure in obstetrics and gynecology: fetoscopic laser ablation as a model

Learning curve analysis of robot-assisted radical hysterectomy for cervical cancer: initial experience at a single institution

OBJECTIVE

The aim of this study was to evaluate the learning curve and perioperative outcomes of robot-assisted laparoscopic procedure for cervical cancer.

METHODS

A series of 65 cases of robot-assisted laparoscopic radical hysterectomies with bilateral pelvic lymph node dissection for early stage cervical cancer were included. Demographic data and various perioperative parameters including docking time, console time, and total operative time were reviewed from the prospectively collected database. Console time was set as a surrogate marker for surgical competency, in addition to surgical outcomes. The learning curve was evaluated using cumulative summation method.

RESULTS

The mean operative time was 190 minutes (range, 117 to 350 minutes). Two unique phases of the learning curve were derived using cumulative summation analysis; phase 1 (the initial learning curve of 28 cases), and phase 2 (the improvement phase of subsequent cases in which more challenging cases were managed). Docking and console times were significantly decreased after the first 28 cases compared with the latter cases (5 minutes vs. 4 minutes for docking time, 160 minutes vs. 134 minutes for console time; p<0.001 and p<0.001, respectively). There was a significant reduction in blood loss during operation (225 mL vs. 100 mL, p<0.001) and early postoperative complication rates (28% vs. 8.1%, p=0.003) in phase 2. No conversion to laparotomy occurred.

CONCLUSION

Improvement of surgical performance in robot-assisted surgery for cervical cancer can be achieved after 28 cases. The two phases identified by cumulative summation analysis showed significant reduction in operative time, blood loss, and complication rates in the latter phase of learning curve.

Characterizing the learning curve of the VBLaST-PT(©) (Virtual Basic Laparoscopic Skill Trainer)

BACKGROUND

Mastering laparoscopic surgical skills requires considerable time and effort. The Virtual Basic Laparoscopic Skill Trainer (VBLaST-PT(©)) is being developed as a computerized version of the peg transfer task of the Fundamentals of Laparoscopic Surgery (FLS) system using virtual reality technology. We assessed the learning curve of trainees on the VBLaST-PT(©) using the cumulative summation (CUSUM) method and compared them with those on the FLS to establish convergent validity for the VBLaST-PT(©).

METHODS

Eighteen medical students from were assigned randomly to one of three groups: control, VBLaST-training, and FLS-training. The VBLaST and the FLS groups performed a total of 150 trials of the peg-transfer task over a 3-week period, 5 days a week. Their CUSUM scores were computed based on predefined performance criteria (junior, intermediate, and senior levels).

RESULTS

Of the six subjects in the VBLaST-training group, five achieved at least the "junior" level, three achieved the "intermediate" level, and one achieved the "senior" level of performance criterion by the end of the 150 trials. In comparison, for the FLS group, three students achieved the "senior" criterion and all six students achieved the "intermediate" and "junior" criteria by the 150th trials. Both the VBLaST-PT(©) and the FLS systems showed significant skill improvement and retention, albeit with system specificity as measured by transfer of learning in the retention test: The VBLaST-trained group performed better on the VBLaST-PT(©) than on FLS (p = 0.003), whereas the FLS-trained group performed better on the FLS than on VBLaST-PT(©) (p = 0.002).

CONCLUSIONS

We characterized the learning curve for a virtual peg transfer task on the VBLaST-PT(©) and compared it with the FLS using CUSUM analysis. Subjects in both training groups showed significant improvement in skill performance, but the transfer of training between systems was not significant.

Using the CUSUM test to control the proportion of inadequate open biopsies of musculoskeletal tumors

BACKGROUND

Biopsies of musculoskeletal tumors lead to alterations in treatment in almost 20% of cases. Control charts are useful to ensure that a process is operating at a predetermined level of performance, although their use has not been demonstrated in assessing the adequacy of musculoskeletal biopsies.

QUESTIONS/PURPOSES

We therefore (1) assessed the incidence of and the reasons for inadequate musculoskeletal biopsies when following guidelines for performing the procedure; and (2) implemented a process control chart, the CUSUM test, to monitor the proportion of inadequate biopsies.

METHODS

We prospectively studied 116 incisional biopsies. The biopsy was performed according to 10 rules to (1) minimize contamination in the tissues surrounding the tumor; and (2) improve accuracy. A frozen section was systematically performed to confirm that a representative specimen was obtained. Procedures were considered inadequate if: (1) another biopsy was necessary; (2) the biopsy tract was not appropriately placed; and (3) the treatment provided based on the diagnosis from the biopsy was not appropriate.

RESULTS

Five (4.3%) of the 116 incisional biopsy procedures were considered failures. Three patients required a second repeat open biopsy and two were considered to receive inappropriate treatment. No alarm was raised by the control chart and the performance was deemed adequate over the monitoring period.

CONCLUSIONS

The proportion of inadequate musculoskeletal open biopsies performed at a referral center was low. Using a statistical process control method to monitor the failures provided a continuous measure of the performance.

Intrauterine surgery--choices and limitations

BACKGROUND

The past decade has seen much progress in intrauterine surgery. Randomized trials have documented the benefit of some procedures of this type for the unborn child.

METHOD

Selective literature review

RESULTS

Randomized trials have demonstrated the benefit of fetoscopic laser coagulation of placental anastomoses in twin-to-twin transfusion syndrome (TTTS) and of intrauterine surgery via hysterotomy for the repair of spina bifida. Other fetoscopic procedures have yielded promising initial results but are not yet supported by findings from randomized trials. Some intrauterine surgical procedures must still be considered experimental in view of the lack of randomized trials and the rarity of the conditions they are designed to treat. Fetoscopic laser coagulation for TTTS is by far the most common procedure in fetal surgery; TTTS arises in roughly 1 in 2500 pregnancies. The other procedures discussed in this article are performed much less often and for rarer indications. In general, intrauterine surgery is indicated only to treat conditions that would otherwise lead to intrauterine death or irreversible prenatal damage.

CONCLUSION

Intrauterine surgery is a rapidly developing field. Prenatal intervention by laser coagulation is indicated to treat severe TTTS, as its benefit has been shown in a randomized trial. Not enough evidence is yet available for the possible benefit of intrauterine surgery to treat myelomeningocele and congenital diaphragmatic hernia. Other indications are experimental. When an indication for intrauterine surgery exists, the parents should be informed and, depending on their wishes, referred to a center where it can be performed.

Cerclage for cervical shortening at fetoscopic laser photocoagulation in twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to evaluate the benefit of cervical cerclage for cervical length ≤ 25 mm at the time of fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome.

STUDY DESIGN

A multicenter, retrospective cohort study was conducted with 163 patients with a short cervix before FLP for twin-twin transfusion syndrome. Seventy-nine of the patients (48%) had cerclage placement at the surgeon's discretion. The outcome measures that were compared were gestational age at delivery and perinatal mortality rates for patients with cerclage and those who were treated conservatively. Outcomes were evaluated with the use of comparative statistics.

RESULTS

There were no differences in the preoperative variables, except cerclage was performed more frequently for a cervical length of ≤ 15 mm (P < .001). There were no differences in the gestational age at delivery (28.8 ± 5.4 vs 29.1 ± 5.6 weeks with and without cerclage, respectively; P = .15); perinatal mortality rates were similar between the 2 groups.

CONCLUSION

The benefit of cerclage for patients with short cervix before FLP remains questionable.