Original Article
Learning Curve Analysis and Surgical Outcomes of Single-port Laparoscopic Myomectomy Hee Jun Lee, MD1, Ju Yeong Kim, MD1, Seul Ki Kim, MD, Jung Ryeol Lee, MD, PhD*, Chang Suk Suh, MD, PhD, and Seok Hyun Kim, MD, PhD From the Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea (Drs. H.J. Lee, J.Y. Kim, S.K. Kim, J.R. Lee, and C.S. Suh), and Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea (Drs. J.R. Lee, C.S. Suh, and S.H. Kim).
ABSTRACT Study Objective: To identify learning curves for single-port laparoscopic myomectomy (SPLM) and evaluate surgical outcomes according to the sequence of operation. Design: A retrospective study. Setting: A university-based hospital (Canadian Task Force classification II-2). Patients: The medical records from 205 patients who had undergone SPLM from October 2009 to May 2013 were reviewed. Because the myomectomy time was significantly affected by the size and number of myomas removed by SPLM, cases in which 2 or more of the myomas removed were .7 cm in diameter were excluded. Furthermore, cases involving additional operations performed simultaneously (e.g., ovarian or hysteroscopic surgery) were also excluded. A total of 161 cases of SPLM were included. Interventions: None. Measurements and Main Results: We assessed the SPLM learning curve via a graph based on operation time versus sequence of cases. Patients were chronologically arranged according to their surgery dates and were then placed into 1 of 4 groups according to their operation sequence. SPLM was completed successfully in 160 of 161 cases (99.4%). One case was converted to multiport surgery. Basal characteristics of the patients between the 4 groups did not differ. The median operation times for the 4 groups were 112.0, 92.8, 83.7, and 90.0 minutes, respectively. Operation time decreased significantly in the second, third, and fourth groups compared with that in the first group (p , .001). Proficiency, which is the point at which the slope of the learning curve became less steep, was evident after about 45 operations. Conclusion: Results from the current study suggested that proficiency for SPLM was achieved after about 45 operations. Additionally, operation time decreased with experience without an increase in complication rate. Journal of Minimally Invasive Gynecology (2015) 22, 607–611 Ó 2015 AAGL. All rights reserved. Keywords:
DISCUSS
Laparoendoscopic single-port surgery; Laparoscopic myomectomy; Myoma; Myomectomy; Single port
You can discuss this article with its authors and with other AAGL members at http://www.AAGL.org/jmig-22-4-JMIG-D-14-00566
Use your Smartphone to scan this QR code and connect to the discussion forum for this article now* * Download a free QR Code scanner by searching for ‘‘QR scanner’’ in your smartphone’s app store or app marketplace.
1
The authors declare no conflict of interest.
Supported by a grant (HI12C0055) of the Korea Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea. Corresponding author: Jung Ryeol Lee, MD, PhD, Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, 166 Gumiro, Bundang-Gu, Seongnam, Gyeonggi-do 463-707, Korea. E-mail: [email protected] Submitted November 11, 2014. Accepted for publication January 10, 2015. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2015 AAGL. All rights reserved. http://dx.doi.org/10.1016/j.jmig.2015.01.009
In keeping with the trend toward minimal invasiveness in surgery, the laparoscopic approach has become most common for benign gynecologic surgeries. Since its introduction in gynecology, advancements in surgical instruments and techniques have allowed single-port laparoscopic surgery (SPLS) to be applied to various gynecologic operations, and many studies describing this technique have been published [1–3]. The results of several studies have shown many advantages associated with SPLS, including enhanced cosmetic
608
results, reduced postoperative pain, and noninferior results in intraoperative and postoperative complications [3–10]. However, systemic limitations associated with single-port surgeries, such as limited angles of motion and collisions between instruments, require a greater degree of operator training and experience to achieve the necessary surgical skills. This learning curve phenomenon is well recognized and has even been the focus of a few studies involving single-port gynecologic surgeries. For example, Paek et al [11] reported that proficiency in single-port total laparoscopic hysterectomy was achieved after 40 procedures. Furthermore, Song et al [12] reported that surgical proficiency was not evident in oophorectomy but that 33 cases were sufficient for cystectomy in single-site laparoscopic ovarian surgery. Unlike adnexal surgeries and hysterectomies, the single-port approach to myomectomies is not widely used because of the technical difficulties associated with suturing and knot tying, morcellation, and limited angles of motion and collisions between instruments. Furthermore, there is current controversy about increasing morbidity in cases of unrecognized uterine sarcoma by morcellation in which intra-abdominal dissemination of sarcoma may deteriorate the prognosis [13]. However, the risk of occult uterine sarcoma seems to be extremely low, especially in reproductive-age women; therefore, tissue morcellation can be performed safely and effectively by properly trained and experienced surgeons in appropriately screened and selected patients [13]. A few reports have been published regarding the feasibility of single-port laparoscopic myomectomy (SPLM); however, most of them involved a limited number of cases [14–17]. Additionally, SPLM learning curve analyses have not been conducted in studies assessing other types of single-port laparoscopic surgeries, such as hysterectomies, ovarian cystectomies, and adnexal surgeries [8,11,12]. Recently, a single surgeon performed 205 cases of successful SPLM following the same techniques used in conventional laparoscopic myomectomies in our center. Unlike other benign gynecologic surgeries, myomectomies have a very wide range according to case-by-case characteristics. Operation time, which is an index of the learning curve, can be affected by the size and number of myomas, and these factors may be obstacles in myomectomy learning curve analyses. The purpose of the current study was to confirm the learning curve of SPLM and verify the feasibility and safety of SPLM. Materials and Methods Subjects In this retrospective study that assessed the learning curve associated with SPLM, the medical records from 205 patients who had undergone SPLM from October 2009 to May 2013 performed by 1 operator (J.R.L) at the Seoul National University Bundang Hospital were reviewed. Because the myomectomy time was significantly
Journal of Minimally Invasive Gynecology, Vol 22, No 4, May/June 2015
affected by the size and number of myomas removed by SPLM, cases in which 2 or more of the myomas removed were .7 cm in diameter were excluded. Furthermore, cases involving additional operations performed simultaneously (e.g., ovarian or hysteroscopic surgery) were also excluded. A total of 161 cases of SPLM were included. All basal characteristics including patients’ age, body mass index, number of myomas, diameter of the largest myoma, and weight of the specimen were examined. Additionally, surgical outcomes such as estimated blood loss at operation, differences in hemoglobin levels between operations, mean operation time, duration of postoperative hospital stay, and intraoperative and postoperative complications were assessed. Patients were chronologically arranged according to their surgery dates and were then placed into 1 of 4 groups according to their sequence of operation (Fig. 1). Based on a previous report by Song et al [12], the learning curve of the surgery was evaluated using locally weighted regression (LWR). LWR is a method for fitting a regression surface to data through multivariate smoothing [18]. The dependent variable is smoothed as a function of the independent variables in a moving fashion analogous to how a moving average is computed for a time series. To make the learning curve from 161 spots in Figure 2, we used LWR, which produced a smoothed line that expresses the operative times according to the operation sequence. With this LWR, the statistical method makes a smooth line by applying the weighted least squares method [18]. Proficiency of operation was arbitrarily defined as the point at which the slopes of the LWR curve became less steep abruptly, from the steepest slope. This study was approved by the institutional review board of Seoul National University Bundang Hospital.
Surgical Techniques The procedures were similar to those reported in previous studies [14,19]. In brief, a glove port was made using a surgical glove with commercial trocars while patients were being anesthetized. Two 5-mm trocars (used for forceps and other instruments) were inserted into the third and fifth fingers of the surgical glove, and one 11-mm trocar (used for 10-mm instruments such as myoma screws) was inserted into the thumb of the glove and tied.
Fig. 1 Comparison of operation times between the 4 groups divided according to operation sequence.
Lee et al.
Learning Curve of Single-port Laparoscopic Myomectomy
Fig. 2 The learning curve for single-port laparoscopic myomectomy. The arrow point represents the surgical proficiency. Surgical proficiency was defined as the point at which the slope of the learning curve became less steep and was evident after 45 operations.
609
Pharma, Seoul, Korea) and 9.7 mL normal saline was injected into the tissue adjacent to the base and the capsule of the uterine myoma, an incision was made to the myometrium using a cutting device (Harmonic Scalpel; Ethicon Endo-Surgery, Cincinnati, OH) and was deepened. Then, enucleation of the myoma was accomplished with a myoma screw and claw forceps, and the myometrium was repaired with 1 or 2 layers. Suture tying was accomplished using rigid and articulating instruments intracorporeally. Extraction of the myoma was accomplished using a 15-mm electromechanical morcellator (X-Tract; Ethicon Inc., Somerville, NJ), which was inserted into the index finger of the glove (1 free finger). After irrigation and application of an adhesion barrier (Interceed, Ethicon Inc.), the peritoneum and fascia were closed with a 2-0 Vicryl suture (Ethicon), and the skin was closed by a 3-0 Nylon suture (Ethicon) or compression with a gauze ball.
Statistical Analysis
Patients were placed in the dorsal lithotomy position under general anesthesia. After draping, a uterine manipulator (Rumi System; Cooper Surgical, Trumbull, CT) was inserted in the endometrial cavity using tenaculum forceps and a Hegar dilator. A 2-cm-long intraumbilical incision was made vertically using the open Hassan technique and a wound retractor (Alexis, X-small; Applied Medical, Rancho Santa Margarita, CA) was inserted into the opened umbilicus. The previously made glove port was covered, and a wound retractor was scrolled down to the level of skin. CO2 gas was infused, and a rigid 0 laparoscope and another conventional laparoscopic instrument or an articulating instrument (Real Hand; Novare Surgical Systems, Cupertino, CA; or Autonomy LaparoAngle; Cambridge Endo, Framingham, MA) were inserted into the 5-mm trocars. The overall procedure was similar to the conventional laparoscopic myomectomy procedure. After 10 mL of a solution containing 6 IU (0.3 mL) vasoconstrictor agent (Vasopressin; Hanlim
Regression analysis was used to evaluate the relationship between selected variables and the consecutive cases. Analysis of variance was used to compare the mean of each value among the 4 groups; when a significant difference was identified, the Scheffe post hoc test was applied. All statistical tests were 2 tailed, and all p values ,.05 were considered statistically significant. Data were analyzed using SPSS software, version 20.0 (SPSS Inc., Chicago, IL) and presented as mean 6 standard deviation.
Results One hundred sixty-one patients were included in this cohort. Of the 161 cases, SPLM was completed successfully in 160 (99.4%) cases, and there were no serious intraoperative or postoperative complications. One case required conversion to double ports because of severe adhesion in the pelvic cavity. The patients were divided into 4 groups according to the sequence of operation; each group had the same number of patients (n 5 40) except for group 1 (n 5 41). The mean patient age was 40.7 6 6.6 years, and the mean patient body mass index was 23.0 6 3.3 kg/m2. The characteristics of
Table 1 Characteristics of the patients by sequence of operation Total (N 5 161) Age (yrs) BMI (kg/m2) Diameter of largest myoma (cm) Number of myoma Type of largest myoma, n (%) Intramural Intraligamentary Subserosal Submucosal Weight of specimen (g)
Group 1 (n 5 41)
Group 2 (n 5 40)
Group 3 (n 5 40)
Group 4 (n 5 40)
40.7 6 6.6 23.0 6 3.3 6.9 6 5.9 1.4 6 0.9
39.0 6 7.9 23.5 6 4.4 5.8 6 1.9 1.5 6 1.0
40.7 6 7.6 22.6 6 3.0 6.7 6 2.6 1.4 6 1.1
42.5 6 4.7 23.2 6 2.5 6.6 6 2.0 1.3 6 0.7
40.5 6 5.7 22.7 6 2.9 8.5 6 11.2 1.2 6 0.6
142 (88) 5 (3) 10 (6) 4 (3) 131.6 6 115.6
36 3 1 1 123.4 6 116.3
32 0 5 3 134.8 6 117.9
35 2 3 0 133.2 6 106.9
39 0 1 0 131.5 6 125.1
BMI 5 body mass index. Data are shown as mean 6 standard deviation or number.
p value .13 .60 .21 .53 .26
.99
610
Journal of Minimally Invasive Gynecology, Vol 22, No 4, May/June 2015
Table 2 Surgical outcomes by sequence of operation
Difference of hemoglobin (g/dL) Estimated blood loss (mL) Postoperative hospital stay (day) Mean operation time (min) Conversion to multiport Postop complication Pathologic finding
Total (N 5 161)
Group 1 (n 5 41)
Group 2 (n 5 40)
Group 3 (n 5 40)
Group 4 (n 5 40)
p value
1.8 6 1.0 85.5 6 69.5 2.1 6 0.4 95.2 6 31.9 None None Leiomyoma uteri (n 5 161)
2.0 6 0.9 95.5 6 77.3 2.1 6 0.4 112.0 6 34.9a None None Leiomyoma uteri (n 5 41)
2.0 6 1.2 68.3 6 47.9 2.0 6 0.4 92.8 6 31.6b None None Leiomyoma uteri (n 5 40)
1.8 6 0.9 105.2 6 94.0 2.0 6 0.4 83.7 6 25.9b None None Leiomyoma uteri (n 5 40)
1.6 6 0.9 81.4 6 59.4 2.1 6 0.4 90.0 6 27.3b None None Leiomyoma uteri (n 5 40)
.37 .21 .42 ,.001 d d d
Data are shown as mean 6 standard deviation or number. Values with different superscripts in the same line are significantly different (p , .05).
myoma were evaluated before surgery by transvaginal and transabdominal ultrasonography and confirmed by operation. The mean diameter of the largest myoma was 6.9 6 5.9 cm, and the mean number of myomas was 1.4 6 0.9. The largest myoma was most frequently of the intramural type (88%), and there were no significant differences in basal characteristics between the 4 groups (Table 1). In the comparison of surgical outcomes, such as differences in hemoglobin levels, estimated blood loss, and postoperative hospital stay, no differences were noted among the 4 groups, and all pathologic findings in the 4 groups were leiomyomata uteri (Table 2). The mean operation times of the 4 groups were 112.0, 92.8, 83.7, and 90.0 minutes, respectively. The mean operation times decreased significantly from the first group to the second group (p , .001) and were similar between the second, third, and fourth groups (Fig. 1 and Table 2). The learning curve for SPLM was expressed as operation time according to the sequence of the operation (Fig. 2). LWR analysis indicated that operation time decreased significantly with the sequence of operation (R2 5 0.088, p , .001), and surgical proficiency, defined as the point at which the slope of the learning curve became less steep abruptly from the steepest slope, was achieved after about 45 operations. Discussion SPLS is becoming more popular and widely applied in many areas of gynecologic surgery because of comparable surgical outcomes and even better surgical outcomes in postoperative pain compared with conventional laparoscopic surgery [4–6]. Although cosmetic benefits have been considered the most important advantage of SPLS, reduced potential morbidity associated with multiple skin incisions have also been observed [7,20]. Because the conventional laparoscopic approach to myomectomy requires a larger incision in the left lower quadrant for morcellation, the single-port approach may be more beneficial than other gynecologic procedures because of the
reduced length of the incision and reduced morbidity induced by large incisions, such as incisional hernia or subcutaneous hematoma [21]. However, technical constraints, including limited angles of motion and collisions of instruments, result in difficulties in suturing and tying, and, thus, SPLM can be performed by only skilled surgeons. Therefore, surgeons need more time to become proficient in performing SPLM. These restrictions make it difficult to apply myomectomy using a single-port approach, unlike hysterectomies or other adnexal surgeries. In the current study, the surgical outcomes of 161 SPLM cases were retrospectively analyzed to assess its safety and feasibility. No serious complications were noted, and only 1 case of conversion to double port was required because severe pelvic adhesion. Although some authors have reported learning curves associated with single-port gynecologic surgeries [8,9,11,12], none have reported on the learning curve associated with SPLM. Before evaluating the feasibility of SPLM, concerns about safety-related complications of the procedure, including bowel, ureter, and bladder injury during morcellation, more blood loss, and longer postoperative hospital stay than conventional laparoscopy, were considered. However, after comparing variables examined in our previous study, we noted no differences between conventional laparoscopy and SPLM, as reported by Kim et al [14]. The learning curve associated with an operation reflects the complexity of the surgical procedure. Song et al [12] advocated that the proficiency of cystectomy was achieved after 33 operations, and Paek et al [11] also proved that 40 cases of single-port total laparoscopic hysterectomy were needed to become proficient. In the current study, we proved that about 45 cases of myomectomy enabled a surgeon to become proficient. Surgical proficiency cannot be assessed when the surgical procedure is either very simple or rare. In previous reports comparing single-port oophorectomy with cystectomy, proficiency in oophorectomy, which is a simple surgical procedure, could not be confirmed because the learning curve showed a steady, slow slope [12]. Based on these results, we suggest that simple procedures such as oophorectomy should be attempted at first by inexperienced
Lee et al.
Learning Curve of Single-port Laparoscopic Myomectomy
surgeons in SPLS followed by cystectomy, hysterectomy, and finally myomectomy. To accomplish SPLS, Yang et al [22] suggested training methods. Specialized SPLS training using parallel placement of instruments may allow trainees to become proficient with the procedure. We also suggest that the use of flexible scopes and instruments reduce the time required to become proficient with SPLS. Suturing and knot tying, which can be a hurdle in SPLM as opposed to other single-port adnexal surgeries, can be facilitated by using commercial barbed suture materials. The current study had some limitations. First, all procedures were performed by a single surgeon expert in conventional laparoscopy who performed more than 600 cases of conventional laparoscopic surgery and 12 cases of other SPLS before the first SPLM case and also performed total 778 SPLS cases including 205 SPLM cases during the study period. To prove the validity of the procedure for other surgeons, a multicenter study involving numerous surgeons would be required. Second, the ‘‘real-world’’ operation sequence can be different from the sequence assessed in the current study. We excluded cases involving numerous myomas of large size because the operation time of myomectomy can vary widely based on myoma size and number. This degree of variability in the operation time may affect the learning curve and make it difficult to confirm the proficiency of the operator. Moreover, other single-port surgeries (e.g., oophorectomy or cystectomy) were performed during the current study. Because surgeons can learn more basic skills including traction and retraction while performing these other single-port surgeries, the potential for overlapping proficiency may have been suggested. Third, the slope change portion of the learning curve indicative of proficiency was likely imprecise because it was determined by visual estimate instead of statistical analysis. Although the current study had such limitations, it was the first to report the learning curve associated with SPLM and confirmed the safety and feasibility of SPLM in 161 cases. A randomized controlled trial of SPLM compared with conventional laparoscopic myomectomy in a prospective manner is in progress. In conclusion, SPLS is a modern approach to gynecologic surgery. Although practice and time are needed to become competent in performing SPLM, it is feasible for any surgeon interested in this minimally invasive procedure. It is recommended that SPLS should be attempted in simple procedures at first in order to facilitate familiarity with SPLM.
References 1. Fader AN, Escobar PF. Laparoendoscopic single-site surgery (LESS) in gynecologic oncology: technique and initial report. Gynecol Oncol. 2009;114:157–161.
611 2. Lee YY, Kim TJ, Kim CJ, et al. Single-port access laparoscopic-assisted vaginal hysterectomy: a novel method with a wound retractor and a glove. J Minim Invasive Gynecol. 2009;16:450–453. 3. Kim TJ, Lee YY, Kim MJ, et al. Single port access laparoscopic adnexal surgery. J Minim Invasive Gynecol. 2009;16:612–615. 4. Yim GW, Jung YW, Paek J, et al. Transumbilical single-port access versus conventional total laparoscopic hysterectomy: surgical outcomes. Am J Obstet Gynecol. 2010;203:26e1–26e6. 5. Fagotti A, Bottoni C, Vizzielli G, et al. Postoperative pain after conventional laparoscopy and laparoendoscopic single site surgery (LESS) for benign adnexal disease: a randomized trial. Fertil Steril. 2011;96: 255–259e2. 6. Lee YY, Kim TJ, Kim CJ, et al. Single port access laparoscopic adnexal surgery versus conventional laparoscopic adnexal surgery: a comparison of peri-operative outcomes. Eur J Obstet Gynecol Reprod Biol. 2010;151:181–184. 7. Eom JM, Ko JH, Choi JS, Hong JH, Lee JH. A comparative crosssectional study on cosmetic outcomes after single port or conventional laparoscopic surgery. Eur J Obstet Gynecol Reprod Biol. 2013;167: 104–109. 8. Escobar PF, Starks DC, Fader AN, Barber M, Rojas-Espalliat L. Singleport risk-reducing salpingo-oophorectomy with and without hysterectomy: surgical outcomes and learning curve analysis. Gynecol Oncol. 2010;119:43–47. 9. Fagotti A, Fanfani F, Marocco F, et al. Laparoendoscopic single-site surgery for the treatment of benign adnexal diseases: a pilot study. Surg Endosc. 2011;25:1215–1221. 10. Yoon BS, Park H, Seong SJ, Park CT, Jun HS, Kim IH. Single-port versus conventional laparoscopic salpingectomy in tubal pregnancy: a comparison of surgical outcomes. Eur J Obstet Gynecol Reprod Biol. 2011;159:190–193. 11. Paek J, Kim SW, Lee SH, et al. Learning curve and surgical outcome for single-port access total laparoscopic hysterectomy in 100 consecutive cases. Gynecol Obstet Invest. 2011;72:227–233. 12. Song T, Kim TJ, Lee YY, et al. Learning curves for single-site laparoscopic ovarian surgery. J Minim Invasive Gynecol. 2012;19:344–349. 13. Brown J. AAGL advancing minimally invasive gynecology worldwide: statement to the FDA on power morcellation. J Minim Invasive Gynecol. 2014;21:970–971. 14. Kim SK, Lee JH, Lee JR, Suh CS, Kim SH. Laparoendoscopic singlesite myomectomy versus conventional laparoscopic myomectomy: a comparison of surgical outcomes. J Minim Invasive Gynecol. 2014; 21:775–781. 15. Yoon A, Kim TJ, Lee YY, et al. Laparoendoscopic single-site (LESS) myomectomy: characteristics of the appropriate myoma. Eur J Obstet Gynecol Reprod Biol. 2014;175:58–61. 16. Han CM, Lee CL, Su H, Wu PJ, Wang CJ, Yen CF. Single-port laparoscopic myomectomy: initial operative experience and comparative outcome. Arch Gynecol Obstet. 2013;287:295–300. 17. Kim JY, Kim KH, Choi JS, Lee JH. A prospective matched case-control study of laparoendoscopic single-site vs conventional laparoscopic myomectomy. J Minim Invasive Gynecol. 2014;21:1036–1040. 18. Centner V, Massart DL. Optimization in locally weighted regression. Anal Chem. 1998;70:4206–4211. 19. Lee JH, Lee JR, Jee BC, Suh CS, Kim SH. Safety and feasibility of a single-port laparoscopic adnexal surgery during pregnancy. J Minim Invasive Gynecol. 2013;20:864–870. 20. Escobar PF, Starks D, Fader AN, Catenacci M, Falcone T. Laparoendoscopic single-site and natural orifice surgery in gynecology. Fertil Steril. 2010;94:2497–2502. 21. Kadar N, Reich H, Liu CY, Manko GF, Gimpelson R. Incisional hernias after major laparoscopic gynecologic procedures. Am J Obstet Gynecol. 1993;168:1493–1495. 22. Yang B, Xu B, Zeng Q, et al. A specialized course of basic skills training for single-port laparoscopic surgery. Surgery. 2011;149:766–775.
Learning Curve Analysis and Surgical Outcomes of Single-port Laparoscopic Myomectomy Hee Jun Lee, MD1, Ju Yeong Kim, MD1, Seul Ki Kim, MD, Jung Ryeol Lee, MD, PhD*, Chang Suk Suh, MD, PhD, and Seok Hyun Kim, MD, PhD From the Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea (Drs. H.J. Lee, J.Y. Kim, S.K. Kim, J.R. Lee, and C.S. Suh), and Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea (Drs. J.R. Lee, C.S. Suh, and S.H. Kim).
ABSTRACT Study Objective: To identify learning curves for single-port laparoscopic myomectomy (SPLM) and evaluate surgical outcomes according to the sequence of operation. Design: A retrospective study. Setting: A university-based hospital (Canadian Task Force classification II-2). Patients: The medical records from 205 patients who had undergone SPLM from October 2009 to May 2013 were reviewed. Because the myomectomy time was significantly affected by the size and number of myomas removed by SPLM, cases in which 2 or more of the myomas removed were .7 cm in diameter were excluded. Furthermore, cases involving additional operations performed simultaneously (e.g., ovarian or hysteroscopic surgery) were also excluded. A total of 161 cases of SPLM were included. Interventions: None. Measurements and Main Results: We assessed the SPLM learning curve via a graph based on operation time versus sequence of cases. Patients were chronologically arranged according to their surgery dates and were then placed into 1 of 4 groups according to their operation sequence. SPLM was completed successfully in 160 of 161 cases (99.4%). One case was converted to multiport surgery. Basal characteristics of the patients between the 4 groups did not differ. The median operation times for the 4 groups were 112.0, 92.8, 83.7, and 90.0 minutes, respectively. Operation time decreased significantly in the second, third, and fourth groups compared with that in the first group (p , .001). Proficiency, which is the point at which the slope of the learning curve became less steep, was evident after about 45 operations. Conclusion: Results from the current study suggested that proficiency for SPLM was achieved after about 45 operations. Additionally, operation time decreased with experience without an increase in complication rate. Journal of Minimally Invasive Gynecology (2015) 22, 607–611 Ó 2015 AAGL. All rights reserved. Keywords:
DISCUSS
Laparoendoscopic single-port surgery; Laparoscopic myomectomy; Myoma; Myomectomy; Single port
You can discuss this article with its authors and with other AAGL members at http://www.AAGL.org/jmig-22-4-JMIG-D-14-00566
Use your Smartphone to scan this QR code and connect to the discussion forum for this article now* * Download a free QR Code scanner by searching for ‘‘QR scanner’’ in your smartphone’s app store or app marketplace.
1
The authors declare no conflict of interest.
Supported by a grant (HI12C0055) of the Korea Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea. Corresponding author: Jung Ryeol Lee, MD, PhD, Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, 166 Gumiro, Bundang-Gu, Seongnam, Gyeonggi-do 463-707, Korea. E-mail: [email protected] Submitted November 11, 2014. Accepted for publication January 10, 2015. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2015 AAGL. All rights reserved. http://dx.doi.org/10.1016/j.jmig.2015.01.009
In keeping with the trend toward minimal invasiveness in surgery, the laparoscopic approach has become most common for benign gynecologic surgeries. Since its introduction in gynecology, advancements in surgical instruments and techniques have allowed single-port laparoscopic surgery (SPLS) to be applied to various gynecologic operations, and many studies describing this technique have been published [1–3]. The results of several studies have shown many advantages associated with SPLS, including enhanced cosmetic
608
results, reduced postoperative pain, and noninferior results in intraoperative and postoperative complications [3–10]. However, systemic limitations associated with single-port surgeries, such as limited angles of motion and collisions between instruments, require a greater degree of operator training and experience to achieve the necessary surgical skills. This learning curve phenomenon is well recognized and has even been the focus of a few studies involving single-port gynecologic surgeries. For example, Paek et al [11] reported that proficiency in single-port total laparoscopic hysterectomy was achieved after 40 procedures. Furthermore, Song et al [12] reported that surgical proficiency was not evident in oophorectomy but that 33 cases were sufficient for cystectomy in single-site laparoscopic ovarian surgery. Unlike adnexal surgeries and hysterectomies, the single-port approach to myomectomies is not widely used because of the technical difficulties associated with suturing and knot tying, morcellation, and limited angles of motion and collisions between instruments. Furthermore, there is current controversy about increasing morbidity in cases of unrecognized uterine sarcoma by morcellation in which intra-abdominal dissemination of sarcoma may deteriorate the prognosis [13]. However, the risk of occult uterine sarcoma seems to be extremely low, especially in reproductive-age women; therefore, tissue morcellation can be performed safely and effectively by properly trained and experienced surgeons in appropriately screened and selected patients [13]. A few reports have been published regarding the feasibility of single-port laparoscopic myomectomy (SPLM); however, most of them involved a limited number of cases [14–17]. Additionally, SPLM learning curve analyses have not been conducted in studies assessing other types of single-port laparoscopic surgeries, such as hysterectomies, ovarian cystectomies, and adnexal surgeries [8,11,12]. Recently, a single surgeon performed 205 cases of successful SPLM following the same techniques used in conventional laparoscopic myomectomies in our center. Unlike other benign gynecologic surgeries, myomectomies have a very wide range according to case-by-case characteristics. Operation time, which is an index of the learning curve, can be affected by the size and number of myomas, and these factors may be obstacles in myomectomy learning curve analyses. The purpose of the current study was to confirm the learning curve of SPLM and verify the feasibility and safety of SPLM. Materials and Methods Subjects In this retrospective study that assessed the learning curve associated with SPLM, the medical records from 205 patients who had undergone SPLM from October 2009 to May 2013 performed by 1 operator (J.R.L) at the Seoul National University Bundang Hospital were reviewed. Because the myomectomy time was significantly
Journal of Minimally Invasive Gynecology, Vol 22, No 4, May/June 2015
affected by the size and number of myomas removed by SPLM, cases in which 2 or more of the myomas removed were .7 cm in diameter were excluded. Furthermore, cases involving additional operations performed simultaneously (e.g., ovarian or hysteroscopic surgery) were also excluded. A total of 161 cases of SPLM were included. All basal characteristics including patients’ age, body mass index, number of myomas, diameter of the largest myoma, and weight of the specimen were examined. Additionally, surgical outcomes such as estimated blood loss at operation, differences in hemoglobin levels between operations, mean operation time, duration of postoperative hospital stay, and intraoperative and postoperative complications were assessed. Patients were chronologically arranged according to their surgery dates and were then placed into 1 of 4 groups according to their sequence of operation (Fig. 1). Based on a previous report by Song et al [12], the learning curve of the surgery was evaluated using locally weighted regression (LWR). LWR is a method for fitting a regression surface to data through multivariate smoothing [18]. The dependent variable is smoothed as a function of the independent variables in a moving fashion analogous to how a moving average is computed for a time series. To make the learning curve from 161 spots in Figure 2, we used LWR, which produced a smoothed line that expresses the operative times according to the operation sequence. With this LWR, the statistical method makes a smooth line by applying the weighted least squares method [18]. Proficiency of operation was arbitrarily defined as the point at which the slopes of the LWR curve became less steep abruptly, from the steepest slope. This study was approved by the institutional review board of Seoul National University Bundang Hospital.
Surgical Techniques The procedures were similar to those reported in previous studies [14,19]. In brief, a glove port was made using a surgical glove with commercial trocars while patients were being anesthetized. Two 5-mm trocars (used for forceps and other instruments) were inserted into the third and fifth fingers of the surgical glove, and one 11-mm trocar (used for 10-mm instruments such as myoma screws) was inserted into the thumb of the glove and tied.
Fig. 1 Comparison of operation times between the 4 groups divided according to operation sequence.
Lee et al.
Learning Curve of Single-port Laparoscopic Myomectomy
Fig. 2 The learning curve for single-port laparoscopic myomectomy. The arrow point represents the surgical proficiency. Surgical proficiency was defined as the point at which the slope of the learning curve became less steep and was evident after 45 operations.
609
Pharma, Seoul, Korea) and 9.7 mL normal saline was injected into the tissue adjacent to the base and the capsule of the uterine myoma, an incision was made to the myometrium using a cutting device (Harmonic Scalpel; Ethicon Endo-Surgery, Cincinnati, OH) and was deepened. Then, enucleation of the myoma was accomplished with a myoma screw and claw forceps, and the myometrium was repaired with 1 or 2 layers. Suture tying was accomplished using rigid and articulating instruments intracorporeally. Extraction of the myoma was accomplished using a 15-mm electromechanical morcellator (X-Tract; Ethicon Inc., Somerville, NJ), which was inserted into the index finger of the glove (1 free finger). After irrigation and application of an adhesion barrier (Interceed, Ethicon Inc.), the peritoneum and fascia were closed with a 2-0 Vicryl suture (Ethicon), and the skin was closed by a 3-0 Nylon suture (Ethicon) or compression with a gauze ball.
Statistical Analysis
Patients were placed in the dorsal lithotomy position under general anesthesia. After draping, a uterine manipulator (Rumi System; Cooper Surgical, Trumbull, CT) was inserted in the endometrial cavity using tenaculum forceps and a Hegar dilator. A 2-cm-long intraumbilical incision was made vertically using the open Hassan technique and a wound retractor (Alexis, X-small; Applied Medical, Rancho Santa Margarita, CA) was inserted into the opened umbilicus. The previously made glove port was covered, and a wound retractor was scrolled down to the level of skin. CO2 gas was infused, and a rigid 0 laparoscope and another conventional laparoscopic instrument or an articulating instrument (Real Hand; Novare Surgical Systems, Cupertino, CA; or Autonomy LaparoAngle; Cambridge Endo, Framingham, MA) were inserted into the 5-mm trocars. The overall procedure was similar to the conventional laparoscopic myomectomy procedure. After 10 mL of a solution containing 6 IU (0.3 mL) vasoconstrictor agent (Vasopressin; Hanlim
Regression analysis was used to evaluate the relationship between selected variables and the consecutive cases. Analysis of variance was used to compare the mean of each value among the 4 groups; when a significant difference was identified, the Scheffe post hoc test was applied. All statistical tests were 2 tailed, and all p values ,.05 were considered statistically significant. Data were analyzed using SPSS software, version 20.0 (SPSS Inc., Chicago, IL) and presented as mean 6 standard deviation.
Results One hundred sixty-one patients were included in this cohort. Of the 161 cases, SPLM was completed successfully in 160 (99.4%) cases, and there were no serious intraoperative or postoperative complications. One case required conversion to double ports because of severe adhesion in the pelvic cavity. The patients were divided into 4 groups according to the sequence of operation; each group had the same number of patients (n 5 40) except for group 1 (n 5 41). The mean patient age was 40.7 6 6.6 years, and the mean patient body mass index was 23.0 6 3.3 kg/m2. The characteristics of
Table 1 Characteristics of the patients by sequence of operation Total (N 5 161) Age (yrs) BMI (kg/m2) Diameter of largest myoma (cm) Number of myoma Type of largest myoma, n (%) Intramural Intraligamentary Subserosal Submucosal Weight of specimen (g)
Group 1 (n 5 41)
Group 2 (n 5 40)
Group 3 (n 5 40)
Group 4 (n 5 40)
40.7 6 6.6 23.0 6 3.3 6.9 6 5.9 1.4 6 0.9
39.0 6 7.9 23.5 6 4.4 5.8 6 1.9 1.5 6 1.0
40.7 6 7.6 22.6 6 3.0 6.7 6 2.6 1.4 6 1.1
42.5 6 4.7 23.2 6 2.5 6.6 6 2.0 1.3 6 0.7
40.5 6 5.7 22.7 6 2.9 8.5 6 11.2 1.2 6 0.6
142 (88) 5 (3) 10 (6) 4 (3) 131.6 6 115.6
36 3 1 1 123.4 6 116.3
32 0 5 3 134.8 6 117.9
35 2 3 0 133.2 6 106.9
39 0 1 0 131.5 6 125.1
BMI 5 body mass index. Data are shown as mean 6 standard deviation or number.
p value .13 .60 .21 .53 .26
.99
610
Journal of Minimally Invasive Gynecology, Vol 22, No 4, May/June 2015
Table 2 Surgical outcomes by sequence of operation
Difference of hemoglobin (g/dL) Estimated blood loss (mL) Postoperative hospital stay (day) Mean operation time (min) Conversion to multiport Postop complication Pathologic finding
Total (N 5 161)
Group 1 (n 5 41)
Group 2 (n 5 40)
Group 3 (n 5 40)
Group 4 (n 5 40)
p value
1.8 6 1.0 85.5 6 69.5 2.1 6 0.4 95.2 6 31.9 None None Leiomyoma uteri (n 5 161)
2.0 6 0.9 95.5 6 77.3 2.1 6 0.4 112.0 6 34.9a None None Leiomyoma uteri (n 5 41)
2.0 6 1.2 68.3 6 47.9 2.0 6 0.4 92.8 6 31.6b None None Leiomyoma uteri (n 5 40)
1.8 6 0.9 105.2 6 94.0 2.0 6 0.4 83.7 6 25.9b None None Leiomyoma uteri (n 5 40)
1.6 6 0.9 81.4 6 59.4 2.1 6 0.4 90.0 6 27.3b None None Leiomyoma uteri (n 5 40)
.37 .21 .42 ,.001 d d d
Data are shown as mean 6 standard deviation or number. Values with different superscripts in the same line are significantly different (p , .05).
myoma were evaluated before surgery by transvaginal and transabdominal ultrasonography and confirmed by operation. The mean diameter of the largest myoma was 6.9 6 5.9 cm, and the mean number of myomas was 1.4 6 0.9. The largest myoma was most frequently of the intramural type (88%), and there were no significant differences in basal characteristics between the 4 groups (Table 1). In the comparison of surgical outcomes, such as differences in hemoglobin levels, estimated blood loss, and postoperative hospital stay, no differences were noted among the 4 groups, and all pathologic findings in the 4 groups were leiomyomata uteri (Table 2). The mean operation times of the 4 groups were 112.0, 92.8, 83.7, and 90.0 minutes, respectively. The mean operation times decreased significantly from the first group to the second group (p , .001) and were similar between the second, third, and fourth groups (Fig. 1 and Table 2). The learning curve for SPLM was expressed as operation time according to the sequence of the operation (Fig. 2). LWR analysis indicated that operation time decreased significantly with the sequence of operation (R2 5 0.088, p , .001), and surgical proficiency, defined as the point at which the slope of the learning curve became less steep abruptly from the steepest slope, was achieved after about 45 operations. Discussion SPLS is becoming more popular and widely applied in many areas of gynecologic surgery because of comparable surgical outcomes and even better surgical outcomes in postoperative pain compared with conventional laparoscopic surgery [4–6]. Although cosmetic benefits have been considered the most important advantage of SPLS, reduced potential morbidity associated with multiple skin incisions have also been observed [7,20]. Because the conventional laparoscopic approach to myomectomy requires a larger incision in the left lower quadrant for morcellation, the single-port approach may be more beneficial than other gynecologic procedures because of the
reduced length of the incision and reduced morbidity induced by large incisions, such as incisional hernia or subcutaneous hematoma [21]. However, technical constraints, including limited angles of motion and collisions of instruments, result in difficulties in suturing and tying, and, thus, SPLM can be performed by only skilled surgeons. Therefore, surgeons need more time to become proficient in performing SPLM. These restrictions make it difficult to apply myomectomy using a single-port approach, unlike hysterectomies or other adnexal surgeries. In the current study, the surgical outcomes of 161 SPLM cases were retrospectively analyzed to assess its safety and feasibility. No serious complications were noted, and only 1 case of conversion to double port was required because severe pelvic adhesion. Although some authors have reported learning curves associated with single-port gynecologic surgeries [8,9,11,12], none have reported on the learning curve associated with SPLM. Before evaluating the feasibility of SPLM, concerns about safety-related complications of the procedure, including bowel, ureter, and bladder injury during morcellation, more blood loss, and longer postoperative hospital stay than conventional laparoscopy, were considered. However, after comparing variables examined in our previous study, we noted no differences between conventional laparoscopy and SPLM, as reported by Kim et al [14]. The learning curve associated with an operation reflects the complexity of the surgical procedure. Song et al [12] advocated that the proficiency of cystectomy was achieved after 33 operations, and Paek et al [11] also proved that 40 cases of single-port total laparoscopic hysterectomy were needed to become proficient. In the current study, we proved that about 45 cases of myomectomy enabled a surgeon to become proficient. Surgical proficiency cannot be assessed when the surgical procedure is either very simple or rare. In previous reports comparing single-port oophorectomy with cystectomy, proficiency in oophorectomy, which is a simple surgical procedure, could not be confirmed because the learning curve showed a steady, slow slope [12]. Based on these results, we suggest that simple procedures such as oophorectomy should be attempted at first by inexperienced
Lee et al.
Learning Curve of Single-port Laparoscopic Myomectomy
surgeons in SPLS followed by cystectomy, hysterectomy, and finally myomectomy. To accomplish SPLS, Yang et al [22] suggested training methods. Specialized SPLS training using parallel placement of instruments may allow trainees to become proficient with the procedure. We also suggest that the use of flexible scopes and instruments reduce the time required to become proficient with SPLS. Suturing and knot tying, which can be a hurdle in SPLM as opposed to other single-port adnexal surgeries, can be facilitated by using commercial barbed suture materials. The current study had some limitations. First, all procedures were performed by a single surgeon expert in conventional laparoscopy who performed more than 600 cases of conventional laparoscopic surgery and 12 cases of other SPLS before the first SPLM case and also performed total 778 SPLS cases including 205 SPLM cases during the study period. To prove the validity of the procedure for other surgeons, a multicenter study involving numerous surgeons would be required. Second, the ‘‘real-world’’ operation sequence can be different from the sequence assessed in the current study. We excluded cases involving numerous myomas of large size because the operation time of myomectomy can vary widely based on myoma size and number. This degree of variability in the operation time may affect the learning curve and make it difficult to confirm the proficiency of the operator. Moreover, other single-port surgeries (e.g., oophorectomy or cystectomy) were performed during the current study. Because surgeons can learn more basic skills including traction and retraction while performing these other single-port surgeries, the potential for overlapping proficiency may have been suggested. Third, the slope change portion of the learning curve indicative of proficiency was likely imprecise because it was determined by visual estimate instead of statistical analysis. Although the current study had such limitations, it was the first to report the learning curve associated with SPLM and confirmed the safety and feasibility of SPLM in 161 cases. A randomized controlled trial of SPLM compared with conventional laparoscopic myomectomy in a prospective manner is in progress. In conclusion, SPLS is a modern approach to gynecologic surgery. Although practice and time are needed to become competent in performing SPLM, it is feasible for any surgeon interested in this minimally invasive procedure. It is recommended that SPLS should be attempted in simple procedures at first in order to facilitate familiarity with SPLM.
References 1. Fader AN, Escobar PF. Laparoendoscopic single-site surgery (LESS) in gynecologic oncology: technique and initial report. Gynecol Oncol. 2009;114:157–161.
611 2. Lee YY, Kim TJ, Kim CJ, et al. Single-port access laparoscopic-assisted vaginal hysterectomy: a novel method with a wound retractor and a glove. J Minim Invasive Gynecol. 2009;16:450–453. 3. Kim TJ, Lee YY, Kim MJ, et al. Single port access laparoscopic adnexal surgery. J Minim Invasive Gynecol. 2009;16:612–615. 4. Yim GW, Jung YW, Paek J, et al. Transumbilical single-port access versus conventional total laparoscopic hysterectomy: surgical outcomes. Am J Obstet Gynecol. 2010;203:26e1–26e6. 5. Fagotti A, Bottoni C, Vizzielli G, et al. Postoperative pain after conventional laparoscopy and laparoendoscopic single site surgery (LESS) for benign adnexal disease: a randomized trial. Fertil Steril. 2011;96: 255–259e2. 6. Lee YY, Kim TJ, Kim CJ, et al. Single port access laparoscopic adnexal surgery versus conventional laparoscopic adnexal surgery: a comparison of peri-operative outcomes. Eur J Obstet Gynecol Reprod Biol. 2010;151:181–184. 7. Eom JM, Ko JH, Choi JS, Hong JH, Lee JH. A comparative crosssectional study on cosmetic outcomes after single port or conventional laparoscopic surgery. Eur J Obstet Gynecol Reprod Biol. 2013;167: 104–109. 8. Escobar PF, Starks DC, Fader AN, Barber M, Rojas-Espalliat L. Singleport risk-reducing salpingo-oophorectomy with and without hysterectomy: surgical outcomes and learning curve analysis. Gynecol Oncol. 2010;119:43–47. 9. Fagotti A, Fanfani F, Marocco F, et al. Laparoendoscopic single-site surgery for the treatment of benign adnexal diseases: a pilot study. Surg Endosc. 2011;25:1215–1221. 10. Yoon BS, Park H, Seong SJ, Park CT, Jun HS, Kim IH. Single-port versus conventional laparoscopic salpingectomy in tubal pregnancy: a comparison of surgical outcomes. Eur J Obstet Gynecol Reprod Biol. 2011;159:190–193. 11. Paek J, Kim SW, Lee SH, et al. Learning curve and surgical outcome for single-port access total laparoscopic hysterectomy in 100 consecutive cases. Gynecol Obstet Invest. 2011;72:227–233. 12. Song T, Kim TJ, Lee YY, et al. Learning curves for single-site laparoscopic ovarian surgery. J Minim Invasive Gynecol. 2012;19:344–349. 13. Brown J. AAGL advancing minimally invasive gynecology worldwide: statement to the FDA on power morcellation. J Minim Invasive Gynecol. 2014;21:970–971. 14. Kim SK, Lee JH, Lee JR, Suh CS, Kim SH. Laparoendoscopic singlesite myomectomy versus conventional laparoscopic myomectomy: a comparison of surgical outcomes. J Minim Invasive Gynecol. 2014; 21:775–781. 15. Yoon A, Kim TJ, Lee YY, et al. Laparoendoscopic single-site (LESS) myomectomy: characteristics of the appropriate myoma. Eur J Obstet Gynecol Reprod Biol. 2014;175:58–61. 16. Han CM, Lee CL, Su H, Wu PJ, Wang CJ, Yen CF. Single-port laparoscopic myomectomy: initial operative experience and comparative outcome. Arch Gynecol Obstet. 2013;287:295–300. 17. Kim JY, Kim KH, Choi JS, Lee JH. A prospective matched case-control study of laparoendoscopic single-site vs conventional laparoscopic myomectomy. J Minim Invasive Gynecol. 2014;21:1036–1040. 18. Centner V, Massart DL. Optimization in locally weighted regression. Anal Chem. 1998;70:4206–4211. 19. Lee JH, Lee JR, Jee BC, Suh CS, Kim SH. Safety and feasibility of a single-port laparoscopic adnexal surgery during pregnancy. J Minim Invasive Gynecol. 2013;20:864–870. 20. Escobar PF, Starks D, Fader AN, Catenacci M, Falcone T. Laparoendoscopic single-site and natural orifice surgery in gynecology. Fertil Steril. 2010;94:2497–2502. 21. Kadar N, Reich H, Liu CY, Manko GF, Gimpelson R. Incisional hernias after major laparoscopic gynecologic procedures. Am J Obstet Gynecol. 1993;168:1493–1495. 22. Yang B, Xu B, Zeng Q, et al. A specialized course of basic skills training for single-port laparoscopic surgery. Surgery. 2011;149:766–775.
