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Figure. Flow diagram for the systematic review from the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement.

Figure. Flow diagram for the systematic review from the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement.

Table 1. Studies Investigating Outcomes of SILC
Table 1. Studies Investigating Outcomes of SILC
Table 2. Outcomes of SILC
Table 2. Outcomes of SILC
Table 3. Socioeconomic Outcomes of SILC
Table 3. Socioeconomic Outcomes of SILC
Table 4. Intraoperative Outcomes
Table 4. Intraoperative Outcomes
1.
Navarra G, Pozza E, Occhionorelli S, Carcoforo P, Donini I. One-wound laparoscopic cholecystectomy.  Br J Surg. 1997;84(5):6959171771PubMedGoogle ScholarCrossref
2.
Allemann P, Schafer M, Demartines N. Critical appraisal of single port access cholecystectomy.  Br J Surg. 2010;97(10):1476-148020641051PubMedGoogle ScholarCrossref
3.
Aprea G, Coppola Bottazzi E, Guida F, Masone S, Persico G. Laparoendoscopic single site (LESS) versus classic video-laparoscopic cholecystectomy: a randomized prospective study.  J Surg Res. 2011;166(2):e109-e11221227454PubMedGoogle ScholarCrossref
4.
Asakuma M, Hayashi M, Komeda K,  et al.  Impact of single-port cholecystectomy on postoperative pain.  Br J Surg. 2011;98(7):991-99521538340PubMedGoogle ScholarCrossref
5.
Bucher P, Pugin F, Buchs N, Ostermann S, Charara F, Morel P. Single port access laparoscopic cholecystectomy (with video).  World J Surg. 2009;33(5):1015-101919116734PubMedGoogle ScholarCrossref
6.
Carr A, Bhavaraju A, Goza J, Wilson R. Initial experience with single-incision laparoscopic cholecystectomy.  Am Surg. 2010;76(7):703-70720698374PubMedGoogle Scholar
7.
Chang SK, Tay CW, Bicol RA, Lee YY, Madhavan K. A case-control study of single-incision versus standard laparoscopic cholecystectomy.  World J Surg. 2011;35(2):289-29321057790PubMedGoogle ScholarCrossref
8.
Chow A, Purkayastha S, Paraskeva P. Appendicectomy and cholecystectomy using single-incision laparoscopic surgery (SILS): the first UK experience.  Surg Innov. 2009;16(3):211-21719723692PubMedGoogle ScholarCrossref
9.
Cuesta MA, Berends F, Veenhof AA. The “invisible cholecystectomy”: a transumbilical laparoscopic operation without a scar.  Surg Endosc. 2008;22(5):1211-121317943370PubMedGoogle ScholarCrossref
10.
Curcillo PG II, Wu AS, Podolsky ER,  et al.  Single-port-access (SPA) cholecystectomy: a multi-institutional report of the first 297 cases.  Surg Endosc. 2010;24(8):1854-186020135180PubMedGoogle ScholarCrossref
11.
Dominguez G, Durand L, De Rosa J, Danguise E, Arozamena C, Ferraina PA. Retraction and triangulation with neodymium magnetic forceps for single-port laparoscopic cholecystectomy.  Surg Endosc. 2009;23(7):1660-166619415381PubMedGoogle ScholarCrossref
12.
Duron VP, Nicastri GR, Gill PS. Novel technique for a single-incision laparoscopic surgery (SILS) approach to cholecystectomy: single-institution case series.  Surg Endosc. 2011;25(5):1666-167121057963PubMedGoogle ScholarCrossref
13.
Edwards C, Bradshaw A, Ahearne P,  et al.  Single-incision laparoscopic cholecystectomy is feasible: initial experience with 80 cases.  Surg Endosc. 2010;24(9):2241-224720198490PubMedGoogle ScholarCrossref
14.
Elsey JK, Feliciano DV. Initial experience with single-incision laparoscopic cholecystectomy.  J Am Coll Surg. 2010;210(5):620-62620421017PubMedGoogle ScholarCrossref
15.
Erbella J Jr, Bunch GM. Single-incision laparoscopic cholecystectomy: the first 100 outpatients.  Surg Endosc. 2010;24(8):1958-196120112110PubMedGoogle ScholarCrossref
16.
Fronza JS, Linn JG, Nagle AP, Soper NJ. A single institution's experience with single incision cholecystectomy compared to standard laparoscopic cholecystectomy.  Surgery. 2010;148(4):731-73620708764PubMedGoogle ScholarCrossref
17.
Fumagalli U, Verrusio C, Elmore U, Massaron S, Rosati R. Preliminary results of transumbilical single-port laparoscopic cholecystectomy.  Updates Surg. 2010;62(2):105-10920859718PubMedGoogle ScholarCrossref
18.
Han HJ, Choi SB, Park MS,  et al.  Learning curve of single port laparoscopic cholecystectomy determined using the non-linear ordinary least squares method based on a non-linear regression model: an analysis of 150 consecutive patients.  J Hepatobiliary Pancreat Sci. 2011;18(4):510-51521487757PubMedGoogle ScholarCrossref
19.
Hayashi M, Asakuma M, Komeda K, Miyamoto Y, Hirokawa F, Tanigawa N. Effectiveness of a surgical glove port for single port surgery.  World J Surg. 2010;34(10):2487-248920703477PubMedGoogle ScholarCrossref
20.
Hirano Y, Watanabe T, Uchida T,  et al.  Single-incision laparoscopic cholecystectomy: single institution experience and literature review.  World J Gastroenterol. 2010;16(2):270-27420066749PubMedGoogle ScholarCrossref
21.
Hodgett SE, Hernandez JM, Morton CA, Ross SB, Albrink M, Rosemurgy AS. Laparoendoscopic single site (LESS) cholecystectomy.  J Gastrointest Surg. 2009;13(2):188-19219031097PubMedGoogle ScholarCrossref
22.
Hong TH, You YK, Lee KH. Transumbilical single-port laparoscopic cholecystectomy: scarless cholecystectomy.  Surg Endosc. 2009;23(6):1393-139719118436PubMedGoogle ScholarCrossref
23.
Ito M, Asano Y, Horiguchi A,  et al.  Cholecystectomy using single-incision laparoscopic surgery with a new SILS port.  J Hepatobiliary Pancreat Sci. 2010;17(5):688-69120703847PubMedGoogle ScholarCrossref
24.
Khambaty F, Brody F, Vaziri K, Edwards C. Laparoscopic versus single-incision cholecystectomy.  World J Surg. 2011;35(5):967-97221359686PubMedGoogle ScholarCrossref
25.
Kilian M, Raue W, Menenakos C, Wassersleben B, Hartmann J. Transvaginal-hybrid vs single-port-access vs “conventional” laparoscopic cholecystectomy: a prospective observational study.  Langenbecks Arch Surg. 2011;396(5):709-71521384187PubMedGoogle ScholarCrossref
26.
Kravetz AJ, Iddings D, Basson MD, Kia MA. The learning curve with single-port cholecystectomy.  JSLS. 2009;13(3):332-33619793472PubMedGoogle Scholar
27.
Kroh M, El-Hayek K, Rosenblatt S,  et al.  First human surgery with a novel single-port robotic system: cholecystectomy using the da Vinci Single-Site platform.  Surg Endosc216381792011;25(11):3566-3573PubMedGoogle Scholar
28.
Lai EC, Yang GP, Tang CN, Yih PC, Chan OC, Li MK. Prospective randomized comparative study of single incision laparoscopic cholecystectomy versus conventional four-port laparoscopic cholecystectomy.  Am J Surg. 2011;202(3):254-25821871979PubMedGoogle ScholarCrossref
29.
Langwieler TE, Nimmesgern T, Back M. Single-port access in laparoscopic cholecystectomy.  Surg Endosc. 2009;23(5):1138-114119263120PubMedGoogle ScholarCrossref
30.
Lee SK, You YK, Park JH, Kim HJ, Lee KK, Kim DG. Single-port transumbilical laparoscopic cholecystectomy: a preliminary study in 37 patients with gallbladder disease.  J Laparoendosc Adv Surg Tech A. 2009;19(4):495-49919630589PubMedGoogle ScholarCrossref
31.
Lee PC, Lo C, Lai PS,  et al.  Randomized clinical trial of single-incision laparoscopic cholecystectomy versus minilaparoscopic cholecystectomy.  Br J Surg. 2010;97(7):1007-101220632264PubMedGoogle ScholarCrossref
32.
Ma J, Cassera MA, Spaun GO, Hammill CW, Hansen PD, Aliabadi-Wahle S. Randomized controlled trial comparing single-port laparoscopic cholecystectomy and four-port laparoscopic cholecystectomy.  Ann Surg. 2011;254(1):22-2721494123PubMedGoogle ScholarCrossref
33.
MacDonald ER, Alkari B, Ahmed I. “Single-port” laparoscopic cholecystectomy: the Aberdeen technique.  Surg Laparosc Endosc Percutan Tech. 2010;20(1):e7-e920173611PubMedGoogle ScholarCrossref
34.
Marks J, Tacchino R, Roberts K,  et al.  Prospective randomized controlled trial of traditional laparoscopic cholecystectomy versus single-incision laparoscopic cholecystectomy: report of preliminary data.  Am J Surg. 2011;201(3):369-37321367381PubMedGoogle ScholarCrossref
35.
McGregor CG, Sodergren MH, Aslanyan A,  et al.  Evaluating systemic stress response in single port vs multi-port laparoscopic cholecystectomy.  J Gastrointest Surg. 2011;15(4):614-62221308488PubMedGoogle ScholarCrossref
36.
Mutter D, Leroy J, Cahill R, Marescaux J. A simple technical option for single-port cholecystectomy.  Surg Innov. 2008;15(4):332-33319036737PubMedGoogle ScholarCrossref
37.
Palanivelu C, Rajan PS, Rangarajan M, Parthasarathi R, Senthilnathan P, Praveenraj P. Transumbilical flexible endoscopic cholecystectomy in humans: first feasibility study using a hybrid technique.  Endoscopy. 2008;40(5):428-43118459078PubMedGoogle ScholarCrossref
38.
Philipp SR, Miedema BW, Thaler K. Single-incision laparoscopic cholecystectomy using conventional instruments: early experience in comparison with the gold standard.  J Am Coll Surg. 2009;209(5):632-63719854405PubMedGoogle ScholarCrossref
39.
Podolsky ER, Rottman SJ, Curcillo PG II. Single port access (SPA) cholecystectomy: two year follow-up.  JSLS. 2009;13(4):528-53520202394PubMedGoogle ScholarCrossref
40.
Prasad A, Mukherjee KA, Kaul S, Kaur M. Postoperative pain after cholecystectomy: conventional laparoscopy versus single-incision laparoscopic surgery.  J Minim Access Surg. 2011;7(1):24-2721197238PubMedGoogle Scholar
41.
Qiu Z, Sun J, Pu Y, Jiang T, Cao J, Wu W. Learning curve of transumbilical single incision laparoscopic cholecystectomy (SILS): a preliminary study of 80 selected patients with benign gallbladder diseases.  World J Surg. 2011;35(9):2092-210121660626PubMedGoogle ScholarCrossref
42.
Rao PP, Bhagwat SM, Rane A, Rao PP. The feasibility of single port laparoscopic cholecystectomy: a pilot study of 20 cases.  HPB (Oxford). 2008;10(5):336-34018982149PubMedGoogle ScholarCrossref
43.
Rawlings A, Hodgett SE, Matthews BD, Strasberg SM, Quasebarth M, Brunt LM. Single-incision laparoscopic cholecystectomy: initial experience with critical view of safety dissection and routine intraoperative cholangiography.  J Am Coll Surg. 2010;211(1):1-720610242PubMedGoogle ScholarCrossref
44.
Rivas H, Varela E, Scott D. Single-incision laparoscopic cholecystectomy: initial evaluation of a large series of patients.  Surg Endosc. 2010;24(6):1403-141220035355PubMedGoogle ScholarCrossref
45.
Roberts KE, Solomon D, Duffy AJ, Bell RL. Single-incision laparoscopic cholecystectomy: a surgeon's initial experience with 56 consecutive cases and a review of the literature.  J Gastrointest Surg. 2010;14(3):506-51019967564PubMedGoogle ScholarCrossref
46.
Romanelli JR, Roshek TB III, Lynn DC, Earle DB. Single-port laparoscopic cholecystectomy: initial experience.  Surg Endosc. 2010;24(6):1374-137920039073PubMedGoogle ScholarCrossref
47.
Tacchino R, Greco F, Matera D. Single-incision laparoscopic cholecystectomy: surgery without a visible scar.  Surg Endosc. 2009;23(4):896-89918815836PubMedGoogle ScholarCrossref
48.
Tsimoyiannis EC, Tsimogiannis KE, Pappas-Gogos G,  et al.  Different pain scores in single transumbilical incision laparoscopic cholecystectomy versus classic laparoscopic cholecystectomy: a randomized controlled trial.  Surg Endosc. 2010;24(8):1842-184820174950PubMedGoogle ScholarCrossref
49.
Wen KC, Lin KY, Chen Y, Lin YF, Wen KS, Uen YH. Feasibility of single-port laparoscopic cholecystectomy using a homemade laparoscopic port: a clinical report of 50 cases.  Surg Endosc. 2011;25(3):879-88220725743PubMedGoogle ScholarCrossref
50.
Zhu JF, Hu H, Ma YZ, Xu MZ. Totally transumbilical endoscopic cholecystectomy without visible abdominal scar using improved instruments.  Surg Endosc. 2009;23(8):1781-178419067062PubMedGoogle ScholarCrossref
51.
Gangl O, Hofer W, Tomaselli F, Sautner T, Függer R. Single incision laparoscopic cholecystectomy (SILC) versus laparoscopic cholecystectomy (LC): a matched pair analysis.  Langenbecks Arch Surg. 2011;396(6):819-82421695591PubMedGoogle ScholarCrossref
52.
Bignell M, Hindmarsh A, Nageswaran H,  et al.  Assessment of cosmetic outcome after laparoscopic cholecystectomy among women 4 years after laparoscopic cholecystectomy: is there a problem?  Surg Endosc. 2011;25(8):2574-257721424204PubMedGoogle ScholarCrossref
53.
Vander Velpen GC, Shimi SM, Cuschieri A. Outcome after cholecystectomy for symptomatic gall stone disease and effect of surgical access: laparoscopic v open approach.  Gut. 1993;34(10):1448-14518244119PubMedGoogle ScholarCrossref
54.
Strasberg SM, Brunt LM. Rationale and use of the critical view of safety in laparoscopic cholecystectomy.  J Am Coll Surg. 2010;211(1):132-13820610259PubMedGoogle ScholarCrossref
55.
Strasberg SM. Avoidance of biliary injury during laparoscopic cholecystectomy.  J Hepatobiliary Pancreat Surg. 2002;9(5):543-54712541037PubMedGoogle ScholarCrossref
56.
Papagoras D, Kanara M, Argiropoulos-Rakas C, Tsianos G. Single port access laparoscopic cholecystectomy (with video).  World J Surg. 2011;35(1):235-23620556609PubMedGoogle ScholarCrossref
57.
Ciulla A, Romeo G, Genova G, Tomasello G, Agnello G, Cstronovo G. Gallbladder carcinoma late metastases and incisional hernia at umbilical port site after laparoscopic cholecystectomy.  G Chir. 2006;27(5):214-21616857110PubMedGoogle Scholar
58.
Tantia O, Jain M, Khanna S, Sen B. Iatrogenic biliary injury: 13,305 cholecystectomies experienced by a single surgical team over more than 13 years.  Surg Endosc. 2008;22(4):1077-108618210186PubMedGoogle ScholarCrossref
59.
Greaves N, Nicholson J. Single incision laparoscopic surgery in general surgery: a review.  Ann R Coll Surg Engl. 2011;93(6):437-44021929912PubMedGoogle ScholarCrossref
Review
July 2012

Single-Incision Laparoscopic Cholecystectomy: A Systematic Review

Arch Surg. 2012;147(7):657-666. doi:10.1001/archsurg.2012.814
Abstract

Objectives To compare the morbidity, pain, cosmesis, and cost-effectiveness of single-incision laparoscopic cholecystectomy (SILC) with standard laparoscopic cholecystectomy (SLC).

Data Sources Existing literature in MEDLINE through July 31, 2011.

Study Selection We reviewed all studies identified through MEDLINE. References were cross-checked to ensure capture of cited pertinent articles. Case reports and series of less than 4 cases were excluded.

Data Synthesis In total we analyzed 49 studies, including 2336 patients. Seven studies consisted of randomized trials and 11 of case-matched control series (compared with SLC). The technical aspects of SILC were not standardized. Median follow-up time was 4 weeks, although 27 studies (55.1%) reported no follow-up. The overall median complication rate was 7.37% (range, 0-28.6%), and the overall rate of biliary duct complications was 0.39%. Postoperative pain was similar or worse in SILC compared with SLC in 10 of 13 articles reporting pain outcomes (76.9%). Six articles investigating cosmesis after SILC compared outcomes with those of SLC. Three articles demonstrated significantly improved cosmesis after SILC.

Conclusions The perceived benefits of SILC compared with SLC are improved cosmesis and reduced surgical trauma. No definitive evidence suggests that such improvements can be gained by SILC. Complications are more common, may be underestimated owing to the lack of sufficient follow-up, and may be associated with a shift from safe practice.

Surgery remains the mainstay of treatment for biliary disease, and Navarra et al1 first described the laparoscopic removal of a gallbladder through multiple ports in a single periumbilical incision in 1997. Single-incision laparoscopic operations have emerged recently for a range of benign and malignant disease as a putatively less invasive alternative to conventional laparoscopic surgery.

The perceived benefits of single-incision laparoscopic operations compared with conventional laparoscopy include reduced wound pain, improved cosmesis, expedited return to routine activity, and higher patient satisfaction. Although the feasibility of single-incision laparoscopic cholecystectomy (SILC) has largely been established,2 it remains unclear whether SILC represents an improvement in patient care, particularly because a large-scale adoption of such a technique would result in significantly higher costs in the treatment of gallstone disease.

The aim of this systematic review was to critically appraise the available literature evaluating the efficacy and safety of SILC and make comparisons where possible with standard laparoscopic cholecystectomy (SLC). Because the strongest and probably the only arguments for SILC are the purported cosmetic benefit and reduced postoperative pain, we focused on these aspects in addition to examining the safety of the procedure.

Methods

We undertook a MEDLINE literature search using the keywords cholecystectomy, single port, single incision, single site, single access, trans-umbilical, SILS, LESS, R-port, and Tri-port. We included adult human studies reporting outcomes of SILC and limited the search to any English-language article published through July 31, 2011. We excluded articles relating to single-incision procedures in a combination of operations unless data from the cholecystectomies could be extracted. We cross-checked the references in all articles retrieved to ensure capture of cited pertinent articles. A flow diagram of the selection process according to the statement on Preferred Reporting Items for Systematic Reviews and Meta-analyses is presented in the Figure. The primary end point was morbidity as a result of the procedure. Secondary end points included cosmesis, pain, cost, learning curve, and safety with regard to the critical view.

Results

In total, we analyzed 49 studies that met the inclusion criteria with a total of 2336 patients.3-51 These studies included 7 randomized controlled trials3,28,31,32,34,48,51 and 11 case-matched studies comparing outcomes with those of SLC. Most of the studies were case series. Two articles described fewer than 10 patients.20,23 Study size ranged from 4 to 297 patients (Table 1).

Articles were published from 2008 through 2011. Twenty-seven articles (55.1%) recorded no follow-up. The remaining studies described follow-up at a median of 4 postoperative weeks (range, 1 week to 26 months).

Surgical technique and devices varied. Devices described included 3 trocars inserted through a single incision, specially designed multiluminal devices, magnetic forceps, improvised surgical gloves as ports, and robotic devices. Frequently the same article described outcomes using various techniques during the study period, and this heterogeneity made objective outcome comparisons difficult.

Pain

In total, 17 articles investigated postoperative pain.3,4,7,17,24,25,27,28,31,32,34,36,38,40,41,48,51 Pain scores used varied between studies to include the visual analog scale, narcotic requirements, and numerical rating scores (Table 2). The timing of pain scoring also differed between studies, varying from 1 postoperative day and the 2-week follow-up.

Thirteen studies compared postoperative pain in a SILC group with that in an SLC group.3,4,7,24,25,28,31,32,34,38,40,48,51 Seven articles demonstrated no significant difference between cohorts,3,7,25,31,34,40,51 whereas 2 articles described a nonsignificant trend toward increased pain in the single-incision operation.32,38 The article by Lai et al28 demonstrated a similar visual analog scale result at 6 postoperative hours, but on day 7 the SILC group had significantly worse pain than the SLC group. The remaining 3 articles demonstrated significantly reduced postoperative pain in the SILC cohort.4,24,48

Cosmesis

Seven studies investigated patient perception of cosmesis after SILC (Table 2).3,17,28,31,32,34,51 Modes of assessing cosmesis varied between studies. Subjective satisfaction scores were used in 5 articles.28,31,32,34,51 Three studies using a wound satisfaction score found a significantly improved cosmetic appearance for SILC compared with SLC.3,28,31 Another study demonstrated no significant difference in self-assessment score.51

The study by Marks et al34 incorporated a number of validated scores of cosmetic outcome. The 10-point photographic series questionnaire demonstrated significant improvements in wound satisfaction with SILC compared with SLC at 2 postoperative weeks and 3 postoperative months. However, this scoring system could introduce selection bias. The 21-point body-image cosmetic score also showed significant cosmetic improvement with SILC. However, the modified Hollander Incision Attribute Satisfaction Subscale score and the 8- and 12-Item Short Form Health Surveys showed no significant difference.

A study by Ma et al32 used a 10-point score and found no difference between cohorts. The remaining article by Fumagalli et al17 asked patients to subjectively evaluate their satisfaction with the scar. They described 1 patient (4.8%) as unhappy with the cosmetic result.

Cost-effectiveness

Three articles investigated the costs of SILC (Table 3).4,7,19 However, none of these specified a single-incision device. This finding may reflect the fact that a number of studies were performed with financial support from industry. Two studies reporting cost implications investigated an improvised surgical glove method and demonstrated significantly reduced costs compared with SLC.4,19 Both articles described the costs of the improvised surgical glove port as approximately one-quarter of the costs of SLC. In contrast, Chang et al7 used an unspecified SILC port and described costs as greater than SLC costs ($2547 vs $1976). No study performed with the aid of industrial grants declared financial implications.

Learning curve

Eleven studies examined the effect of the learning curve on operating times (Table 3).8,17,18,24,26,32,36,41,46,47 The median operating time across studies was 80.75 (range, 40-186) minutes (Table 4). Among the 16 studies comparing outcomes with those of SLC, operating times were significantly increased in SILC in 9 studies.3,7,16,23,24,32,34,48,51 The remaining 7 studies contained a nonsignificant trend toward longer operating times.

Apart from 1 study,36 a consistently reduced operating time was observed in the authors' institutions after the introduction of SILC (Table 4). A plateau of operating time was achieved after a median 8.5 (range, 3-20) cases. The study by Kravetz et al26 concluded that operating times could be matched to SLC after 5 cases. One study21 demonstrated consistent operating times for the 29 patients undergoing SILC, and another did not show any significant reduction in times.36

Most studies reported operations that were performed by a single surgeon or group of consultant surgeons for whom the specialist area was often minimally invasive surgery. Some articles, however, described the procedure as performed by residents. No study reported the nature of the residents' training.

Safety

The overall median complication rate was 7.37% (range, 0-28.6%). Frequently, studies reported local complications, but these were not defined. The overall rate of bile duct injury was 0.39% (9 of 2336) across all studies (Table 3). Four leaks were secondary to accessory ducts. Because follow-up after single-incision procedures was highly variable and in many cases was not documented, this figure may underestimate this complication in terms of diathermy injuries leading to delayed stricturing of the bile duct.

In articles reporting follow-up (1151 patients), 4 instances of incisional hernia occurred, giving an overall rate of 0.35%. Because length of follow-up varied and was only 2 weeks in some articles, this figure may underestimate true incisional hernia rates.

A clear view or a “critical view of safety” in identifying relevant anatomy in the cholecystectomy triangle is essential to reduce the risk of ductal injury. Thirty-four articles (69.4%) did not explicitly describe the surgeon's perspective of views obtained. The article by Rawlings et al43 investigated specifically the critical view of safety in the SILC of 54 patients. The group used a 3-point grading system, namely, visualization of only 2 ductal structures entering the gallbladder, a clear view of the Calot triangle, and separation of the base of the gallbladder from the cystic plate. All 3 criteria were met in 64%, 2 were met in 24%, 1 was met in 6%, and none were met in 6% of cases. A study by Han et al18 reported outcomes of 150 SILCs performed using the improvised surgicalglove method. They recorded poor views of the Calot triangle in 34% of cases. In their case series of 12 patients using the 3-trocar technique, Tacchino et al47 also described poor views.

Single-incision cholecystectomy was performed without the addition of extra ports (not including transparietal sutures) in 91.25% of operations. Reasons for additional ports included insufficient views, dense adhesions, insertion of a choledochoscope, bleeding, inability of the instruments to reach from the umbilicus, and gallbladder-duodenal fistula. One or more additional ports were required in a median of 8.55% of SILCs (range, 1.3%-66.7%). The rate of open conversion across studies was 0.43% (n = 10).

Ease of surgery was also affected by the indication. Although in all studies cholecystectomy was performed for benign disease, the presentation differed between uncomplicated gallstone disease and acute cholecystitis. Seventeen studies included patients with acute cholecystitis.5-7,12-14,18,24,26,33,35,36,38,44,45,49,51 Patient characteristics, such as body mass index, previous upper abdominal surgery, and local anatomical considerations, added challenges. Many series reported cholecystectomy after bariatric procedures, which will inevitably become increasingly common as the number of these procedures increases.

Twenty-six articles (53.1%) described the routine or selective use of transparietal sutures or other method of retraction to improve visualization of the Calot triangle (Table 2). Such sutures frequently resulted in the intraoperative spillage of bile and reduced the mobilization of the Hartmann pouch during dissection.

Although a source of debate in SLC, the routine use of intraoperative cholangiography has been described as resulting in reduced ductal injuries. Intraoperative cholangiography was attempted selectively or routinely in 15 studies (30.6%). Success in performing intraoperative cholangiography was described in 66.7% to 100% of cases.

Comment

Technical innovation within surgery is laudable, and the progress that results is generally a consequence of the quest to achieve optimum outcomes for patients. However, the advances in surgical technique must improve or at least maintain (and certainly not at the expense of) established safe principles. Perceived improvements in patient satisfaction (with cosmetic outcomes and reduction of pain and surgical trauma) must not increase complications or mandate deviations from safe surgical practice. The aims of this review were to assess morbidity and patient-specific outcomes after SILC and to make comparisons, where possible, with SLC.

Advocates of SILC cite improved cosmesis and reduced surgical trauma (and therefore pain) as reasons for adopting this technique. Despite this, the patient's perspectives of cosmesis and postoperative pain have been poorly investigated and are difficult to assess in an objective fashion. In particular, the advent of the Internet makes this investigation difficult. Demands for the latest procedures are often based on information that is not based on evidence but rather is driven by commercial interests or the biotechnology industry. The most common complaint after SLC is related to the umbilicus. The SILC will inevitably create a bigger incision. Five studies3,17,28,31,51 objectively investigating cosmetic outcomes of SILC compared with SLC and with differing outcomes lead to no firm evidence of this assumption. Only the study by Marks et al34 used a validated scar questionnaire on which to base conclusions.

The issue of cosmesis sidesteps the issue of whether surgeons should suspect patient dissatisfaction with SLC scars and whether this issue can be improved. A study by Bignell et al52 retrospectively investigated patients' satisfaction with cosmesis after SLC in 380 patients using a validated scar questionnaire. Among the 195 patients who responded, 92% were satisfied or extremely satisfied with the cosmetic outcomes after 4 years. This high rate of patient satisfaction with SLC is supported by other series.53 Improvements in cosmesis therefore seem difficult to achieve when high rates of satisfaction exist in established techniques.

The assumption that implementing a single incision reduces postoperative pain is also not largely supported by the results of this review. Thirteen studies have investigated pain and, of these, (76.9%) report similar or worse pain after SILC compared with SLC. Increased pain with the SILC technique may be the result of lengthier operating times and subsequent abdominal wall tension that may improve with the learning curve.

Difficulties arise in interpreting results because heterogeneity exists in surgical technique and the method and timing of pain scoring. The study by McGregor et al35 investigated the acute-phase response in patients undergoing SILC and compared it with the response in patients undergoing SLC. They found no difference in interleukin 6 and C-reactive protein levels between the techniques, indicating that surgical trauma may not be reduced in SILC.

At present, SILC using industry-supplied ports may be more expensive than SLC, although none of the studies in the review provided any objective costs to support this possibility. In contrast, the improvised surgical glove technique was shown to be one-quarter the cost of SLC. Again, cost is difficult to assess when standardization of technique does not exist and series are published beyond the current learning curve.

The large driving force behind SILC might have been commercial marketing; a significant number of the studies in this review are industry funded. This type of activity runs the risk of transforming surgical practice into a commodity offered to patients in various forms based on market research.

In terms of safety, SILC appears to have a greater number of complications compared with SLC, although the learning curve is partly responsible. Operating times are significantly longer in SILC compared with SLC also owing to the learning curve, and times are consistently reduced after a relatively small number of procedures. Operative difficulties may result from the lack of triangulation, pneumoperitoneum leaks, and instrument “clashing.”

The primary concern and source of skepticism for many surgeons considering the place of SILC is the frequent deviation from safe standards and the lack of evidence that such techniques offer any real benefit to the patient. However, the introduction of laparoscopic cholecystectomy nearly 20 years ago saw a rise in the incidence of ductal injury. However, the reaction by the surgical community was not to abandon the laparoscopic procedure. Instead, the American College of Surgeons reviewed causes of this complication and made suggestions regarding safer outcomes. The critical view of safety was defined by Strasberg and Brunt54 to aid dissection in relation to the cystic duct and common bile duct with the aim of preventing ductal injury. Questions remain whether the paradigm of conventional laparoscopic surgery can be further improved by reducing the number of ports used and whether any marginal benefits are cost-effective.

Concerns have been raised whether the hepatocystic triangle truly can be prepared in SILC using transparietal sutures.55,56 Such sutures are advocated by 55.6% of authors routinely or selectively. The routine use and number of additional sutures varied considerably depending on the authors' institution and may contribute to the complications if the critical view of safety is suboptimal. Traction by static sutures does not allow caudolateral movement and may reduce mobile exposure. In unsuspected malignant neoplasms in the gallbladder, the use of sutures may also promote peritoneal dissemination.57

The rates of bile duct injuries and minor or local complications in this review exceed those found in SLC. An overall complication rate of 7.37% and a ductal injury rate of 0.39% were demonstrated; because follow-up is frequently absent or extremely short in studies reporting outcomes, these figures almost certainly underestimate complications, particularly the delayed presentation of ductal injury. The rates of complications such as port-site hernia will also be underestimated, again owing to the lack of long-term results. The complication rates in this review are higher than those reported for SLC, in which ductal complications occur in less than half as many (0.2%) cases and the overall complication rate is less than 1%.58 However, 4 of the 9 reported bile leaks were secondary to accessory ducts. Complications are frequently not correlated with the surgeons' experience, including the authors' rate of complications with SLC, and may contribute to the varying rates observed.

A possible cause of increased rates of umbilical complications may be the creation of circumferential skin flaps to accommodate the subcutaneous ports. This complication occurs with the technique of multiple fascial punctures from a single umbilical skin incision to insert multiple ports. The procedure may result in weakening of the fascia, seroma formation, and late complications, such as port-site hernia. In addition, the trocar type may influence the complication rate; this may become apparent as more studies reporting outcomes using different trocars are reported.

Complications such as wound infection may be increased by the SILC technique. We believe that removing the gallbladder from the umbilical port risks anaerobic microbial seeding in the wound. The use of transparietal sutures increases the rates of intraoperative bile leakage and may contribute to microbial seeding.

Limitations in drawing conclusions from the current published literature in SILC include study heterogeneity. Much variation in technical method, trocar type, instrumentation, transparietal suture use, surgeon experience, and the learning curve is reported. These factors may all contribute to the disparity in reported outcomes.

Conclusions

Although SILC is feasible, the procedure must confer a significant additional benefit to the patient over SLC if we are to advocate its selected or routine use and invest time and energy in its development. Currently, the largest driving forces behind its introduction are from industry and a perceived cosmetic benefit. These cosmetic improvements, however, are not based on evidence, and no evidence suggests that patients are currently dissatisfied with cosmesis after SLC. At present, SILC increases the risk of local complications and ductal injury. To quote a recent article by Greaves and Nicholson, “However, as surgeons we should not advocate for slightly improved cosmetic value over safety.”59(p440)

When the discussion of operative technique takes place, the patient must be informed of the uncertainties of SILC. This conclusion is reflected in the recommendations made by the National Institute for Health and Clinical Excellence (http://www.nice.org.uk) in 2010. Outcomes from systematic reviews rather than market research must guide decisions about surgical procedures if we are to ensure that surgical progress is not dictated by commercial and industrial interests. Technical advances are essential to advance surgical practice, but patients must be protected from procedures and technologies with putative advantages until these can be proven in the context of properly conducted trials.

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Article Information

Correspondence: Thomas C. Hall, MRCS, Department of Hepatobiliary and Pancreatic Surgery, University Hospitals of Leicester, Leicester LE5 4PW, England (tch2@doctors.org.uk).

Accepted for Publication: January 4, 2012.

Author Contributions:Study concept and design: Hall, Dennison, Metcalfe, and Garcea. Acquisition of data: Hall. Analysis and interpretation of data: Hall, Dennison, Bilku, and Garcea. Drafting of the manuscript: Hall, Dennison, Bilku, Metcalfe, and Garcea. Critical revision of the manuscript for important intellectual content: Hall. Statistical analysis: Hall and Metcalfe. Administrative, technical, and material support: Dennison, Metcalfe, and Garcea. Study supervision: Dennison, Metcalfe, and Garcea.

Financial Disclosure: None reported.

References
1.
Navarra G, Pozza E, Occhionorelli S, Carcoforo P, Donini I. One-wound laparoscopic cholecystectomy.  Br J Surg. 1997;84(5):6959171771PubMedGoogle ScholarCrossref
2.
Allemann P, Schafer M, Demartines N. Critical appraisal of single port access cholecystectomy.  Br J Surg. 2010;97(10):1476-148020641051PubMedGoogle ScholarCrossref
3.
Aprea G, Coppola Bottazzi E, Guida F, Masone S, Persico G. Laparoendoscopic single site (LESS) versus classic video-laparoscopic cholecystectomy: a randomized prospective study.  J Surg Res. 2011;166(2):e109-e11221227454PubMedGoogle ScholarCrossref
4.
Asakuma M, Hayashi M, Komeda K,  et al.  Impact of single-port cholecystectomy on postoperative pain.  Br J Surg. 2011;98(7):991-99521538340PubMedGoogle ScholarCrossref
5.
Bucher P, Pugin F, Buchs N, Ostermann S, Charara F, Morel P. Single port access laparoscopic cholecystectomy (with video).  World J Surg. 2009;33(5):1015-101919116734PubMedGoogle ScholarCrossref
6.
Carr A, Bhavaraju A, Goza J, Wilson R. Initial experience with single-incision laparoscopic cholecystectomy.  Am Surg. 2010;76(7):703-70720698374PubMedGoogle Scholar
7.
Chang SK, Tay CW, Bicol RA, Lee YY, Madhavan K. A case-control study of single-incision versus standard laparoscopic cholecystectomy.  World J Surg. 2011;35(2):289-29321057790PubMedGoogle ScholarCrossref
8.
Chow A, Purkayastha S, Paraskeva P. Appendicectomy and cholecystectomy using single-incision laparoscopic surgery (SILS): the first UK experience.  Surg Innov. 2009;16(3):211-21719723692PubMedGoogle ScholarCrossref
9.
Cuesta MA, Berends F, Veenhof AA. The “invisible cholecystectomy”: a transumbilical laparoscopic operation without a scar.  Surg Endosc. 2008;22(5):1211-121317943370PubMedGoogle ScholarCrossref
10.
Curcillo PG II, Wu AS, Podolsky ER,  et al.  Single-port-access (SPA) cholecystectomy: a multi-institutional report of the first 297 cases.  Surg Endosc. 2010;24(8):1854-186020135180PubMedGoogle ScholarCrossref
11.
Dominguez G, Durand L, De Rosa J, Danguise E, Arozamena C, Ferraina PA. Retraction and triangulation with neodymium magnetic forceps for single-port laparoscopic cholecystectomy.  Surg Endosc. 2009;23(7):1660-166619415381PubMedGoogle ScholarCrossref
12.
Duron VP, Nicastri GR, Gill PS. Novel technique for a single-incision laparoscopic surgery (SILS) approach to cholecystectomy: single-institution case series.  Surg Endosc. 2011;25(5):1666-167121057963PubMedGoogle ScholarCrossref
13.
Edwards C, Bradshaw A, Ahearne P,  et al.  Single-incision laparoscopic cholecystectomy is feasible: initial experience with 80 cases.  Surg Endosc. 2010;24(9):2241-224720198490PubMedGoogle ScholarCrossref
14.
Elsey JK, Feliciano DV. Initial experience with single-incision laparoscopic cholecystectomy.  J Am Coll Surg. 2010;210(5):620-62620421017PubMedGoogle ScholarCrossref
15.
Erbella J Jr, Bunch GM. Single-incision laparoscopic cholecystectomy: the first 100 outpatients.  Surg Endosc. 2010;24(8):1958-196120112110PubMedGoogle ScholarCrossref
16.
Fronza JS, Linn JG, Nagle AP, Soper NJ. A single institution's experience with single incision cholecystectomy compared to standard laparoscopic cholecystectomy.  Surgery. 2010;148(4):731-73620708764PubMedGoogle ScholarCrossref
17.
Fumagalli U, Verrusio C, Elmore U, Massaron S, Rosati R. Preliminary results of transumbilical single-port laparoscopic cholecystectomy.  Updates Surg. 2010;62(2):105-10920859718PubMedGoogle ScholarCrossref
18.
Han HJ, Choi SB, Park MS,  et al.  Learning curve of single port laparoscopic cholecystectomy determined using the non-linear ordinary least squares method based on a non-linear regression model: an analysis of 150 consecutive patients.  J Hepatobiliary Pancreat Sci. 2011;18(4):510-51521487757PubMedGoogle ScholarCrossref
19.
Hayashi M, Asakuma M, Komeda K, Miyamoto Y, Hirokawa F, Tanigawa N. Effectiveness of a surgical glove port for single port surgery.  World J Surg. 2010;34(10):2487-248920703477PubMedGoogle ScholarCrossref
20.
Hirano Y, Watanabe T, Uchida T,  et al.  Single-incision laparoscopic cholecystectomy: single institution experience and literature review.  World J Gastroenterol. 2010;16(2):270-27420066749PubMedGoogle ScholarCrossref
21.
Hodgett SE, Hernandez JM, Morton CA, Ross SB, Albrink M, Rosemurgy AS. Laparoendoscopic single site (LESS) cholecystectomy.  J Gastrointest Surg. 2009;13(2):188-19219031097PubMedGoogle ScholarCrossref
22.
Hong TH, You YK, Lee KH. Transumbilical single-port laparoscopic cholecystectomy: scarless cholecystectomy.  Surg Endosc. 2009;23(6):1393-139719118436PubMedGoogle ScholarCrossref
23.
Ito M, Asano Y, Horiguchi A,  et al.  Cholecystectomy using single-incision laparoscopic surgery with a new SILS port.  J Hepatobiliary Pancreat Sci. 2010;17(5):688-69120703847PubMedGoogle ScholarCrossref
24.
Khambaty F, Brody F, Vaziri K, Edwards C. Laparoscopic versus single-incision cholecystectomy.  World J Surg. 2011;35(5):967-97221359686PubMedGoogle ScholarCrossref
25.
Kilian M, Raue W, Menenakos C, Wassersleben B, Hartmann J. Transvaginal-hybrid vs single-port-access vs “conventional” laparoscopic cholecystectomy: a prospective observational study.  Langenbecks Arch Surg. 2011;396(5):709-71521384187PubMedGoogle ScholarCrossref
26.
Kravetz AJ, Iddings D, Basson MD, Kia MA. The learning curve with single-port cholecystectomy.  JSLS. 2009;13(3):332-33619793472PubMedGoogle Scholar
27.
Kroh M, El-Hayek K, Rosenblatt S,  et al.  First human surgery with a novel single-port robotic system: cholecystectomy using the da Vinci Single-Site platform.  Surg Endosc216381792011;25(11):3566-3573PubMedGoogle Scholar
28.
Lai EC, Yang GP, Tang CN, Yih PC, Chan OC, Li MK. Prospective randomized comparative study of single incision laparoscopic cholecystectomy versus conventional four-port laparoscopic cholecystectomy.  Am J Surg. 2011;202(3):254-25821871979PubMedGoogle ScholarCrossref
29.
Langwieler TE, Nimmesgern T, Back M. Single-port access in laparoscopic cholecystectomy.  Surg Endosc. 2009;23(5):1138-114119263120PubMedGoogle ScholarCrossref
30.
Lee SK, You YK, Park JH, Kim HJ, Lee KK, Kim DG. Single-port transumbilical laparoscopic cholecystectomy: a preliminary study in 37 patients with gallbladder disease.  J Laparoendosc Adv Surg Tech A. 2009;19(4):495-49919630589PubMedGoogle ScholarCrossref
31.
Lee PC, Lo C, Lai PS,  et al.  Randomized clinical trial of single-incision laparoscopic cholecystectomy versus minilaparoscopic cholecystectomy.  Br J Surg. 2010;97(7):1007-101220632264PubMedGoogle ScholarCrossref
32.
Ma J, Cassera MA, Spaun GO, Hammill CW, Hansen PD, Aliabadi-Wahle S. Randomized controlled trial comparing single-port laparoscopic cholecystectomy and four-port laparoscopic cholecystectomy.  Ann Surg. 2011;254(1):22-2721494123PubMedGoogle ScholarCrossref
33.
MacDonald ER, Alkari B, Ahmed I. “Single-port” laparoscopic cholecystectomy: the Aberdeen technique.  Surg Laparosc Endosc Percutan Tech. 2010;20(1):e7-e920173611PubMedGoogle ScholarCrossref
34.
Marks J, Tacchino R, Roberts K,  et al.  Prospective randomized controlled trial of traditional laparoscopic cholecystectomy versus single-incision laparoscopic cholecystectomy: report of preliminary data.  Am J Surg. 2011;201(3):369-37321367381PubMedGoogle ScholarCrossref
35.
McGregor CG, Sodergren MH, Aslanyan A,  et al.  Evaluating systemic stress response in single port vs multi-port laparoscopic cholecystectomy.  J Gastrointest Surg. 2011;15(4):614-62221308488PubMedGoogle ScholarCrossref
36.
Mutter D, Leroy J, Cahill R, Marescaux J. A simple technical option for single-port cholecystectomy.  Surg Innov. 2008;15(4):332-33319036737PubMedGoogle ScholarCrossref
37.
Palanivelu C, Rajan PS, Rangarajan M, Parthasarathi R, Senthilnathan P, Praveenraj P. Transumbilical flexible endoscopic cholecystectomy in humans: first feasibility study using a hybrid technique.  Endoscopy. 2008;40(5):428-43118459078PubMedGoogle ScholarCrossref
38.
Philipp SR, Miedema BW, Thaler K. Single-incision laparoscopic cholecystectomy using conventional instruments: early experience in comparison with the gold standard.  J Am Coll Surg. 2009;209(5):632-63719854405PubMedGoogle ScholarCrossref
39.
Podolsky ER, Rottman SJ, Curcillo PG II. Single port access (SPA) cholecystectomy: two year follow-up.  JSLS. 2009;13(4):528-53520202394PubMedGoogle ScholarCrossref
40.
Prasad A, Mukherjee KA, Kaul S, Kaur M. Postoperative pain after cholecystectomy: conventional laparoscopy versus single-incision laparoscopic surgery.  J Minim Access Surg. 2011;7(1):24-2721197238PubMedGoogle Scholar
41.
Qiu Z, Sun J, Pu Y, Jiang T, Cao J, Wu W. Learning curve of transumbilical single incision laparoscopic cholecystectomy (SILS): a preliminary study of 80 selected patients with benign gallbladder diseases.  World J Surg. 2011;35(9):2092-210121660626PubMedGoogle ScholarCrossref
42.
Rao PP, Bhagwat SM, Rane A, Rao PP. The feasibility of single port laparoscopic cholecystectomy: a pilot study of 20 cases.  HPB (Oxford). 2008;10(5):336-34018982149PubMedGoogle ScholarCrossref
43.
Rawlings A, Hodgett SE, Matthews BD, Strasberg SM, Quasebarth M, Brunt LM. Single-incision laparoscopic cholecystectomy: initial experience with critical view of safety dissection and routine intraoperative cholangiography.  J Am Coll Surg. 2010;211(1):1-720610242PubMedGoogle ScholarCrossref
44.
Rivas H, Varela E, Scott D. Single-incision laparoscopic cholecystectomy: initial evaluation of a large series of patients.  Surg Endosc. 2010;24(6):1403-141220035355PubMedGoogle ScholarCrossref
45.
Roberts KE, Solomon D, Duffy AJ, Bell RL. Single-incision laparoscopic cholecystectomy: a surgeon's initial experience with 56 consecutive cases and a review of the literature.  J Gastrointest Surg. 2010;14(3):506-51019967564PubMedGoogle ScholarCrossref
46.
Romanelli JR, Roshek TB III, Lynn DC, Earle DB. Single-port laparoscopic cholecystectomy: initial experience.  Surg Endosc. 2010;24(6):1374-137920039073PubMedGoogle ScholarCrossref
47.
Tacchino R, Greco F, Matera D. Single-incision laparoscopic cholecystectomy: surgery without a visible scar.  Surg Endosc. 2009;23(4):896-89918815836PubMedGoogle ScholarCrossref
48.
Tsimoyiannis EC, Tsimogiannis KE, Pappas-Gogos G,  et al.  Different pain scores in single transumbilical incision laparoscopic cholecystectomy versus classic laparoscopic cholecystectomy: a randomized controlled trial.  Surg Endosc. 2010;24(8):1842-184820174950PubMedGoogle ScholarCrossref
49.
Wen KC, Lin KY, Chen Y, Lin YF, Wen KS, Uen YH. Feasibility of single-port laparoscopic cholecystectomy using a homemade laparoscopic port: a clinical report of 50 cases.  Surg Endosc. 2011;25(3):879-88220725743PubMedGoogle ScholarCrossref
50.
Zhu JF, Hu H, Ma YZ, Xu MZ. Totally transumbilical endoscopic cholecystectomy without visible abdominal scar using improved instruments.  Surg Endosc. 2009;23(8):1781-178419067062PubMedGoogle ScholarCrossref
51.
Gangl O, Hofer W, Tomaselli F, Sautner T, Függer R. Single incision laparoscopic cholecystectomy (SILC) versus laparoscopic cholecystectomy (LC): a matched pair analysis.  Langenbecks Arch Surg. 2011;396(6):819-82421695591PubMedGoogle ScholarCrossref
52.
Bignell M, Hindmarsh A, Nageswaran H,  et al.  Assessment of cosmetic outcome after laparoscopic cholecystectomy among women 4 years after laparoscopic cholecystectomy: is there a problem?  Surg Endosc. 2011;25(8):2574-257721424204PubMedGoogle ScholarCrossref
53.
Vander Velpen GC, Shimi SM, Cuschieri A. Outcome after cholecystectomy for symptomatic gall stone disease and effect of surgical access: laparoscopic v open approach.  Gut. 1993;34(10):1448-14518244119PubMedGoogle ScholarCrossref
54.
Strasberg SM, Brunt LM. Rationale and use of the critical view of safety in laparoscopic cholecystectomy.  J Am Coll Surg. 2010;211(1):132-13820610259PubMedGoogle ScholarCrossref
55.
Strasberg SM. Avoidance of biliary injury during laparoscopic cholecystectomy.  J Hepatobiliary Pancreat Surg. 2002;9(5):543-54712541037PubMedGoogle ScholarCrossref
56.
Papagoras D, Kanara M, Argiropoulos-Rakas C, Tsianos G. Single port access laparoscopic cholecystectomy (with video).  World J Surg. 2011;35(1):235-23620556609PubMedGoogle ScholarCrossref
57.
Ciulla A, Romeo G, Genova G, Tomasello G, Agnello G, Cstronovo G. Gallbladder carcinoma late metastases and incisional hernia at umbilical port site after laparoscopic cholecystectomy.  G Chir. 2006;27(5):214-21616857110PubMedGoogle Scholar
58.
Tantia O, Jain M, Khanna S, Sen B. Iatrogenic biliary injury: 13,305 cholecystectomies experienced by a single surgical team over more than 13 years.  Surg Endosc. 2008;22(4):1077-108618210186PubMedGoogle ScholarCrossref
59.
Greaves N, Nicholson J. Single incision laparoscopic surgery in general surgery: a review.  Ann R Coll Surg Engl. 2011;93(6):437-44021929912PubMedGoogle ScholarCrossref
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