The effect of different single ports on performance in single-incision laparoscopic surgery

Abstract

Aims: In the rapidly advancing world of laparoendoscopic surgery, surgeons are faced with new devices all of which are aimed towards a single access. Various single-access devices are available on the market. Our study aimed to compare the performance of experienced laparoscopic surgeons on validated laparoscopic tasks using five devices within a simulation setting.
Methods: Ten experienced consultant laparoscopic surgeons were recruited after completing a questionnaire and meeting the inclusion criteria of the study. Five different single-access devices were assessed. Each participant performed two validated laparoscopic simulation tasks: peg transfer and pattern cut. All surgeons completed both tasks on all five devices in a randomized order. The performance time and the number of errors and instrument clashes on each task were measured. Statistical analysis was carried out using one-way analysis of variance.
Results: All participants were consultant laparoscopic surgeons with 4–20 years of experience with laparoscopy and fulfilled the selection criteria. One-way analysis of variance revealed no statistically significant differences in performance time (peg transfer, P = 0.306; pattern cut, P = 0.819), number of errors (peg transfer, P = 0.182; pattern cut, P = 0.478) or instrument clashes (peg transfer, P = 0.446; pattern cut, P = 0.061) between the different singe-access devices.
Conclusion: In our study, the laparoscopy experts performed equally well on all five single-access devices within a validated simulation environment. More and larger studies in simulated as well as clinical environments are required to provide further evidence.

Full text

ORIGINAL ARTICLE
The effect of different single ports on performance in
single-incision laparoscopic surgery
Georgios Pafitanis,
1,2,3
Sofronis Loizides
1,4
and Bijendra Patel
1,2
1
Barts Institute of Cancer, Queen Mary University of London, London, UK;
2
Academic Department of Upper GI Surgery, Barts and
The Royal London Hospital, London, UK;
3
Blizard Institute of Cell and Molecular, Barts and the London School of Medicine and
Dentistry, London, UK;
4
Department of Upper GI Surgery, St Peters Hospital, Chertsey, UK
Corresponding author: Dr Georgios Pafitanis, 18 Norfolk Square, W21RS, London, UK. Email: pafitanis@gmail.com
Date accepted for publication: 6 November 2014
Abstract
Aims: In the rapidly advancing world of laparoendoscopic surgery, surgeons are faced with new devices all of which are
aimed towards a single access. Various single-access devices are available on the market. Our study aimed to compare the
performance of experienced laparoscopic surgeons on validated laparoscopic tasks using five devices within a simulation
setting. Methods: Ten experienced consultant laparoscopic surgeons were recruited after completing a questionnaire and
meeting the inclusion criteria of the study. Five different single-access devices were assessed. Each participant performed
two validated laparoscopic simulation tasks: peg transfer and pattern cut. All surgeons completed both tasks on all five
devices in a randomized order. The performance time and the number of errors and instrument clashes on each task were
measured. Statistical analysis was carried out using one-way analysis of variance. Results: All participants were consultant
laparoscopic surgeons with 4–20 years of experience with laparoscopy and fulfilled the selection criteria. One-way analysis
of variance revealed no statistically significant differences in performance time (peg transfer, P= 0.306; pattern cut,
P= 0.819), number of errors (peg transfer, P= 0.182; pattern cut, P= 0.478) or instrument clashes (peg transfer, P= 0.446;
pattern cut, P= 0.061) between the different singe-access devices. Conclusion: In our study, the laparoscopy experts
performed equally well on all five single-access devices within a validated simulation environment. More and larger studies
in simulated as well as clinical environments are required to provide further evidence.
Keywords: Single-incision laparoscopic surgery; laparoendoscopic single-site surgery; instruments; single port; laparoendoscopy
Introduction
Laparoendoscopic single-site surgery (LESS) is one of the
latest innovations in minimally invasive surgery and there
has been an increased uptake of the technique by many
surgical specialities.
1
Randomized controlled trials are now
emerging, which show that LESS is as safe as conventional
laparoscopic surgery.
2
Furthermore, LESS may confer
advantages such as better cosmetic results and less post-
operative pain.
3,4
LESS is technically demanding. The challenge is attributed
to the coaxial arrangement of the instruments, instrument
crowding, loss of depth perception and the loss of triangu-
lation. The technical skills and manual dexterity required
are different from standard laparoscopic surgery and LESS
has a steeper learning curve. Even experienced LESS sur-
geons do not perform as well in LESS simulation tasks
compared with tasks using conventional laparoscopic
access.
5
Several manufacturing companies have shown great interest
in the technological advancement of LESS. Different single-
access devices with ergonomic characteristics designed to
overcome the inherent limitations of LESS have been devel-
oped. Single-access devices combine a camera port and clas-
sically two or three working ports (although some devices
support a larger number of working ports). The facial inci-
sion required, fixation mechanism and other ergonomic
characteristics of single-access devices are summarized in
Table 1.
Another development has been that of articulating and pre-
bent instruments, which permits intra-corporeal triangula-
tion despite crowding in the single-access port.
7
We have found only one study comparing different com-
mercially available single-access devices in laparoscopic
simulation tasks.
8
Our study aimed to compare the perfor-
mance of experienced laparoscopic surgeons in validated
laparoscopic simulation tasks using four commercially
Surgical Simulation
JOURNAL OF
Journal of Surgical Simulation (2015) 2, 6–11
DOI: 10.1102/2051-7726.2015.0002
ß2015 The Authors. Published by Journal of Surgical Simulation. This work is licensed under a Creative Commons Attribution-
NonCommercial 4.0 International License.

available single-access devices as well as a home-made
single-access port.
Materials and methods
Participants and Study Design
Entry criteria for the study included (1) having participated
in more than 100 conventional laparoscopic procedures as
the main operator, (2) being non-proficient in LESS defined
as less than ten procedures as the main operator, and (3)
having achieved the Fundamentals of Laparoscopic Surgery
(FLS) expert-derived performance level
9
on a pre-test car-
ried out during recruitment. Before recruitment, all sur-
geons filled in a questionnaire, describing their previous
laparoscopic experience.
The surgeons were assessed on a basic (peg transfer, Fig. 1)
and an intermediate (pattern cutting, Fig. 2) laparoscopic
task on all five single-access devices. These validated tasks
have been described in the FLS course
9
and have been used
extensively in laparoscopic simulation. Performance on both
FLS tasks was assessed by performance time, number of
errors (as defined in the FLS Technical Skills Proficiency-
Based Training Curriculum
9
) and number of instrument
clashes. Each surgeon undertook the tasks in the single-
access devices in a randomized order (computer-generated
randomization).
Simulation Setup and Equipment
Experiments were conducted on a LESS box trainer (Fig. 3)
in a laparoscopic simulation suite. The surgeons used
conventional straight laparoscopic instruments to perform
the tasks. Five different single-access devices were utilized:
four commercially available devices and a home-made
multi-access port (Table 1 and Figs 4–8).
6
Statistical Analysis
The data were tabulated and analysed in SPSS version 14.0
(Statistical Package for the Social Sciences). Parametric
data analysis was carried out using one-way analysis of var-
iance (ANOVA). Tukey’s multiple comparison test was used
to compare all possible pairs of single-access devices.
The results are presented as means standard error
Table 1 Multi-channel ports
Tri-Port or R Port SILS (single incision
laparoscopic sur-
gery) multiple access
port
GelPort laparoscopic
system
SSL (single-sited
laparoscopic) port
Multiple standard
trocar port
Manufacturer Advanced Surgical
Concepts, Bray,
Ireland
Covidien, Norwalk,
CT
Applied Medical,
Rancho Santa
Margarita, CA
Ethicon Endo-Surgery Home-made trans-
umbilical port
6
Lumen sizes 1 12 mm port and
25 mm ports
3 ports from 5 to 12
mm
Gel Seal Cap, variable
ports
25 mm seals and
115 mm seal
3, 4 or more 
5–12 mm trocars
Fixation
mechanism
Self-expanding ring
sheath, inner/outer
elastic ring
Red-cell shaped elas-
tic polymer
Alexis retractor,
inner/outer elastic
ring
Fixed length retractors
consist of two flexible
rings with silicon sleeve
connection
Alexis retractor or
friction
Facial incision
required
1.5–2.5 cm 1.5–2 cm Variable (1.5–10 cm) 2 cm Variable (depending
on the size of the
Alexis retractor)
Range of
abdominal
thickness
Up to 10 cm Up to 4 cm Up to 6 cm Fixed length retractors:
4 cm and 4–7 cm thick-
ness of abdominal wall
Depends on the
length of the Alexis
Retractor used
Figure 1 Basic laparoscopic task: peg transfer.
G. Pafitanis et al.Single-access devices for laparoscopic surgery 7

of the mean (SEM) with P50.05 considered statistically
significant.
Results
Ten consultant laparoscopic surgeons, one left handed and
nine right handed (four general surgeons, two colorectal
surgeons, two hepatobiliary surgeons and two gynaecolo-
gists) met the inclusion criteria of the study. Their mean
experience with conventional laparoscopic surgery was
11.8 5.2 years. In terms of LESS, the average number of
procedures performed by the participants was 6 3.
The performance times for each of the simulation tasks are
shown in Table 2. These results were not significantly dif-
ferent between the different single-access devices (ANOVA
test: peg transfer, P= 0.306; cut pattern, P= 0.819). Tukey’s
multiple comparison test did not demonstrate any statistical
significance when comparing pairs.
In order to assess performance precision, we looked at the
number of errors performed and instrument clashes. The
number of errors performed for peg transfer and pattern
cut are presented in Table 2. One-way ANOVA showed no
significant difference between devices with regard to the
mean number of errors for peg transfer (P= 0.182) or pat-
tern cut (P= 0.478). There were no significant differences
when comparing in pairs (Tukey’s multiple comparison
test).
We then looked at the number of instrument clashes
(Table 2). There was no significant difference in the mean
number of clashes for peg transfer (P= 0.947) or pattern cut
(P= 0.061) between devices.
Discussion
LESS has potential advantages over conventional laparo-
scopy including improved cosmesis, less pain and higher
patient satisfaction.
4
As with any surgical innovation, LESS
has been fraught with problems. It is time consuming and
requires advanced laparoendoscopic technical skills, which
are difficult to acquire. As a result, simulation may be a
useful stepping stone in the development of better under-
standing of the technical difficulties, the devices and smart
instruments, as well as improvements in LESS skills before
clinical application.
The initial steps of LESS involved multiple ports placed
through separate facial incisions but one single skin incision
at the umbilicus. Manufacturing companies have since
developed different types of single-access devices with cer-
tain ergonomic characteristics designed to facilitate opera-
tive performance. The cost of LESS single-access devices and
smart instruments is a significant issue that might decelerate
its uptake.
Surgeons keen on LESS have chosen to use a home-made
single-access multi-port setup.
10
In our study, the home-made
Figure 3 Box trainer.
Figure 2 Intermediate laparoscopic task: pattern cutting.
8G. Pafitanis et al.Single-access devices for laparoscopic surgery

setup did not perform inferiorly to the commercially available
ports. However, clinically, the facial holes can sometimes
coalesce and cause gas leakage. Studying these ergonomic
properties of the devices was beyond the scope of our
study. A study from Xie et al.
11
demonstrated mechanical
differences between ports, showing that the multi-port devices
offer superior maneuverability.
When the instruments and telescope are inserted through
the single-access device into the abdominal cavity, there is a
natural tendency for clashing and loss of triangulation. This
has become known as sword fighting or the chopsticks
effect. Furthermore, the rigid core body of some single-
access devices affects the movement of the ancillary instru-
ment when the primary instrument is moving. As we have
seen, the commercially available single-access devices differ
in lumen size, the distance between lumens, the rigidity of
their core material and fixation mechanisms (Table 1). We
hypothesized that these differences might affect operative
performance and attempted to demonstrate this with the
peg transfer and pattern cut tasks.
Peg transfer is a bimanual task, which tests the movement
of both the primary and ancillary instruments. Similar
opposite direction bimanual skills are necessary when
Figure 6 SILS port.
Figure 8 Multi-standard trocar port.
Figure 5 SSL port.
Figure 4 Tri-port or R port. Figure 7 GelPort laparoscopic system.
G. Pafitanis et al.Single-access devices for laparoscopic surgery 9

performing laparoscopic suturing and when trying to
strengthen an intra-corporeal knot. Our results demon-
strated no significant difference when comparing all five
single-access devices.
The pattern cut task requires a different technique. It is best
performed when the instruments are used in a combination
of crossing and non-crossing movements (the chopstick
technique), as described in robotic LESS by Rohan et al.
12
We observed some of the surgeons applying these simple
principles in order to overcome the difficulties due to loss of
triangulation. Our study again demonstrated that the type of
single-access device does not affect performance of this task.
However, the technical aspects of ports have certain char-
acteristics that make the decision making easier. The cost of
each port is approximately the same in the region of £200;
however, the cost can vary depending on the contract
between the hospital and the manufacturing company.
The GelPort allows extraction of large specimens through
the incision due to the Alexis retractor used for its intro-
duction. The SILS port’s soft material and the GelPort cap
allow the use of different sized instruments (larger than
5 mm) through the multi-trocar ports.
Our study has several limitations. First, the sample size was
small, and that reflects the difficulty of recruiting busy laparo-
scopic surgeons to perform time-consuming simulation tasks.
Second, the performance of the surgeons in advanced laparo-
scopic simulation tasks such as intra-corporeal suturing could
have a major influence on our study but this was not
explored due to time constraints. It is unclear if performance
with simulated single-port laparoscopic tasks is reflected in
clinical practice of single-incision laparoscopic surgery as
already shown with basic laparoscopy. Studies to validate
these aspects are required. Third, it would be interesting to
assess the performance of surgeons with articulating or pre-
bent instruments in combination with different single-access
devices. These instruments allow for pseudo-triangulation to
occur intra-corporeally and can be passed through some of
the single-access devices, which have a very low profile inside
and outside the abdominal wall.
Conclusion
Simulation room training is helpful in understanding the
devices, each with its inherent advantages and disadvan-
tages, and improving LESS skills. We have shown that sur-
geons perform similarly in basic and intermediate validated
laparoscopic simulation tasks when using different single-
access devices. Furthermore, we have shown that a home-
made single-access multi-port setup is not inferior to the
commercial devices currently available. Different ports
maintain advantages according to their ergonomics, which
affects the decision on which device is the best for which
operation.
Further randomized evaluation of the devices in combina-
tion with smart instruments is required both in simulation
and clinical environments. Currently, pre-operative vari-
ables, the surgeon’s preference, as well as institutional
guidelines are likely to determine device selection.
Note
Fundamentals of Laparoscopic Surgery (TM) (FLS) Program
is owned by the Society of American Gastrointestinal and
Endoscopic Surgeons (SAGES) and American College of
Surgeons (ACS). This study is not connected to or approved
by SAGES, ACS or FLS.
Conflict of interest
No conflicts of interest have been declared.
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Table 2 Performance times, errors and clashes of instruments
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value
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(s SEM)
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