The learning curve of single-port laparoscopic appendectomy performed by emergent operation
Kim and Lee World Journal of Emergency Surgery
The learning curve of single-port laparoscopic appendectomy performed by emergent operation
YongHun Kim 1
WooSurng Lee 0
0 Department of Thoracic and Cardiovascular Surgery, School of Medicine, Konkuk University, Konkuk University Chungju Hospital , 82, Gugwon-daero, Chungju-si, Chungbuk , Republic of Korea
1 Department of Surgery, School of Medicine, Konkuk University, Konkuk University Chungju Hospital , 82, Gugwon-daero, Chungju-si, Chungbuk , Republic of Korea
Background: Single-port laparoscopic appendectomy (SPLA) has the advantage of minimizing abdominal incision scars with patient satisfaction. However, it has the following disadvantages: it provides a narrower surgical field than conventional laparoscopic appendectomy, which requires a considerably longer operative time to achieve surgical skills. This study was conducted to evaluate the learning curve for SPLA. Methods: This study included a total of 120 patients with acute abdomen who visited our emergency department and were diagnosed with acute appendicitis between March 2013 and February 2015. They underwent SPLA by a single surgeon. Patients were divided into 4 groups of 30 patients each according to operation dates. Operative time, time to resume oral intake, length of hospital stay, and postoperative complications were analyzed. Results: The mean operative time was 59.9 ± 19.9 min. It was shortened after completion of 30 operations and remained unchanged until it was further shortened after completion of 90 operations. There was no significant difference in time to resumption of oral intake or length of hospital stay between the 4 groups. Postoperative complications occurred in 18 patients, but the frequency of the complications was not significantly different between the 4 groups. Conclusions: The results of this study suggest that surgeons can achieve surgical skills for SPLA after completion of 30 operations and more experienced surgical skills by SPLA successfully after completion of 90 operations.
Learning curve; Laparoscopy; Appendectomy; Emergencies
Laparoscopic appendectomy is minimally invasive
compared to conventional open appendectomy and has the
advantages of decreased postoperative pain, shortened
hospital stay, fewer postoperative complications, and
better cosmesis. It has replaced conventional open
appendectomy in the treatment of acute appendicitis [
Therefore, this laparoscopic appendectomy is currently
the gold standard operation for acute appendicitis and
provides similar surgical outcomes as conventional open
appendectomy, even in cases of complicated appendicitis
. Recently, advances in laparoscopic instruments and
optical systems enabled surgeons to perform
intraabdominal operation through a single incision around
the umbilicus; in particular, single-port laparoscopic
appendectomy (SPLA), which minimizes visible scars in
the abdominal wall, satisfies patients [
]. In addition,
previous randomized controlled studies reported that
SPLA has surgical outcomes similar to those of
threeport laparoscopic appendectomy (TPLA) [
However, since SPLA has the disadvantages of limited
surgical field and difficult access to the operation site through
a small incision compared to TPLA, it requires more
experience with surgical cases and more skills than TPLA,
especially in emergency cases. For this reason, to achieve
surgical outcomes similar to those of TPLA, SPLA
demands additional training programs. Recent preliminary
studies have not yet completely elucidate the learning
curve of SPLA [
]. Thus, the aims of this study were
to analyze the learning curve of SPLA over a longer
period and to assess its surgical safety and feasibility.
This study included a total of 122 patients with acute
abdomen who visited our emergency department and were
diagnosed with acute appendicitis between March 2013
and February 2015. They underwent SPLA. To make a
definite diagnosis of acute appendicitis, all patients were
evaluated using a comprehensive history taking, physical
examination, laboratory findings, and abdominal
computed tomography with contrast enhancement. Each
patient gave informed consent to SPLA. Two patients had
undergone right hemicolectomy for peritonitis with severe
cecal inflammation and diverticular perforation, who were
excluded from the study. All operations were performed
by a single surgeon in the same surgical team who had
experience with more than 500 TPLA cases and more than
500 conventional open appendectomy cases. Patients were
consecutively assigned to 4 groups of 30 patients each:
group A (the first 30 patients), group B (the second 30
patients), group C (the third 30 patients), and group D (the
fourth 30 patients). Clinical data on age, gender, body
mass index (BMI), severity of appendicitis, and previous
history of abdominal surgery was collected and analyzed
with regard to operative time, postoperative
complications, length of hospital stay, time to resume oral intake,
and conversion rate.
SPLA was performed under general anesthesia. The
patent lay on the operating table in the supine position, with
both arms lying outside. Both the surgeon and assistant
stood on the patient’s left side. After a 2-cm mid-line
linear incision was made just above the umbilicus, the
abdominal wall was opened using the Hassan technique.
Once proper umbilical access has been obtained, a Glove
Port (Nelis, Seoul, Korea) was positioned and secured
within the incision, providing both 360° wound protection
and circumferential atraumatic retraction.
Pneumoperitoneum was maintained at 10–12 mm Hg using CO2. SPLA
was conducted using a 5-mm Flexible EndoEYE
laparoscope (Olympus Surgical & Industrial America Inc, Center
Valley, PA, USA) and a 5-mm HiQ™ Curved Instrument
(Olympus Surgical & Industrial America Inc, Center
Valley, PA, USA). The appendix was grasped and pulled with
a 5-mm HiQ™ Curved Instrument immediately on its tip,
if visible, or starting from its base or proximal third and
gradually mobilizing the entire body of the appendix.
When the appendix was stuck by surrounding dense and
thick inflammatory adhesions, the use of a blunt suction
device could be extremely safe and useful for creating a
plane for dissection and mobilization from the
surrounding inflamed viscera and tissues. Once the appendix was
fully mobilized and its base on the cecum was identified,
the mesentery was carefully dissected and coagulated
using a Harmonic scalpel (Ethicon, Blue Ash, OH, USA).
Once the base of the appendix on the cecum was reached
and the mesenteric tissues were fully cleansed, the
appendix base was ready to be knotted using a Surgitie™ loop
(Covidien, Mansfield, MA, USA). Finally, after cutting the
appendix, the specimen was retrieved under direct vision
and extracted through the umbilical glove port. The
operation was terminated with aspiration and eventual
cautious lavage, especially in the right iliac fossa and Douglas
pouch, checking hemostasis on the mesentery and good
closure of the appendiceal stump (Fig. 1).
Data analysis was performed using MedCalc for Windows
version 12.3.0 (MedCalc Software, Ostend, Belgium). In
statistical testing, a two-sided P value of >0.05 was
considered statistically significant. Continuous variables are
expressed as mean ± standard deviation. Categorical
variables are presented as frequency and percentage. In
univariate analysis, Fisher’s exact test and one-way analysis of
variance were used as appropriate for group comparisons.
Then, multivariate analysis was conducted by fitting
multiple linear regression models to identify important
predictors of operative time.
The mean age of the patients was 45.1 ± 16.1 years (range,
19.0–87.0 years), and there were 67 males and 53 females.
The mean BMI was 23.38 ± 3.20 (range, 17.0–34.8). Of the
120 patients, 16 had a history of abdominal surgery: 1 had
cholecystectomy, 9 had cesarean section, 3 had
myomectomy, and 3 had tubal ligation. There was no significant
difference in age, gender, BMI, or history of abdominal
surgery between the 4 groups (Table 1). The types of
appendicitis classified according to severity were as
follows: the suppurative (n = 83), gangrenous (n = 24), and
perforated (n = 13) types. The appendices were
categorized according to their location as follows: the retrocecal
(n = 18), subcecal/pelvic (n = 76), and retroileal (n = 26)
types. The mean operation time was 59.9 ± 19.9 min, and
there was no intra-abdominal injury or massive bleeding
during operation. Of the 120 patients, 4 required
additional port insertion, all of whom belonged to group A.
There were no patients who required conversion to open
appendectomy. The mean time to resume oral intake was
1.5 ± 0.7 days, but it was not significantly different
between the 4 groups (P = 0.418) Postoperative
complications occurred in 18 patients, and most of them were
wound complications (n = 11, 9.1 %). There were four
patients (3.3 %) with intra-abdominal inflammation which
was resolved by antibiotics therapy, without percutaneous
drainage. Postoperative ileus occurred in three patients
(2.5 %), which was improved by conservative treatment.
There was no significant difference in postoperative
complications between the 4 groups (p = 0.853) (Table 1).
Mean operative times were 67.0 ± 23.9 min in group A,
61.7 ± 23.9 min in group B, 60.4 ± 17.5 min in group C,
and 50.6 ± 16.8 min in group D. Mean operative times
were longest in group A and shortest in group D.
Oneway analysis of variance (ANOVA) showed significant
correlations between groups A and D, and between groups B
and C (P = 0.012). The mean operative time was shortened
after completion of 30 operations and remained
unchanged until it was further shortened after completion of
90 operations (Fig. 2). In multiple linear regression
analysis, the severity of appendicitis was significantly
associated with operative time; however, history of
abdominal surgery, location of the appendix, or BMI was not
significantly associated with operative time (Table 2).
Single-puncture tubal ligation via a laparoscopic
singleopening approach was first introduced by Wheeless in
]. Thereafter, this approach has been employed
in the treatment of complicated gynecological diseases
and applied for appendectomy, placement of peritoneal
dialysis catheters, and resection of intra-abdominal cysts
]. Despite such applications in various clinical
conditions, single-port laparoscopic surgery (SPLS) has
not yet been widely performed in real-world practice.
Previous history of AS
Operation time (minutes)
Additional port insertion
Time to ROI (days)
45.1 ± 16.1
23.38 ± 3.2
59.9 ± 19.9
1.5 ± 0.7
5.1 ± 2.5
43.8 ± 17.3
23.58 ± 3.3
67.0 ± 23.9
1.5 ± 0.8
5.3 ± 2.7
44.9 ± 10.8
23.02 ± 3.4
61.7 ± 17.9
1.6 ± 0.8
5.2 ± 2.3
44.6 ± 15.2
23.63 ± 3.1
60.4 ± 17.5
1.5 ± 0.6
4.9 ± 1.9
47.1 ± 17.8
23.30 ± 2.9
50.6 ± 16.8
1.6 ± 0.8
4.8 ± 2.0
Abbreviations: M/F male/female, BMI body mass index, AS abdominal surgery, ROI resumption of oral intake
The reasons for this may be the limitations of SPLS to
clinical indications and the steep learning curve to
overcome. A major problem is difficulty in manipulating the
laparoscope and the instruments introduced through a
single port because surgeons should avoid extra- and
intracorporeal conflict between the laparoscope and the
instruments. Such drawbacks frequently lead to the loss
of triangulation and difficult instrumentation during
SPLS, unlike conventional multiport laparoscopic
surgery. SPLS requires the surgeon and the assistant to
maintain a poor ergonomic position different from that
in conventional laparoscopic surgery. SPLS may be more
difficult to perform than conventional laparoscopic
surgery, prolong operative time, require a steep learning
curve, and have low feasibility and safety [
addressing these issues, many improved devices have
been used in real-world practice: longer laparoscopes
(45 cm in length), laparoscopes with various angles,
improved port systems, such as Home-made Glove port,
SILS™ Port (Covidien Inc, Norwalk, CT, USA), Uni-X™,
AirSeal (SurgiQuest, Orange, CT, USA), Glove port
(Nelis, Seoul, South Korea), and laparoscopic
instruments specifically designed for SPLS, such as
Roticulator™ (Covidien Inc, Norwalk, CT, USA), HiQ LS™
Curved instrument (Olympus Surgical & Industrial
America Inc, Center Valley, PA, USA) [
such advances in laparoscopes and instruments,
surgeons should have a substantial learning curve to
Recently, SPLA has been extensively performed
because of the superior cosmesis with no visible scarring
]. Most of the previous studies have reported that the
clinical outcomes of SPLA are the same as those of
]. Meanwhile, some studies have reported
that SPLA requires a longer operative time and a
substantial learning curve . Liao et al. [
] analyzed 30
cases of non-complicated appendicitis undergoing SPLA
and documented that the operative time for SPLA was
shortened after experience with 10 cases of SPLA, which
became the same as that for TPLA. Validad et al. [
investigated 65 pediatric cases of acute appendicitis
undergoing SPLA and showed that the operative time for
SPLA was equal to that for TPLA, regardless of board
certification. These studies may have some limitations to
interpret their results in that they excluded cases of
complicated appendicitis. However, our study analyzed
120 cases of acute appendicitis which included cases of
complicated appendicitis, so that it has clinical
implications in such aspects. Moreover, since our study
included only SPLA cases during the study period, with
exclusion of TPLA cases, we avoided selection bias and
obtained more general data on the learning curve for
SPLA. The learning curve for SPLA can be assessed by
various parameters, such as blood loss, complication
rates, conversion rates, operative time, and length of
hospital stay, of which operative time and length of
hospital stay are more important [
]. In this study, the
operative time for SPLA was shortened after completion
of 30 SPLA cases, remained unchanged, and was further
shortened significantly after completion of 90 SPLA
cases. Since previous studies on the learning curve for
SPLA had a relatively small sample size (n = 20–50), they
may have some limitations to generalize their results
]. Pan et al. [
] divided 180 consecutive
singleincision laparoscopic cholecystectomies into 9 groups
according to operation dates, and each group included
20 patients operated on consecutively in each time
period. They also reported that the operative time was
significantly longer in group 1 than in the other groups.
By the multiple linear regression model: n = 120, residual standard error = 18.6, R2 = 0.126, overall F test statistic = 4.448, P = 0.001 (df = 5, 114)
Abbreviation: BMI body mass index
Lee et al. [
] divided 160 cases of myoma uteri
requiring single-port laparoscopic myomectomy into 4 groups
according to operation dates and reported that the
operative time declined significantly in the last 3 groups
compared to the first group. Our results on the
progressive decrease in the operative time for SPLA can provide
useful information on a general learning curve for SPLA.
Further studies are needed to confirm our results.
In this study, the learning curve for SPLA showed no
significant changes in the length of hospital stay between
the 4 groups, which is similar to the results of previous
8, 22, 23
] Additionally, there was no significant
difference in the occurrence of postoperative
complications between the 4 groups, which is similar to the
results of previous studies [
]. In TPLA, the
complication rates have been shown to decreases to
<10 % with the mastery of the TPLA technique [
In this study, the complication rate of SPLA turned out
to be 15 %, mainly including wound complications such
as seroma (n = 9), which may have attributed to longer
umbilical incisions and a larger proportion of cases of
complicated appendicitis. The complication rates of
SPLA was acceptable with the exclusion of seroma (9/
120, 7.5 %).
There have been only a few studies on clinical
predictors associated with the operative time for SPLA. Liao et
] have documented that operative time for SPLA is
related to the severity of appendicitis, BMI > 21 kg/m2,
and use of endoloops. Lee et al. [
] have shown that
the operative time for SPLA is not associated with
leukocyte count or duration of symptoms; however, it is
associated with BMI and pathology of the appendix. In
this study, the operative time for SPLA was associated
with the severity of appendicitis, but not with BMI or
the location of the appendix. However, BMI seems more
likely to be a significant factor that can affect the
operation time. In our study, it was found that there was a
less reduction in the operative time in the obese and
extremely obese patients compared to normal weight
patients, but it was not so in underweight patients (Fig. 3),
suggesting that BMI may not be significantly associated
with operative time. Based on these results, it is
conceivable that the severity of appendicitis may affect the
operative time for SPLA. Another considerable limitation
of SPLA is related to costs. The increased costs of SPLA
compared to TPLA are still a considerable disadvantage
that limits the use of SPLA [
]. Di Saverio et al. 
analyzed 45 cases of single-incision laparoscopic
appendectomy using a self-made surgical-glove port and
showed that the postoperative results from their surgical
method were comparable to those from conventional
single-incision laparoscopic appendectomy. They
suggested that their surgical-glove port, single-incision
laparoscopic appendectomy could be considered as a
cost-effective alternative to conventional SPLA using
commercially available devices.
This study has a limitation because all the SPLA cases
were performed by a single surgeon in the same surgical
team. Further studies are needed to achieve a general
learning curve for SPLA.
The results of this study suggest that equipment conflict,
difficulty in manipulating the laparoscope and the
laparoscopic instruments through a small umbilical
incision, and limited surgical field may hamper the clinical
application of SPLA, but that the surgical outcome can
be the same as that of TPLA. Even surgeons proficient
in TPLA will need a substantial learning curve to safely
perform the SPLA technique.
BMI, body mass index; SPLA, single-port laparoscopic appendectomy; SPLS,
single-port laparoscopic surgery; TPLA, three-port laparoscopic
This paper was supported by Konkuk University in 2016.
Availability of data and materials
The data supporting the conclusions of this study are included in the article.
YHK and WSL drafted the manuscript, searched the literature, interpreted
findings, and prepared for manuscript writing/editing and submission of the
manuscript. WSL and YHK critically reviewed the manuscript. All authors have
read and approved the final manuscript submission.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Not sought for and not necessary as this is a retrospective observational
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