Meta-analysis of single-incision versus three-port laparoscopic appendectomy comparing operation time and postoperative pain

Abstract

Background:

Unresolved debates persist regarding operative time and postoperative pain when comparing single-incision laparoscopic appendectomy (SILA) with three-port conventional laparoscopic appendectomy (CLA) for acute appendicitis. To address these issues, we conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing the clinical outcomes of SILA and CLA.

Methods:

An electronic search was performed using PubMed, Embase and the Cochrane Central Register of Controlled Trials through January 2025. The primary outcomes were operative time and postoperative pain, while secondary outcomes included the incidence of postoperative complications, additional trocar requirements, open conversion rate, and cosmetic satisfaction. A meta-regression was conducted to assess the relationship between surgical outcomes and the era in which the surgery was performed.

Results:

After excluding four RCTs because of a high risk of bias in the randomization process, a total of 21 RCTs encompassing 2454 patients were included. The pooled analysis showed that SILA required an average of 3.80 min longer than CLA (mean difference [MD] = 3.80 min, 95% confidence interval [CI]: −0.25 to 7.85; P = 0.07). However, meta-regression of studies arranged by initiation year revealed a significant trend toward a decreased MD with more recent surgeries (P = 0.003). Although the CLA group required fewer additional analgesics (standardized mean difference [SMD] = 0.24, 95% CI: 0.10 to 0.38, P < 0.01), no significant differences were found in pain scores at 12 h (MD = −0.04, 95% CI: −0.72 to 0.63, P = 0.91) or 24 h (MD = 0.08, 95% CI: −0.30 to 0.46, P = 0.67). Furthermore, while postoperative complications and open conversion rates were similar between groups, the SILA group reported higher cosmetic satisfaction. Additional trocars were inserted in 60 of 932 SILA cases (weighted proportion = 0.07, 95% CI: 0.05 to 0.10).

Conclusion:

Given the diminishing difference in operative time and manageable postoperative pain compared with CLA, SILA may be considered a viable alternative for the treatment of acute appendicitis, particularly in selected patients for whom cosmetic outcomes are a priority.

HIGHLIGHTS

• With more recent surgeries, there has been a decreasing trend in the mean difference in operative time between the single-incision laparoscopic appendectomy (SILA) and three-port conventional laparoscopic appendectomy (CLA) groups.

• Although the CLA group required fewer additional analgesics, there were no significant differences in pain scores at 12 or 24 h between the SILA and CLA groups.

Introduction

The traditional surgical approach for acute appendicitis has been open appendectomy via a transverse incision at McBurney’s point. Since the advent of laparoscopy, the three-port laparoscopic appendectomy has become the standard of care, although a recent shift toward single-incision laparoscopic appendectomy (SILA) has emerged. Compared to conventional laparoscopic appendectomy (CLA), SILA offers a cosmetic advantage by requiring only a single incision. Because this incision is typically made around the navel, the resulting scar is less visible, and a single incision may also be less painful than multiple incisions^[1,2].

However, performing surgery through a single incision restricts the movement of instruments and the camera, which can make the procedure more challenging for the surgeon. Because multiple instruments must pass through one incision − and the incision in SILA is generally longer than each of the multiple incisions used in CLA − the tissue manipulation may be greater, potentially resulting in increased postoperative pain^[3,4].

Due to these unresolved issues and concerns regarding the technical challenges for the surgeon, SILA has not been widely adopted despite its cosmetic benefits and 15 years of clinical use. Appendectomy is frequently performed as an emergency procedure and is often carried out by surgical trainees as a basic operation, which presents additional obstacles to the widespread adoption of advanced techniques^[5].

Previous meta-analyses have demonstrated the benefits of SILA in terms of shorter hospital stays and earlier return to work^[6–13]. However, these studies have not established that SILA offers comparable operative time to CLA. With the widespread adoption of laparoscopic techniques and advancements in surgical instruments, single-incision laparoscopic surgery (SILS) is becoming increasingly prevalent across various surgical fields^[14,15]. Accordingly, we aimed to evaluate changes in operative time for SILA as surgeons gain experience with single-port surgery and overcome ergonomic challenges. Furthermore, controversy persists regarding postoperative pain, with discrepancies among recent meta-analyses and unexplained heterogeneity in the data^[10–13].

Therefore, we conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing SILA and CLA for the treatment of acute appendicitis, focusing on operative time and postoperative pain, which remain matters of debate.

Methods

This work has been reported in line with AMSTAR (Assessing the methodological quality of systematic reviews) and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) Guidelines^[16,17]. This study also complies with the TITAN (transparency in the reporting of artificial intelligence) guidelines 2025^[18].

An electronic search was performed using PubMed, Embase, and the Cochrane Central Register of Controlled Trials up to January 2025. The search strategy combined the following terms: “appendectomy” or “appendicectomy,” “single*” or “umbilical*,” and “three*,” “multi*,” or “conventional” (Supplementary Digital Content Table 1, available at: http://links.lww.com/JS9/F169).

SILA was defined as a laparoscopic appendectomy performed through a single incision, regardless of the type of surgical device or the number of ports used. CLA was defined as a laparoscopic appendectomy utilizing three ports. Only RCTs comparing SILA and CLA were included. We included only patients with acute appendicitis and excluded studies involving interval appendectomy.

The primary outcomes were operative time and postoperative pain, which were assessed using either a visual analogue scale (VAS) or a numeric rating scale (NRS), along with analgesic requirements. Secondary outcomes included the incidence of postoperative complications, additional trocar requirements, open conversion rates, and cosmetic satisfaction. Subgroup analyses for operative time and complications were prespecified for studies involving pediatric patients, patients with uncomplicated appendicitis, and studies in which experienced surgeons (beyond the learning curve for SILA or SILS) participated.

Two reviewers (K.-G.L. and A.H.) independently screened titles, abstracts, and full texts for study selection, data extraction, and quality assessment. Any disagreements were resolved through discussion or by consulting a third evaluator (S.H.).

The risk of bias was assessed based on random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, completeness of outcome data, selective reporting, and other biases (including baseline imbalances, early stopping, vested interest bias, and expertise bias). Risk of bias concerning the blinding of outcome assessment and incomplete outcome data was evaluated separately for each primary outcome (operative time and postoperative pain).

Data extraction

For dichotomous outcomes, the number of events was extracted. For continuous outcomes, the mean and standard deviation (SD) were recorded. When SDs were not reported, they were estimated using available statistics (e.g., P-values) according to the Cochrane Handbook^[19]. In cases where a P-value was unavailable, we computed the mean-to-SD ratio for each study and used the average ratio to impute the missing SD based on Buck’s regression^[20]. For operative time, the study initiation year was also extracted to enable meta-regression analysis assessing changes in mean difference (MD) over time. For postoperative complications, the number of events was extracted. For postoperative pain, we recorded the mean and SD of pain scores at 12 and 24 h postoperatively, as well as analgesic doses. In studies where pain levels were presented only graphically, we used a ruler function in our editing program to estimate the values. Data on additional trocar insertion were extracted solely for the SILA group, while open conversion data were extracted from both groups.

Statistical analysis

Statistical analyses were conducted using R (Version 4.3.1; R Foundation for Statistical Computing, Vienna, Austria). Continuous outcomes were expressed as weighted MDs with 95% confidence intervals (CIs) using a random-effects model. Dichotomous outcomes were expressed as risk ratios (RRs) with 95% CIs. Meta-regression for operative time was performed based on the study initiation year. The need for additional trocar insertion was expressed as a proportion and combined using a generic inverse variance method. For cosmetic satisfaction and analgesic requirements, which were reported in different units across studies, standardized mean differences (SMDs) were used. Heterogeneity was assessed using the chi-square test, with a P-value <0.1 indicating significant heterogeneity. Sensitivity analyses were performed for operative time and postoperative pain to assess the robustness of the synthesized results. Funnel plots based on the MD in operative time and the RR for postoperative complications were constructed to evaluate potential publication bias.

Results

Characteristics of the included studies

A total of 1764 studies were identified through the search process (Fig. 1). After merging duplicates, 1190 studies remained. Abstract screening reduced the number to 121 studies, and full-text evaluation was performed on 121 studies for eligibility. Studies were excluded for the following reasons: 58 observational studies, letters, and editorials; 32 unpublished conference presentations; two studies involving modified surgical procedures that did not meet the SILA definition; one study performed under spinal anesthesia; and one study that did not provide data for continuous variables. Additionally, one duplicate publication and one subsequent analysis of a main study were excluded. Ultimately, 25 studies^{[1–4,21–41]} were included in the meta-analysis. For the main analyses, 21 studies^{[1–4,25–41]} with a total of 2454 patients (1217 undergoing SILA and 1237 undergoing CLA) were analyzed, with 4 studies^[21–24] excluded due to a high risk of bias in the randomization process.

Figure 1.

PRISMA flow diagram.

Studies were published beginning in 2010, with study initiation dates as early as 2008 (Table 1). Six studies^{[25,29,35,38–40]} included only pediatric patients, while 6 studies^{[1,4,21,23,24,27]} included only adult patients, and 13 studies^{[2,3,22,26,28,30–34,36,37,41]} included patients of all ages. There were nine studies^{[4,22,27,29,30,32,37,39,41]} in which experienced surgeons beyond the learning curve for SILA or SILS participated. Fourteen studies^{[3,4,21,23,25,26,30–32,35–37,39,40]} excluded complicated appendicitis.

Table 1.

Demographic characteristics of the included studies

	Publication year	Study initiation year	Country	Mean age (±SD)	Operator (number/level/beyond learning curve)	Sample size	Inclusion criteria: disease severity
Vidal et al [21]	2010	2008	Spain	33 ± 2.5	2/staff/–	30	Uncomplicated
Park et al [3]	2010	2009	Korea	26.1	1/staff/–	40	Uncomplicated
St. Peter et al [25]	2011	2009	USA	11.1 ± 3.4	Multi/staff/–	360	Uncomplicated
Park et al [26]	2012	2008	Korea	27.5 ± 12.1	2/staff/–	104	Uncomplicated
Vilallonga et al [22]	2012	2009	Spain	35.8 ± 13.3	3/staff/yes	95	All
Teoh et al [27]	2012	2009	Hongkong	39.9 ± 15.6	Multi/staff/yes	200	All
Kye et al [28]	2013	2009	Korea	28.4 ± 13.2	1/staff/–	102	All
Perez et al [29]	2013	2009	USA	8.8 ± 0.6	1/staff/yes	50	All
Frutos et al [30]	2013	2009	Spain	29.6 ± 11.7	Multi/staff/ yes	184	Uncomplicated
Pan et al [31]	2013	2009	China	34.5 ± 14.7	2/staff/–	84	Uncomplicated
Lee et al [32]	2013	2010	Korea	28.4 ± 16.3	Multi/staff/ yes	248	Uncomplicated
Sozutek et al [1]	2013	2010	Turkey	30.3 ± 11.7	2/staff/–	50	All
JT Carter et al [4]	2014	2010	USA	34.5 ± 11.5	1/staff/yes	75	Uncomplicated
Malik et al [33]	2014	2011	Scotland	29.5	Multi/staff or resident/–	77	All
Villaobos et al [34]	2014	2011	Spain	29.1 ± 9.25	3/–/–	120	All
Wu et al [35]	2014	2011	China	8.5 ± 2.1	Multi/staff or resident/–	60	Uncomplicated
Singh et al [36]	2017	2014	India	27.5	–	29	Uncomplicated
Alexander et al [23]	2017	2014	India	NA	NA	100	Uncomplicated
Kang et al [37]	2018	2009	Korea	31 ± 15.1	Multi/staff/yes	180	Uncomplicated
Binet et al [38]	2018	2017	France	11.1 ± 2.4	1/staff/–	80	All
Duza et al [2]	2019	2013	Argentina	32.9 ± 11.6	Multi/–/–	147	All
Razzaq et al [24]	2019	2018	Pakistan	39.1 ± 11.5	–	170	All
Golebiewski et al [39]	2019	NA	Poland	11.5 ± 3.5	Multi/staff/yes	50	Uncomplicated
Vejdan et al [40]	2021	2017	Iran	11.9 ± 2.5	–	140	Uncomplicated
Kim et al [41]	2023	2014	Korea	41.7 ± 14.3	Multi/–/yes	98	All

Surgical techniques and device configurations varied across the studies. A detailed summary of incision lengths, access devices, and drain placement in SILA, and of port configurations employed in CLA, is provided in Supplementary Digital Content Table 2, available at: http://links.lww.com/JS9/F170. While not all studies reported this information consistently, several studies specified the use of glove ports, SILS port systems, or combinations of 2-, 5-, and 10–12-mm ports for SILA with an incision length of 1–3 cm, and various combinations of 5- and 10–12-mm ports for CLA.

Risk of bias assessment

Regarding randomization and allocation, three studies^[21–23] adopted the alternating allocation method, resulting in a high risk of selection bias, and one study^[24] did not describe the randomization process (Fig. 2). Additionally, there was no description of the randomization process in nine studies^{[1,3,21–24,26,31,32,40]}. Blinding of surgeons, patients, or outcome assessors for operative time is inherently unfeasible in surgical RCTs. Regarding the blinding of postoperative pain assessment, five studies^{[25,27,29,36,38]} used separate outcome assessors or similar dressings for patients.

Figure 2.

(A) Risk of bias summary, (B) Risk of bias graph.

In terms of outcome data completeness, the dropout rate was less than 10% in all studies. However, in the study by Villalonga et al^[22], which used alternating allocation, only 46 patients in the SILA group and 41 in the CLA group were analyzed out of 92 allocated, leading to a high risk of attrition bias.

Seven trials^{[4,25,27,30,32,37,40]} had their protocols published in trial registries. Concerning other biases, three studies^[2,26,30] exhibited baseline imbalances, and two studies^[22,36] performed per-protocol analyses. In one study, a consultant surgeon participated more frequently in the SILA group than in the CLA group (21% vs 8%)^[33]. Additionally, an identical paper was published in two separate journals^[24].

We excluded four studies^[21–24] from the main analyses because they could not be considered true randomized trials despite being labeled as such. These studies either employed an alternating quasirandomization method or failed to describe the randomization process, making it impossible to confirm that they were genuinely randomized.

Primary outcomes

Operation time

Operation time was reported in all 21 included RCTs^{[1–4,25–29,40,41]} (Fig. 3). The meta-analysis indicated that operative time for SILA was, on average, 3.80 min longer than that for CLA (MD = 3.80 min, 95% CI: −0.25 to 7.85; P = 0.07). There was significant heterogeneity (I² = 90%, P < 0.01). Subgroup analyses based on study characteristics also showed significant heterogeneity, with I² values exceeding 85% in all cases.

Figure 3.

Forest plot comparing the mean operation time for SILA vs CLA in (A) all studies, (B) studies for pediatric patients, (C) studies with experienced surgeons, (D) studies with uncomplicated appendicitis.

In six studies^{[1,4,21,23,24,27]} for pediatric patients, there was no significant difference in mean operative time between the two groups (MD = 2.20 min, 95% CI: −7.79 to 12.19, P = 0.67). However, in eight studies^{[4,27,29,30,32,37,39,41]} involving experienced surgeons, the meta-analysis showed that SILA had a significantly longer operative time than CLA (MD = 7.71 min, 95% CI: 2.19 to 13.24; P < 0.01). Similarly, in 12 studies^{[3,4,25,26,30–32,35–37,39,40]} that excluded complicated appendicitis, the operative time for SILA was significantly longer than that for CLA (MD = 6.98 min, 95% CI: 1.45 to 12.51; P = 0.01).

Meta-regression of 20 studies^{[1–4,25–38,40,41]} (excluding 1 study^[39] with an unavailable initiation year) arranged chronologically by study initiation year revealed a significant trend toward a decrease in the MD in operative time with more recent operations (P = 0.003) (Fig. 4). Among studies focusing on uncomplicated appendicitis, 11 studies^{[3,4,25,26,30–32,35–37,40]} showed that 66.7% (8/12) were initiated between 2008 and 2010, compared with 37.5% (3/8) from 2011 to 2017.

Figure 4.

Bubble graph of meta-regression for mean differences in the operation time (SILA-CLA) according to study initiation year (Studies with uncomplicated appendicitis are shown as red bubbles).

Postoperative pain

Three studies^[1,3,32] reported pain scores at 12 and 24 h postoperatively along with additional analgesic requirements. A meta-analysis of eight studies^{[1–4,30,32,36,41]} reporting pain scores at 12 h using the VAS showed no significant difference between groups (MD = −0.04, 95% CI: −0.72 to 0.63, P = 0.91), although significant heterogeneity was present (I² = 82%, P < 0.01) (Fig. 5). Similarly, in eight studies reporting pain scores at 24 h using either the VAS^{[1,3,27,28,32,36,41]} or the NRS^[33], no significant difference was observed (MD = 0.08, 95% CI: −0.30 to 0.46, P = 0.67), with moderate heterogeneity (I² = 57%, P = 0.02). Seven studies^{[1,3,25,27,28,32,37]} reported the total dose of analgesics, while six studies^{[1,3,27,28,32,37]} specifically reported the dose of additional analgesics. The meta-analysis of these six studies indicated that the CLA group required significantly fewer additional analgesics (SMD = 0.24, 95% CI: 0.10 to 0.38, P < 0.01), with low heterogeneity (I² = 28%, P = 0.23). In one study by Peter et al^[25], patients in the SILA group received more total analgesics than those in the CLA group (mean ± SD: 9.6 ± 4.9 vs 8.5 ± 4.3, P = 0.04).

Figure 5.

Forest plot comparing postoperative pain scores and additional analgesic requirements following SILA vs CLA. (A) Pain score at postoperative 12 h, (B) Pain score at postoperative 24 h, (C) Additional analgesic requirements.

Secondary outcomes

Postoperative complication

The incidence of postoperative complications was reported in all 21 studies^{[1–4,25–41]}. The overall incidence was 7.7% (94/1217) in the SILA group and 7.4% (91/1237) in the CLA group. The meta-analysis showed no significant difference between the groups (RR = 1.07, 95% CI: 0.81 to 1.41, P = 0.54) (Fig. 6), with no heterogeneity (I² = 0%, P = 0.99). In a subgroup of nine studies^{[1,2,27–29,33,34,38,41]} that included both uncomplicated and complicated appendicitis, the incidence was 9.7% (44/460) in SILA and 8.7% (40/459) in CLA, with no significant difference (RR = 1.10, 95% CI: 0.73 to 1.65, P = 0.47). Among the 16 studies that reported reoperation or specified treatment according to complication type, the reoperation rate was 1 out of 914 cases (0.1%) in the SILA group and 5 out of 928 cases (0.5%) in the CLA group (P = 0.19).

Figure 6.

Forest plot comparing the incidence of postoperative complications following SILA vs CLA in (A) all studies and (B) studies including complicated appendicitis.

Additional port insertion and open conversion

Seventeen studies^{[1,3,4,25,28–39,41]} reported cases of additional port insertion, which occurred in 60 out of 932 SILA cases (weighted proportion = 0.07, 95% CI: 0.05 to 0.10) (Fig. 7), with low heterogeneity (I² = 31%, P = 0.11). In a subgroup of seven studies^{[1,26,27,33,34,38,41]} that included both uncomplicated and complicated appendicitis, additional ports were inserted in 13 out of 287 cases (weighted proportion = 0.05, 95% CI: 0.02 to 0.12), though with significant heterogeneity (I² = 52%, P = 0.05). Open conversion was reported in 18 studies^{[1–4,25,27–35,37–39,41]}, with an incidence of 0.3% (3/1091) in the SILA group and 0.4% (4/1090) in the CLA group. No cases of open conversion were reported in studies involving pediatric patients or those with uncomplicated appendicitis. In one study by Teoh et al^[27], where conversion was defined as either additional port insertion or open conversion, the conversion rate was 8.2% (8/98) in the SILA group compared with 3.1% (3/97) in the CLA group (P = 0.26).

Figure 7.

Forest plot of additional port insertion following SILA in (A) all studies and (B) studies including complicated appendicitis.

Cosmesis satisfaction

Cosmetic satisfaction scores were reported in 10 studies^{[2–4,27,31–33,36,37,41]}. The meta-analysis indicated that cosmetic satisfaction was significantly higher in the SILA group (SMD = −0.68, 95% CI: −1.03 to −0.33, P < 0.01) (Fig. 8), although significant heterogeneity was present (I² = 89%, P < 0.01).

Figure 8.

Forest plot comparing cosmesis satisfaction scores following SILA vs CLA.

Sensitivity analysis

When the initially excluded four studies^[21–24] were added, the meta-analysis for operative time showed that the MD increased slightly from 3.80 to 4.02 min, reaching statistical significance (MD = 4.02 min, 95% CI: 0.69 to 7.36; P = 0.02) (Supplementary Digital Content Fig. 1, available at: http://links.lww.com/JS9/F171), with significant heterogeneity (I² = 90%, P < 0.01). Meta-regression, including five studies^[21–24,39], still yielded a significant P-value (P = 0.021) (Supplementary Digital Content Fig. 2, available at: http://links.lww.com/JS9/F172).

For postoperative pain, two studies^[22,23] were added to the 12-h pain score analysis and two studies^[21,23] to the 24-h analysis, with no additional studies for additional analgesic requirements (Supplementary Digital Content Fig. 3A, available at: http://links.lww.com/JS9/F173, Supplementary Digital Content Fig. 3B, available at: http://links.lww.com/JS9/F174). The MD for the 12-h pain score changed from −0.04 to −0.13 (MD = −0.13, 95% CI: −0.62 to 0.36, P = 0.67) with significant heterogeneity (I² = 81%, P < 0.01). At 24 h, the MD adjusted from 0.08 to 0.06 (MD = 0.06, 95% CI: −0.30 to 0.42, P = 0.74), with significant heterogeneity (I² = 51%, P = 0.03).

Funnel plot exploration

Visual inspection of the funnel plot for operative time showed a small indication of a trend but no clear asymmetry, but this is more likely to be explained by the substantial heterogeneity between the included studies (I² = 95%, P < 0.01) than by publication (Fig. 9A). Furthermore, the apparent asymmetry was not statistically significant by Egger’s test (P = 0.268). The funnel plot for the incidence of postoperative complications, which showed no heterogeneity (I² = 0%, P = 0.94), also showed no evidence of asymmetry (Egger’s test, P = 0.504) (Fig. 9B).

Figure 9.

Funnel plot of (A) operation time and (B) the incidence of postoperative complications.

Discussion

Poor randomization procedures in RCTs can introduce selection bias, thereby undermining one of the key strengths of randomized studies. Therefore, we excluded four studies^[21–24] from our analysis due to concerns regarding the randomization process. RCTs evaluating new surgical techniques are inherently susceptible to bias because blinding the operator is not feasible, which may affect intraoperative outcomes. As a result, all studies in this review were considered at high risk of bias regarding the blinding of operators, patients, and outcome assessors for operative time. Lack of blinding among investigators and participants can also influence postoperative outcomes; only five studies^{[25,27,29,36,38]} ensured that caregivers were blinded or used identical dressings.

Operative time, as an indicator of the feasibility of a new technique, is influenced by numerous factors. For example, in pediatric RCTs, the Vejdan trial^[40] − employing an extracorporeal approach for SILA − demonstrated a significant reduction in operative time compared with CLA. Moreover, a meta-analysis of extracorporeal SILA in pediatric patients suggested shorter operative times compared to conventional intracorporeal SILS or CLA^[42]. Differences in surgeons’ skills can also affect operative time. In two RCTs that assessed surgeon-perceived difficulty, SILA was associated with significantly higher difficulty scores compared to CLA. For instance, St. Peter et al reported higher Likert scale ratings for SILA^[25], and Malik et al found a greater proportion of SILA cases rated as “extremely difficult”^[33]. However, in a study by Perez et al, the timing of operations within the study cohort was compared, showing that the operative time gap between SILA and CLA narrowed between the early and late cohorts^[29]. This indicates that technical difficulty may improve with experience and familiarity. Given that each study involved surgeons with varying experience levels and different team compositions, we performed an analysis focusing on experienced surgeons; however, this did not reduce the observed differences. The overall operative time is influenced by the entire surgical team − including the scopist and scrub nurse − not solely by the primary operator^[43].

The meta-regression showed that as SILA is increasingly implemented and surgical teams gain experience, the operative time difference decreases. Initially, one might expect that in cases of uncomplicated appendicitis − where intra-abdominal handling is less challenging − the operative time difference between SILA and CLA would be reduced^[28,38]. However, our findings indicate the opposite: studies on uncomplicated appendicitis were predominantly conducted in earlier years, while later studies included more complicated cases. This suggests that advancements in laparoscopic technology and increased team familiarity with SILA are critical factors in improving its feasibility. Beyond appendectomy, we believe that the findings of this study suggest the growing feasibility of single-port techniques in other surgical procedures.

Regarding postoperative pain, previous meta-analyses have suffered from inconsistent baseline time points or limited pooled analyses^[10–13]. In our meta-analysis, only one study^[33] used the NRS for postoperative pain at 24 h, while the others^{[1,3,27,28,32,35,41]} used the VAS at 12 and 24 h. Both scales evaluate pain intensity on a 0–10 scale and are considered interchangeable in clinical settings. A sensitivity analysis excluding the NRS-based study yielded results consistent with the overall findings. Therefore, inclusion of the NRS-based study was considered appropriate. For studies that presented data graphically, we extracted numerical values using digital estimation methods. Because methods, dosages, and types of analgesics varied, we used standardized MDs to compare analgesic requirements. Although patients in the SILA group required more analgesics during hospitalization, the similar VAS scores at 12 and 24 h indicate that this difference can be effectively managed.

In terms of complications, both existing studies and our meta-analysis consistently demonstrate no significant differences between SILA and CLA, including in analyses that encompassed complicated appendicitis, supporting the overall safety of SILA. Umbilical hernia, a late complication, was reported in six studies, with 3/326 (0.9%) in the SILA group and 0/324 in the CLA group. Meta-analyses of SILS have reported that the incisional hernia rate was higher in SILS than that in the conventional method^[14,44,45]. Most trials in our review had short-term follow-up (<1 year), leaving long-term follow-up or outcomes uncertain.

Additional port insertion was only analyzed in the SILA group because it is rarely done in CLA, and the pooled proportion was 0.07 in the SILA group, indicating that an additional port was required in approximately 1 out of every 14 cases. Notably, including complicated cases did not increase the frequency of additional port use; however, extensive peritoneal adhesions from a retrocecal appendix may necessitate an extra port^[46]. Regarding drain insertion, some reported successful placement of the drain through the umbilical incision in our study^[27,28]. Others used a 5 mm additional trocar in the suprapubic or right lower quadrant area^[3,21,34]. These findings suggest that while an additional port may occasionally be required for drain placement, many cases can be managed without creating a separate incision.

Cosmetic satisfaction was evaluated using a different questionnaire in each study, with different timing. However, the reference was to normal skin. The studies found that SILA was superior to CLA, confirming our expectations for the cosmetic effect of a single incision. SILA typically requires a 1–3 cm umbilical incision, and a recent RCT reported a shorter total incision length in SILA (mean 2.0 cm) than in CLA (mean 2.7 cm)^[41]. Although SILA may require a longer umbilical incision, it avoids the three separate scars created by CLA, and the umbilicus provides a natural fold and concealment, potentially contributing to improved cosmetic satisfaction following healing.

Our study provided novel insights that have not been previously reported in the existing literature. These insights offer further clarification on two key outcomes that have been the subject of persistent debates in previous studies, including recent meta-analyses^[6–13]: operation time and postoperative pain. The primary focus of our analysis was an in-depth exploration of the temporal trend, with the objective being to accurately capture the evolution of surgical proficiency. In particular, the time point at which each surgery was performed was identified, rather than simply the year of publication, for consideration of gaps between the dates of publication and surgery. Meta-regression analyses based on this data suggest that the difference in surgical time between SILA and CLA has significantly decreased over time. In order to address the issue of postoperative pain, a calibrated approach was adopted for the extraction of data from graphical formats in individual papers, enabling us to include more comprehensive information than was possible in previous meta-analyses. Using metrics that accounted for differences in measurement scales across studies, we ascertained that SILA was associated with greater analgesic use, but there was no significant disparity in pain scores, thereby indicating that postoperative pain can be effectively managed.

However, this study has several limitations. First, surgical expertise varied across trials; in one trial, different surgeons performed procedures in the two groups^[33], likely contributing to heterogeneity in operative time. Nevertheless, given that appendectomy is a fundamental procedure and that differences in operative time have diminished in recent years − with no heterogeneity in postoperative complications − this limitation may be acceptable. Although the difference in operative time between SILA and CLA was statistically significant (MD of 3.8 min), it can be of limited clinical significance.

Second, substantial heterogeneity was observed in postoperative pain at 12 h (I² = 82%) and 24 h (I² = 57%), as well as in cosmesis satisfaction (I² = 89%). To further explore the sources of this heterogeneity, we conducted subgroup and sensitivity analyses. Meta-regression based on the year of surgery and subgroup analyses stratified by surgeon experience (i.e., beyond the learning curve for SILS or SILA) and disease severity did not reveal any statistically significant patterns. No analyzable data were available from studies involving exclusively pediatric populations.

In a sensitivity analysis excluding the outlier study (Park 2010^[3]), the variation range for postoperative pain narrowed (from −1.4 to 2.3 →−1.4 to 0.9), but heterogeneity remained substantial (I² = 82% → 79% for 12-h pain; I² = 57% → 48% for 24-h pain) (Supplementary Digital Content Fig. 4A, available at: http://links.lww.com/JS9/F175, Supplementary Digital Content Fig. 4B, available at: http://links.lww.com/JS9/F176, Supplementary Digital Content Fig. 4C, available at: http://links.lww.com/JS9/F177). The persistent heterogeneity in postoperative pain and cosmesis satisfaction is likely attributable to the inherently subjective nature of these outcomes.

The variability in the timing of pain assessment (e.g., 6, 12, 24, or 48 h postoperatively) may also have contributed to the observed heterogeneity. Although our analysis focused on the most commonly reported time points (12 and 24 h), inconsistent pain evaluation schedules across studies may have introduced additional between-study variance. Unfortunately, limited data availability precluded subgroup analyses by assessment time. This limitation should be taken into account when interpreting pain-related outcomes.

Randomization and blinding in emergency surgical trials pose inherent challenges, particularly when the procedure under investigation, such as SILA, is not yet a standard approach. This limitation applies broadly to surgical RCTs, where blinding of the surgeon is generally infeasible due to the nature of the intervention (e.g., number and placement of ports). Therefore, interpretation of subjective outcomes such as postoperative pain and cosmetic satisfaction should be approached with caution.

Third, the lack of long-term follow-up in most studies precluded definitive conclusions regarding outcomes such as incisional hernia and long-term cosmetic satisfaction. Future investigations should require prospective studies with extended follow-up, ideally alongside economic evaluations modeling to assess cost-effectiveness, before broader generalization of SILS, including SILA, can be recommended.

Although the open conversion rate was comparable between SILA and CLA, the slightly longer operative time and the use of additional ports in the SILA group may reflect intraoperative challenges undertaken to ensure safety. However, in studies that included complicated appendicitis, the comparable outcomes between the two groups suggest that the safety of SILA was not compromised when performed by experienced surgeons.

While few randomized trials have been conducted in recent years, observational studies on SILA continue to emerge, indicating its ongoing clinical relevance in certain cases^[5,47–49]. Furthermore, with the recent advent of robotic single-port platforms, SILA may serve as a cost-effective alternative in appropriate settings^[50].

In conclusion, our study demonstrated that SILA offers superior cosmetic satisfaction compared with CLA, with no differences in postoperative complications. Although the SILA group required higher analgesic use, pain scores at 12 and 24 h postoperatively were similar between groups. As surgical techniques continue to improve, the operative time difference diminishes, suggesting that ergonomic challenges are being overcome. However, due to the substantial heterogeneity across studies and the need for advanced surgical skills, SILA should be reserved for experienced surgeons and may be most appropriate in pediatric or younger female patients with uncomplicated appendicitis for whom cosmetic outcomes are a priority. Accordingly, SILA can be considered a viable alternative to CLA in carefully selected cases.

Supplementary Material

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Ethical approval

This is systematic review and meta-analysis which do not need the ethical approval.

Consent

Not appilcable.

Sources of funding

This research was supported by a grant from the National Research Foundation of Korea (Grant No.: 2022R1A2C101043711). The funder had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.

Author contributions

Study concepts: S. H. Study design: S. H., K.-G. L. Data acquisition: K.-G. L., A. H. Quality control of data and algorithms: S. H., K.-G. L., A. H. Data analysis and interpretation: S. H., K.-G. L., A. H. Statistical analysis: S. H., K.-G. L. Manuscript preparation: S. H., K.-G. L. Manuscript editing: S. H., K.-G. L., A. H., M. K. K., J. S. P. Manuscript review: S. H., K.-G. L., A. H., M. K. K., J. S. P.

Conflicts of interest disclosure

The authors declare that they have no conflicts of interest.

Guarantor

Seokyung Hahn.

Research registration unique identifying number (UIN)

This is systematic review and meta-analysis which do not needs the ethical approval. The study protocol is publicly available on PROSPERO (CRD420250454205). https://www.crd.york.ac.uk/ PROSPERO/#recordDetails.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability statement

The study is a systematic review and meta-analysis and the data is extracted from public database.