In this study, our results showed the feasibility and safety of SPLA compared to MPLA in terms of postoperative clinical outcomes. Operative times were shorter in SPLA group except skin closure time. There was no statistical difference on clinical outcomes including recovery, inflammatory laboratory, morbidity and postoperative VAS score, whereas there was lesser usage of analgesics on the day of surgery in SPLA group. In cosmetic outcomes, the SPLA group had shorter total incision length and better PSAQ results on total score, appearance and consciousness sub-items at 12 weeks postoperatively
Recently, several studies comparing with MPLA and SPLA showed different results on operation time. Some studies showed longer operation time of SPLA[12, 15–17], whereas other showed similar outcomes between two groups. [18–20] In the present study, total operation times was significantly longer in MPLA group than SPLA group (60 min vs 47.5 min). In detail, port insertion time tended to be shorter in SPLA group, because the method of using natural orifice as a port insertion site made it easy to achieve pneumo-peritoneum without additional port insertions in other quadrants. Laparoscopic procedure time was shorter in SPLA group and this result may be associated with recent development of laparoscopic instrument including surgical energy device and the accumulated experiences of surgeons. Moreover, we did not require a use of endo-bag and the specimen was extracted through the single incision site during the SPLA, which could reduce the operation time. Unlike other operation times, skin closure time was longer in SPLA group due to the need to suture the relatively long fascia line in the narrow skin incision.
In general, the degree of postoperative pain is mostly caused by trauma to muscles and parietal peritoneum.[21, 22] Since no trocar is inserted through the muscle, it is predicted to show lesser pain in patients who undergo SPLA compared to MPLA [18, 19, 23, 24]. Jatenaonkar et al. and Kye et al. showed that pain scores on day 0 and 1 were significantly less in the SPLA group than MPLA, respectively. One study reported that pain score and the number of using hydromorphone during 12 hours were lower in SPLA group compared to MPLA group . However, the other study reported significantly greater pain scores during the initial 24 hours after SPLA than after conventional approach . In that study, the authors thought that the increased pain with single-port approach was due to a longer fascia incision in the umbilicus. The number of analgesics used on the day of surgery was significantly fewer in the SPLA group, although postoperative VAS scores and the number of analgesics used on the next day of surgery weren’t significantly different in both groups. Further study is needed to evaluate the postoperative pain between two surgical approach.
Regarding postoperative complications, previous literatures reported majority of postoperative complications was surgical site infection (SSI) in laparoscopic appendectomy[23, 25, 26], although SSI rate was clearly decreased in laparoscopic approach compared to open method[27, 28] in some studies. These results can be deduced form the fact that inflamed appendix may contaminate the wound which may cause infection in open appendectomy. In studies comparing SPLA and MPLA, Peter et al. in their prospective randomized trial reported that wound infection was 3.3% in the single-incision group and 1.7% in the 3-port group, respectively, without statistically significant difference, and SG Jin et al. reported 8.7% of wound complication in single-port method compared to 5.6% of conventional method[14, 23]. A meta-analysis demonstrated that SSI rate was similar between SPLA and MPLA . In our study, there was lower SSI rate in SPLA group than MPLA group (4.2% vs. 7.8%). We think that cleansing the everted umbilicus with betadine once more after routine surgical drape is import for the prevention of surgical site infection in SPLA.
In previous studies, postoperative intra-abdominal abscess was more common in laparoscopic appendectomy than open appendectomy [30, 31]. In our study, there was no cases of intra-abdominal abscess formation after appendectomy in both single-port and three-port approach. We routinely performed meticulous irrigation and suction in pelvic cavity, paracolic gutter, and subhepatic region besides the surgical site and we used antibiotics postoperatively after discharge during 1 week for gangrenous or perforated appendicitis as needed.
Since SPLA requires a larger incision than a conventional laparoscopic incision, some researchers have wondered if SPLA can actually cause better cosmesis, because 5 mm scars are often barely noticeable after a year. Carter et al.  used their own Body Image Questionaire and Cosmetic Appearance Scale and reported that cosmetic outcomes after 6 months were excellent and indistinguishable in SPLA and MPLA groups. However, Jategaonkar et al. showed the favorable cosmetic outcomes in SPLA group using Easy-to-use scar grade that was based on patients’ subjective feeling about the postoperative scars (1 = thrilled, 2 = happy, 3 = not bothered, 4 = unhappy) . In the current study, patients who underwent SPLA checked better cosmetic outcomes in appearance and consciousness sub-items and total score, while patients’ satisfactions with their scars’ appearance and consciousness sub-items did not show the significant differences. We think that the better perception of scar image did not translate into improved satisfaction in patients with SPLA.
Our study has several limitations including its retrospective nature, small sample size, and lack of the long-term cosmetic outcomes. Moreover, PSAQ relies on the patient's subjective thoughts. A multicenter randomized prospective study to compare cosmetic outcome and pain assessment using more objective parameters between SPLA and MPLA is needed.