Introduction

The surgical technological innovation in different surgical fields, including gynecology, allowed to improve the surgical outcomes [1, 2], reducing the complication rate and the aesthetic impact [3,4,5,6,7,8,9]. Several ultra-minimally invasive technologies are suitable to reduce the invasiveness of standard laparoscopic surgery [10,11,12,13,14,15,16,17]. Compared to the different techniques available, single-site surgery acquired relevance in the gynecologic surgical field, since the access to the abdominal cavity was obtained through a single 20–30 mm transumbilical port. However, some limitations have been reported, such as the absence of triangulation, the reduction of surgical dexterity, and consequently, a prolonged surgical time [18, 19]. The ultra-minimally invasive surgery has been directed towards a more sophisticated technology designed to reduce the number and extent of skin incisions required. New surgical robotic platforms are available with the aim of overcoming the limits of laparoscopy [20,21,22,23,24,25,26]. The single-site robotic platform allows the surgeon to achieve remarkable ergonomic comfort, overcoming flexible or clashing instruments, as in the case of single-site laparoscopy. In this context, the single-site robotic platform acquired importance in the field of ultra-minimally invasive surgery.

Since Fader performed the first robotic single-site hysterectomy, the research has focused on using robotic single-site surgery (RSSS) for all gynecological conditions, both malignant and benign [27], showing better practicality in intracorporeal sutures with an acceptable learning curve due to the characteristics of the surgical arms compared to the classic laparoscopy [28].

Several studies in the literature have demonstrated the excellent surgical success and aesthetic outcome related to RSSS with similar complication rates compared to traditional surgery [29]. A recent analysis considers RSSS more cost-effective than robotic multi-site surgery [30]. Furthermore, RSSS is also associated with a lower hospital stay, less post-operative pain, and better patient satisfaction compared to multi-site techniques [31]. All these benefits allowed this new technology to spread rapidly in different surgeries [32].

This review aims to examine the studies available in the literature on RSSS in gynecology both for benign and malignant indications in terms of operative outcomes.

Methods

In June 2019, a systematic review of the literature was done on Pubmed, Scopus, and Google Scholar search engines.

We searched for the following keywords: “robotic single-site surgery and Gynecology”, “robotic single port surgery and Gynecology”, “robotic single-incision surgery and Gynecology”, “robotic laparoendoscopic single-site surgery and Gynecology”.

The systematic review was carried out in agreement with the preferred reporting items for systematic reviews and meta-analyzes statement (PRISMA) [33]. Two independent authors (CVA and AG) double-checked the research to exclude repeated articles. Articles with non-English language, case reports, reviews, case series with less than 10 cases were excluded. All relevant studies cited by the selected papers were also included in the analysis. Of all the studies we reported the type of surgery, surgical indication, operative time, complications, cases with conversion to other surgery types, EBL, BMI, and type of robot used (Table 1).

Table 1 Characteristics of included studies
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We divided the studies into 3 groups, according to the type of condition included: group 1 including only cases with benign pathology, group 2 studies with only malignant disease patients, and group 3 including both. Any surgical modification to the RSSS, from the placement of an additional trocar to the open surgery, was considered as a surgical conversion.

For the complication rate, we considered the common terminology criteria for adverse events (CTCAE) grade ≥ 3 [34]. All parameters are expressed in median and percentage.

Statistical analysis

Data were displayed as standard deviation (SD) or as number (percentage). Categorical variables were compared using the Chi-square or Fisher exact test. Between-group comparison of continuous variables was undertaken using the t test and the Mann–Whitney nonparametric equivalent test. Two-sided p-values were calculated, and p values < 0.05 were considered as statistically significant. Comparisons between > 2 groups were performed using the Kruskal–Wallis test or ANOVA when appropriate. Meta-analyses of proportions were used to combine data. Between-study heterogeneity was explored using the I2 statistic, which indicates the percentage of between-study variation that is due to heterogeneity rather than chance. A value of I2 of 0% indicates no observed heterogeneity, whereas values ≥ 50% indicate a substantial level of heterogeneity. Given the small sample size of the included studies, a random effect model was preferred, regardless of I2. StatsDirect 3.0.17 (StatsDirect Ltd, Altrincham) statistical software was used for all data analyses.

Results

Two hundred and fifty total studies were obtained by searching for keywords; 103 with ‘robotic single-site surgery and Gynecology’, 61 with ‘robotic single PORT surgery and Gynecology’, 47 with robotic single-incision surgery and Gynecology, and 39 with ‘robotic laparoendoscopic single-site surgery and Gynecology’ respectively. With the removal of the duplicate articles and screening all the articles with the selection criteria, 27 articles were included in the review [22, 30, 35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59]. PRISMA flow chart is shown in Fig. 1.

Fig. 1
figure 1

Flow-chart of the included studies

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Fourteen studies were included in (group 1) [30, 35, 38, 42, 44,45,46,47,48,49,50,51, 53, 56], eight (in group 2) [22, 39,40,41, 52, 54, 57, 58], and five articles (in group 3) [36, 37, 43, 55, 59], with 605, 260, and 200 cases respectively. The results are reported in Table 2. The median BMI was 27, 25.7, and 26 in groups 1, 2, and 3, respectively. The median of the operative times was 144.3 min for studies including only benign pathologies, 131 min for those including only malignant pathologies, and 134 min for those including both. The median estimated blood loss (EBL) was 57.9 ml, 75 ml, and 50 ml in groups 1, 2, and 3, respectively. Two (0.3%) patients in the group 1, 3 (1.2%) patients in group 2 of malignancies, and 5 (2.5%) in group 3 were converted. Five cases of multiport robotic surgery, two classic laparoscopy, two necessary additional port cases, and one vaginal surgery as conversion types have been reported in the three groups.

Table 2 The studies were grouped according to the patients’ pathology
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The median length of stay was 1.8 days for group 1, 2.2 days for group 2, and 1.0 day for group 3, respectively. Ten (1.7%) patients in the benign pathology group, 16 (6.2%) patients with malignant disease, 5 (2.5%) patients with both benign and malignant disease developed major complications. As shown in Table 1, eight vascular, eight intestinal, five vaginal, four infectious, three urinary, one thrombotic, one nervous, one lymphatic complication has been reported in the three groups.

No significant differences were found between groups for BMI (p = 0.235), operative time (p = 0.723), EBL (p = 0.342), and hospital stay (p = 0.146). The complications and conversions incidence through pooled analysis showed a higher general conversion rate (p = 0.012) in group 3 (3.0%) and higher complications rate (p = 0.001) in group 2 (5.3%) compared to the other groups (Fig. 2).

Fig. 2
figure 2

Pooled proportion of conversion and complications among the three groups

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In all the studies selected, the Da Vinci Si® surgical system (Intuitive Surgical, Sunnyvale, CA, USA) was used.

Discussion

The single-site robotic platform represents today an impressive and evolving technology. The field of ultra-minimally invasive surgery aimed to reduce the surgical and aesthetic impact, maintaining the same procedural complexity. The reduction of invasiveness is one of the main factors to improve the quality of life of patients, [60,61,62,63,64,65].

In the study by Chung et al., two critical steps during surgery are reported: lymphadenectomy in patients with malignant disease and, more generally, the vaginal cuff closure [39]. According to the same authors, lymphadenectomy requires a long learning curve, while the difficulty of the vaginal cuff closure could be overcome by replacing the classic curved needle with a straight one [39].

The main advantage of this technique performed by robotics is to overcome the ergonomic limitations and the absence of a triangulation of single-site laparoscopy [32]. Furthermore, the amplification of precise movement and availability of three-dimensional vision should also be considered as factors improving the surgical performance and outcomes. Robotic surgery also allows the so-called ‘chopstick effect’ of single-site laparoscopic surgery to be overcome. In particular, the nearness of the laparoscopic instruments, causes a mechanical conflict between the surgeons’ hands, making the surgery less ergonomic. The robotic arms, thanks to their articulation, allow us to avoid this limitation. Furthermore, the robotic system allows the instruments to cross inside the abdominal cavity, rather than crossing surgeons’ hands As reported in a recent meta-analysis, the presence of last technological innovation as the EndoWrists, allowed to perform a more precise procedure, improving especially the knotting times [32].

The angle of the surgical arms is a particularly important aspect, even in case of small precision surgery. As reported by Moon et al., the angulation of the instruments through the Da Vinci platform allows putting the instruments in a plane tangent to the surgical object, allowing an optimal approach [51].

Despite its advantages, RSSS remains a complex surgery requiring a long learning curve.

Our study shows that patients with malignant disease had a higher complication rate than patients with benign disease 5.3% vs. 1.9%, respectively.

In the case of malignant disease, complex procedures are described, such as lymphadenectomy or radical hysterectomy, with a higher burden of complications than benign surgery. As a consequence, we have observed a longer average hospital stay in group 2, even if not statistically significant.

Finally, we have found a higher conversion rate for group 3 than for the other two groups (3.0% vs. 0.7 and 1.8, respectively). In our opinion, this result is of little significance because in the studies included in the analysis there was no agreement on the definition of surgical conversion; moreover, this result could be influenced by the surgeon's expertise, not clearly homogeneous among groups.

In fact, for some authors, the conversion was considered as the addition of a single trocar, whereas for others it was defined as the transition from minimally-invasive to open surgery. The most frequently reported complications in the RSSS are the ones involving the bowel, and those related to the vaginal cuff closure. In the five bowel complications, only one required reoperation for bowel perforation, whereas the other four were simple intestinal obstructions. In the five vaginal complications, three cuff dehiscences required a reoperation, whereas two hematomas resolved by conservative treatment. The remaining complications reported in Table 1, from surgical site infection to urinary complications, were grade 2, according to the common terminology criteria for adverse events (CTCAE) [34], in line with the adverse events of classical minimally invasive gynecological surgery. In particular, the wound infection rate and the incidence of incisional hernia are probably related to a more extensive umbilical incision needed in the RSSS.

This study presents some limitations, mainly depending on the heterogeneity of the studies included, on the retrospective nature of most of the articles included, and on the limited number of cases reported in some of them. Despite this, the pooled analysis shows a low heterogeneity of the studies (I2 statistic test always < 50%).

To the best of our knowledge, this is the first analysis of the RSSS outcomes concerning the different surgical indications in the literature. In light of these considerations, technological innovations, as for benign and malignant pathologies, are aimed to improve the outcomes and the quality of life [66,67,68,69]. These considerations also apply to other non-gynecological diseases [70, 71].

Even if a comprehensive investigation of patients’ characteristics remains a fundamental part, the single-site robotic platform represents a single step toward this aspect, but some potential improvements are possible.

Conclusion

RSSS seems to be a feasible and safe technique for all gynecological surgical procedures. There are no significant differences in terms of operative time, estimated blood loss, and hospital stay when approaching to either malignant or benign conditions by RSSS. The higher complication rate for RSSS in malignant group is in line with the complications of traditional surgery for malignant conditions.